[0001] This application claims priority to U.S. Provisional Patent Application having Serial No. 62/074,700, which was filed November 4, 201 4. The aforementioned patent applications are hereby incorporated by reference in their entirety into the present application to the extent consistent with the present application.

Background

[0002] Hydrocarbons produced from wellheads (e.g., subsea production wellheads) often contain corrosive gases, such as carbon dioxide (CO2), hydrogen sulfide (H2S), and chloride gases, that may induce corrosion in metals utilized in various phases of producing and transporting the hydrocarbons. For example, the corrosive gases associated with the hydrocarbons may often induce uniform corrosion, sulfide stress cracking, and/or stress corrosion cracking in the metals. Accordingly, metals having increased corrosion resistance, such as martensitic stainless steel, may often be utilized in the various phases of producing and transporting the hydrocarbons.

[0003] As demand for hydrocarbons increases, efforts have focused on methods for increasing their production. These efforts may often include increasing drilling depths at the wellheads. As the drilling depths at the wellheads increase, the temperatures and pressures may also correspondingly increase. The increased temperatures and pressures, however, also increase the partial pressure of the corrosive gases, thereby increasing the corrosiveness of the gases contacting the metals.

[0004] What is needed, then, are improved metals and metal compositions and methods for treating the metals and the metal compositions.

Summary

[0005] Embodiments of the disclosure may provide a metal composition including carbon, magnesium, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, nitrogen, iron, and impurities. The metal composition may include about 0.03 wt% or less of the carbon, about 1 .00 wt% or less of the manganese, about 0.01 5 wt% or less of the sulfur, about 0.03 wt% or less of the phosphorus, about 1 .00 wt% or less of the silicon, about 3.50 wt% to about 4.50 wt% of the nickel, about 1 1 .50 wt% to about 1 4.00 wt% of the chromium, about 0.40 wt% to about 1 .00 wt% of the molybdenum, about 0.50 wt% or less of the copper, about 0.06 wt% or less of the cobalt, about 0.10 wt% or less of the tungsten, about 0.05 wt% or less of the vanadium, about 0.02 wt% or less of the nitrogen , and a balance of the iron and the impurities.

[0006] Embodiments of the disclosure may also provide a metal article including an at least partially heat treated metal composition. Prior to at least partially heat treating, the metal composition may include about 0.03 wt% or less of carbon, about 1 .00 wt% or less of manganese, about 0.015 wt% or less of sulfur, about 0.03 wt% or less of phosphorus, about 1 .00 wt% or less of silicon, about 3.50 wt% to about 4.50 wt% of nickel, about 1 1 .50 wt% to about 14.00 wt% of chromium, about 0.40 wt% to about 1 .00 wt% of molybdenum, about 0.50 wt% or less of copper, about 0.06 wt% or less of cobalt, about 0.10 wt% or less of tungsten, about 0.05 wt% or less of vanadium, about 0.02 wt% or less of nitrogen, and a balance of iron and impurities.

[0007] Embodiments of the disclosure may further provide a method for treating a metal article. The method may include heating the metal article to a first holding temperature of about 690°C. The metal article may include carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, and iron. The method may also include holding the metal article at the first holding temperature for at least about 10 hours. The method may further include cooling the metal article from the first holding temperature to a first cooling temperature of about 65°C or less. The method may also include heating the metal article to a second holding temperature of about 615°C, and holding the metal article at the second holding temperature for at least about 1 0 hours. The method may further include cooling the metal article from the second holding temperature to a second cooling temperature of about 65°C or less.

Brief Description of the Drawings

[0008] The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. [0009] The Figure illustrates a flowchart of a method for treating a metal article, according to one or more embodiments disclosed.

Detailed Description

[0010] It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.

[0011] Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Further, in the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to." All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term "or" is intended to encompass both exclusive and inclusive cases, i.e., "A or B" is intended to be synonymous with "at least one of A and B," unless otherwise expressly specified herein.

[0012] It has been surprisingly and unexpectedly discovered that combining carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, nitrogen, and iron produces a metal composition and/or a metal that meets or satisfies requirements of one or more NACE standards. For example, the metal composition and/or the metal surprisingly and unexpectedly satisfies the requirements of NACE standards for marine/off-shore environments and sour environments. It has further been surprisingly and unexpectedly discovered that treating (e.g., heat treating) a metal and/or a metal article having the metal composition according to one or more procedures disclosed herein provides a metal and/or a metal article that meets or satisfies allowable limits established by one or more NACE environments. For example, treating the metal and/or the metal article having the metal composition according to one or more of the heat treatments disclosed herein surprisingly and unexpectedly provides a metal and/or a metal article that satisfies the allowable limits established by NACE MR0175, NACE MR0103, and/or NACE TM0177.

[0013] Carbon may form carbides with one or components or elements of the metal composition and/or the metal. For example, carbon may form carbides with chromium in the metal composition and/or the metal. The formation of carbides may increase a strength and/or hardness of the metal. The formation of carbides may also decrease an amount or concentration of one or more components or elements of the metal composition and/or the metal. For example, the formation of carbides between carbon and chromium may decrease the amount of chromium in the metal composition and/or the metal. Carbon may be present in the metal composition and/or the metal in an amount of about 0.040 wt% or less, about 0.035 wt% or less, about 0.030 wt% or less, about 0.025 wt% or less, about 0.020 wt% or less, about 0.015 wt% or less, or about 0.010 wt% or less. It should be appreciated that all numerical values and ranges disclosed herein are approximate valves and ranges, whether "about" is used in conjunction therewith. It should also be appreciated that the term "about," as used herein, in conjunction with a numeral refers to a value that may be +/- 5% (inclusive) of that numeral, +/- 10% (inclusive) of that numeral, or +/- 1 5% (inclusive) of that numeral. It should further be appreciated that when a numerical range is disclosed herein, any numerical value falling within the range is also specifically disclosed.

[0014] Manganese may be a desulfurization agent in the metal composition and/or the metal. For example, manganese may be a desulfurization agent when present in the metal composition and/or the metal in an amount greater than about 0.050 wt% or greater than about 0.1 0 wt%. The presence of manganese in the metal composition and/or the metal may also decrease corrosion resistance of the metal in environments containing corrosive gases such as CO2 and/or H2S. Manganese may be present in the metal composition and/or the metal in an amount of about 1 .50 wt% or less, about 1 .40 wt% or less, about 1 .30 wt% or less, about 1 .20 wt% or less, about 1 .1 0 wt% or less, about 1 .00 wt% or less, about 0.90 wt% or less, about 0.80 wt% or less, or about 0.70 wt% or less.

[0015] Sulfur may increase stress corrosion cracking (SCC) and may decrease corrosion resistance. For example, an excess amount or concentration of sulfur may decease resistance to initiation and/or propagation of corrosion in the metal. Accordingly, in an exemplary embodiment, the presence of sulfur in the metal composition and/or the metal may be controlled or varied. For example, the metal composition and/or the metal may have a maximum sulfur concentration of about 0.01 5 wt%. In another example, sulfur may be present in the metal composition and/or the metal in an amount of about 0.025 wt% or less, about 0.020 wt% or less, about 0.01 5 wt% or less, about 0.01 0 wt% or less, or about 0.005 wt% or less.

[0016] Phosphorus may increase a strength of the metal. In excess, however, phosphorus may also reduce toughness of the metal. Accordingly, the presence of phosphorus in the metal composition and/or the metal may be varied. In at least one example, phosphorus may be present in the metal composition and/or the metal in an amount of about 0.040 wt% or less, about 0.035 wt% or less, about 0.030 wt% or less, about 0.025 wt% or less, about 0.020 wt% or less, or about 0.015 wt% or less.

[0017] Silicon may be a deoxidizer in the metal composition and/or the metal, and may increase a strength of the metal. An excess amount or concentration of silicon, however, may decrease a resistance to cracking and/or toughness of the metal. Accordingly, an amount of silicon present in the metal composition and/or the metal may be varied. For example, silicon may be present in the metal composition and/or the metal in an amount of about 1 .30 wt% or less, about 1 .20 wt% or less, about 1 .1 0 wt% or less, about 1 .00 wt% or less, about 0.90 wt% or less, about 0.80 wt% or less, or about 0.70 wt% or less.

[0018] Nickel may increase toughness and/or strength of the metal. For example, the presence of nickel in the metal composition and/or the metal may increase toughness of weld zones of the metal. Nickel may also promote the formation of one or more phases in the metal. For example, the presence of nickel may promote the formation of a martensite phase, a delta ferrite phase, or the like. The formation of the phases in the metal may be determined, at least in part, by the concentration of nickel. In at least one example, nickel may be present in an amount from about 3.0 wt%, about 3.1 wt%, about

3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, or about 4.0 wt% to about 4.1 wt%, about 4.2 wt%, about

4.3 wt%, about 4.4 wt%, about 4.5 wt%, about 4.6 wt%, about 4.7 wt%, about 4.8 wt%, about 4.9 wt%, or about 5.0 wt%. In another example, nickel may be present in an amount from about 3.0 wt% to about 5.0 wt%, about 3.1 wt% to about 4.9 wt%, about 3.2 wt% to about 4.8 wt%, about 3.3 wt% to about 4.7 wt%, about 3.4 wt% to about 4.6 wt%, about 3.5 wt% to about 4.5 wt%, about 3.6 wt% to about 4.4 wt% , about 3.7 wt% to about 4.3 wt%, about 3.8 wt% to about 4.2 wt%, or about 3.9 wt% to about 4.1 wt%.

[0019] Chromium may increase corrosion resistance of the metal. For example, the presence of chromium in the metal composition and/or the metal in an amount of about 1 0 wt% or greater may increase the corrosion resistance of the metal in environments containing corrosive gases (e.g., CO2 and/or H2S). In at least one example, chromium may be present in an amount from about 1 0.0 wt%, about 10.5 wt%, about 1 1 .0 wt%, about 1 1 .5 wt%, about 1 1 .75 wt%, about 12.0 wt%, about 1 2.25 wt%, or about 12.50 wt% to about 1 2.75 wt%, about 1 3.0 wt%, about 13.25 wt%, about 13.50 wt%, about 1 3.75 wt%, about 14.0 wt%, about 14.50 wt%, about 1 5.0 wt%, or about 1 6.0 wt%. In another example, chromium may be present in an amount of about 1 1 .0 wt% to about 1 4.50 wt%, about 1 1 .50 wt% to about 14.0 wt%, about 1 1 .75 wt% to about 1 3.75 wt%, about 1 2.0 wt% to about 1 3.50 wt%, about 12.25 wt% to about 13.25 wt% , or about 1 2.50 wt% to about 13.0 wt%.

[0020] Molybdenum may increase corrosion resistance of the metal. Molybdenum may also promote the formation of one or more phases, such as a ferrite phase. In at least one example, molybdenum may be present in an amount from about 0.20 wt%, about 0.25 wt%, about 0.30 wt%, about 0.35 wt%, about 0.40 wt%, about 0.45 wt%, about 0.50 wt%, about 0.55 wt%, about 0.60 wt%, about 0.65 wt%, or about 0.70 wt% to about 0.75 wt%, about 0.80 wt%, about 0.85 wt%, about 0.90 wt%, about 0.95 wt%, about 1 .0 wt%, about 1 .05 wt%, about 1 .10 wt%, about 1 .1 5 wt%, or about 1 .20 wt%. In at least one example, molybdenum may be present in an amount from about 0.20 wt% or greater, about 0.25 wt% or greater, about 0.30 wt% or greater, about 0.35 wt% or greater, about 0.40 wt% or greater, about 0.45 wt% or greater, about 0.50 wt% or greater, about 0.60 wt% or greater, about 0.65 wt% or greater, or about 0.70 wt% or greater. In at least one example, molybdenum may be present in an amount from about 0.75 wt% or less, about 0.80 wt% or less, about 0.85 wt% or less, about 0.90 wt% or less, about 0.95 wt% or less, about 1 .0 wt% or less, about 1 .05 wt% or less, about 1 .1 0 wt% or less, about 1 .1 5 wt% or less, or about 1 .20 wt% or less. In another example, molybdenum may be present in an amount of about 0.30 wt% to about 1 .1 0 wt%, about 0.35 wt% to about 1 .05 wt%, about 0.40 wt% to about 1 .00 wt%, about 0.45 wt% to about 0.95 wt%, about 0.50 wt% to about 0.90 wt%, about 0.55 wt% to about 0.85 wt%, about 0.60 wt% to about 0.80 wt%, or about 0.65 wt% to about 0.75 wt%.

[0021] Copper may increase a strength and corrosion resistance of the metal. Copper may also decrease a workability (e.g. , hot workability) of the metal. For example, an excess amount of copper in the metal composition and/or the metal may decrease the hot workability of the metal. Accordingly, an amount of copper present in the metal composition and/or the metal may be varied to control the properties of the metal. In at least one example, copper may be present in the metal composition and/or the metal in an amount of about 0.60 wt% or less, about 0.55 wt% or less, about 0.50 wt% or less, about 0.45 wt% or less, about 0.40 wt% or less, about 0.35 wt% or less, or about 0.30 wt% or less.

[0022] Cobalt may improve tempering and hardness, and may also decrease toughness of the metal. In at least one example, cobalt may be present in the metal composition and/or the metal in an amount of about 0.075 wt% or less, about 0.070 wt% or less, about 0.065 wt% or less, about 0.060 wt% or less, about 0.055 wt% or less, about 0.050 wt% or less, about 0.045 wt% or less, about 0.040 wt% or less, about 0.035 wt% or less, or about 0.030 wt% or less.

[0023] Tungsten, similar to copper, may increase a strength and corrosion resistance of the metal. Tungsten may also decrease a workability of the metal. For example, an excess amount of tungsten may decrease the hot workability of the metal. Accordingly, an amount of tungsten present in the metal composition and/or the metal may be varied to control the properties of the metal. In at least one example, tungsten may be present in the metal composition and/or the metal in an amount of about 0.20 wt% or less, about 0.1 5 wt% or less, about 0.14 wt% or less, about 0.1 3 wt% or less, about 0.1 2 wt% or less, about 0.1 1 wt% or less, about 0.09 wt% or less, about 0.08 wt% or less, about 0.07 wt% or less, about 0.06 wt% or less, or about 0.05 wt% or less.

[0024] Vanadium may increase resistance to SCC and/or a strength of the metal. Vanadium may increase resistance to cracking and/or the strength of the metal by promoting the precipitation of one or more elements or components of the metal composition and/or the metal within grains. Vanadium may also increase resistance to cracking and/or the strength of the metal by preventing the precipitation of one or more elements of the metal composition and/or the metal at grain boundaries. For example, vanadium may promote uniform precipitation of carbides and nitrides within grains of the metal. Vanadium may also increase resistance to strain age hardening. In at least one example, vanadium may be present in the metal composition and/or the metal in an amount of about 0.10 wt% or less, about 0.09 wt% or less, about 0.08 wt% or less, about 0.07 wt% or less, about 0.06 wt% or less, about 0.05 wt% or less, about 0.04 wt% or less, about 0.03 wt% or less, about 0.02 wt% or less, or about 0.01 wt% or less. [0025] Nitrogen may form compounds with one or more elements or compounds of the metal composition and/or the metal. For example, nitrogen may form compounds with chromium, thereby decreasing an amount of free chromium in the metal composition and/or the metal. Nitrogen may also promote the formation of one or more phases (e.g., delta ferrite phase) in the metal. Nitrogen may also increase a hardness of the metal. For example, nitrogen may increase the hardness of the metal when present in an amount of about 0.02 wt% or greater. Nitrogen may decrease corrosion resistance, SCC resistance, and toughness of the metal, and may further increase strain age hardening of the metal. For example, tempering the metal having nitrogen in an amount of about 0.02 wt% or greater may result in the formation of nitrides, which may decrease corrosion resistance, SCC resistance, and toughness. Accordingly, the concentration or amount of nitrogen present in the metal composition and/or the metal may be varied to control the properties of the metal. In at least one example, nitrogen may be present in the metal composition and/or the metal in an amount of about 0.020 wt% or less, about 0.019 wt% or less, about 0.018 wt% or less, about 0.01 7 wt% or less, about 0.01 6 wt% or less, about 0.015 wt% or less, about 0.01 4 wt% or less, about 0.013 wt% or less, about 0.01 2 wt% or less, about 0.01 1 wt% or less, or about 0.010 wt% or less.

[0026] A balance or remainder of the metal composition and/or the metal may include or consist essentially of iron and/or one or more impurities (e.g., unavoidable impurities or byproducts). The impurities may result from one or more of the processes of making or producing the metal composition and/or the metal. An amount or concentration of the impurities may be varied so as to not adversely affect one or more properties of the metal. For example, the impurities may be present in the metal composition and/or the metal in an amount of about 0.60 wt% or less, about 0.55 wt% or less, about 0.50 wt% or less, about 0.45 wt% or less, about 0.40 wt% or less, about 0.35 wt% or less, or about 0.30 wt% or less.

[0027] A respective concentration or amount of each of the elements or components present in the metal composition and/or the metal may be varied to control one or more properties of the metal. For example, the respective concentrations of carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, nitrogen, iron, and/or the impurities may be varied to control corrosion resistance, the formation of one or more phases (e.g. , delta ferrite phases, gamma phases, etc.), hardness, toughness, strength, or the like, or any combination thereof. In an exemplary embodiment, the metal composition and/or the metal may include about 0.03 wt% or less of carbon, about 1 .00 wt% or less of manganese, about 0.015 wt% or less of sulfur, about 0.03 wt% or less of phosphorus, about 1 .00 wt% or less of silicon, about 3.50 wt% to about 4.50 wt% of nickel, about 1 1 .50 wt% to about 1 4.00 wt% of chromium, about 0.40 wt% to about 1 .00 wt% of molybdenum, about 0.50 wt% or less of copper, about 0.06 wt% or less of cobalt, about 0.1 0 wt% or less of tungsten, about 0.05 wt% or less of vanadium, about 0.02 wt% or less of nitrogen, about 0.50 wt% or less of the impurities or byproducts, and a balance of iron.

[0028] The metal composition and/or the metal may be made by alloying, mixing, or otherwise combining carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, nitrogen, and/or iron with one another. Carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, nitrogen, and/or iron may be combined or alloyed with one another in any order or sequence. Carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, nitrogen, and/or iron may be alloyed via any one or more processes known in the art. For example, carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, nitrogen, and/or iron may be heated or melted to a molten solution via one or more melting or foundry processes, and the molten solution may be solidified to the metal or a metal article (e.g. , slabs or billets) containing the metal through one or more casting processes, molding processes, forging processes, or the like. Illustrative melting processes may include, but are not limited to, a converter process, a furnace process (e.g., an electric arc furnace process), a blending process, or the like.

[0029] The metal article may be any metal component, part, piece, or the like. For example, the metal article may be a metal slab or billet. In another example, the metal article may be a turbomachine or a turbomachine component. Illustrative turbomachines may include, but are not limited to, single- or multi-stage centrifugal compressors, single- or multi-stage steam turbines, single- or multi-stage gas turbines, single- or multi-stage expanders, single- or multi-stage reciprocating compressors, rotating separators, supersonic compressors, pumps, gas engines, diesel engines, or the like. Illustrative turbomachine components may include, but are not limited to, impellers, blades, vanes, casings, diaphragms, stators, mechanical fasteners, bearings, heads, pistons, cylinders, rods, shafts, rotary shafts, sleeves, balance pistons, cross- heads, piston rods, connecting rods, crankcases, engine blocks, turbine discs, shroud rings, nose cones, inlet cases, exhaust cases, intermediate casings, valve blocks, nozzle blocks, inlet nozzles, discharge or outlet nozzles, inlet walls, division walls, discharge walls, labyrinth seals, or the like.

[0030] The metal article and/or the metal thereof may be treated to control and/or adjust one or more properties of the metal article and/or the metal thereof. For example, the metal article and/or the metal may be subjected to one or more heat treatments to control and/or adjust one or more properties (e.g. , toughness, strength, hardness, etc.) thereof. The heat treatments may control a maximum hardness of the metal article and/or the metal thereof. The heat treatments may include tempering the metal article and/or the metal thereof. For example, the heat treatments may include a first tempering and a second tempering.

[0031] The first tempering may include heating the metal article in a furnace to a holding temperature. The holding temperature may be from about 682°C, about 684°C, about 686°C, or about 688°C to about 692°C, about 694°C, about 696°C, or about 698°C. For example, the holding temperature may be about 682°C to about 698°C, about 684°C to about 696°C, about 686°C to about 694°C, about 688°C to about 692°C, or about 697°C to about 691 °C. In an exemplary embodiment, the holding temperature may be about 690°C.

[0032] In the first tempering, the metal article may be held at the holding temperature for any amount of time or duration. The duration in which the metal article may be held at the holding temperature may be at least partially determined by a thickness (e.g., maximum thickness) of the metal article. For example, a metal article having a maximum thickness of about 1 2.7 cm or less may be held at the holding temperature for a duration of about 9 hours or more, about 9.5 hours or more, about 1 0 hours or more, or about 1 0.5 hours or more. In another example, a metal article having a maximum thickness of about 12.7 cm or less may be held at the holding temperature for a minimum duration of about 9 hours, about 9.5 hours, about 10 hours, or about 10.5 hours. In another example, a metal article having a maximum thickness of about 12.7 cm or greater may be held at the holding temperature for a duration of about 1 0 hours or more. In at least one embodiment, the duration in which a metal article having a maximum thickness greater than about 1 2.7 cm may be held at the holding temperature may be increased by one hour or one hour increments for each additional 2.54 cm of thickness or fraction thereof greater than or in excess of about 12.7 cm .

[0033] In at least one embodiment, the first tempering may include heating the metal article in the furnace from about ambient temperature (e.g. , room temperature) to the holding temperature. In another embodiment, the first tempering may include disposing the metal article in a furnace having a temperature between about 205°C and about 315°C, holding the metal article in the furnace at a temperature between about 205°C and about 31 5°C for a predetermined period, and subsequently heating the metal article to the holding temperature. The amount of time or duration in which the metal article may be held in the furnace at a temperature between about 205°C and about 31 5°C may be determined, at least in part, by a thickness of the metal article. For example, the duration the metal article may be held in the furnace at a temperature between about 205°C and about 315°C may be about one hour for each 2.54 cm of thickness, with a minimum duration of about 3 hours.

[0034] In the first tempering, the metal article may be heated from about ambient temperature or from a temperature between about 205°C and about 31 5°C to the holding temperature at any heating rate. The heating rate may be determined, at least in part, by a thickness (e.g., maximum thickness) of the metal article. For example, a metal article having a maximum thickness of about 10.1 6 cm or less may be heated to the holding temperature (e.g., about 690°C) at a heating rate of about 225°C per hour or lower. In another example, a metal article having a maximum thickness of about 1 0.1 6 cm or greater may be heated to the holding temperature (e.g. , about 690°C) at a heating rate of about 55°C per hour or lower.

[0035] The first tempering may also include cooling the metal article from the holding temperature to or below a resting or cooling temperature. The cooling temperature may be from about 55°C, about 60°C, or about 65°C to about 70°C, about 75°C, about 80°C, or greater. In another example, the cooling temperature may be greater than about 55°C, greater than about 60°C, greater than about 65°C, greater than about 70°C, greater than about 75°C, or greater than about 80°C. The metal article may be cooled from the holding temperature to or below the cooling temperature in the furnace. An atmosphere of the furnace may be controlled to prevent or substantially prevent oxidation of the metal article and/or the metal thereof during one or more heating and/or cooling processes. For example, the furnace may be filled or purged with an inert gas to reduce or prevent oxidation of the metal article during the one or more heating and/or cooling processes.

[0036] In the first tempering, the metal article may be cooled from the holding temperature to or below the cooling temperature at any cooling rate. The cooling rate may be determined, at least in part, by a thickness (e.g., maximum thickness) of the metal article. For example, a metal article having a maximum thickness of about 2.54 cm or less may be cooled from the holding temperature to the cooling temperature (e.g., about 65°C or greater) at a cooling rate of about 275°C per hour or lower. In another example, a metal article having a maximum thickness of about 12.7 cm or greater may be cooled from the holding temperature to or below the cooling temperature at a cooling rate of about 55°C per hour. In another example, a metal article having a maximum thickness between about 2.54 cm and about 12.7 cm may be cooled from the holding temperature to or below the cooling temperature at a cooling rate of about 275°C per hour divided by the maximum thickness of the metal article.

[0037] The first tempering may also include cooling the metal article from the cooling temperature to ambient temperature (e.g. , room temperature). As previously discussed, the metal article may be cooled from the holding temperature to or below the cooling temperature in the furnace where the environment may be controlled. In the first tempering, the metal article may be cooled from the cooling temperature to ambient temperature (e.g., room temperature) outside of the furnace in an open environment.

[0038] The metal article may be held at ambient temperature for any amount of time or duration. The duration in which the metal article may be held at ambient temperature may be at least partially determined by a thickness (e.g., maximum thickness) of the metal article. For example, a metal article having a maximum thickness or about 12.7 cm or less may be held at ambient temperature for minimum of about 24 hours or less. In another example, a metal article having a maximum thickness of about 1 2.7 cm or less may be held at ambient temperature for about 36 hours or less, about 32 hours or less, about 28 hours or less, or about 26 hours or less. In another example, a metal article having a maximum thickness of about 1 2.7 cm or greater may be held at the holding temperature for a duration of about 24 hours or greater. In at least one embodiment, the duration in which a metal article having a maximum thickness greater than about 12.7 cm may be held at the holding temperature may be increased by five hours or five hour increments for each additional 2.54 cm of the thickness or fraction thereof in excess of about 1 2.7 cm.

[0039] The second tempering may include heating the metal article in a furnace to a holding temperature. The holding temperature may be from about 607°C, about 608°C, about 61 0°C, about 612°C, or about 614°C to about 616°C, about 61 8°C, about 620°C, about 622°C, or about 623°C. For example, the holding temperature may be about 607°C to about 623°C, about 608°C to about 622°C, about 61 0°C to about 620°C, about 612°C to about 618°C, or about 614°C to about 616°C. In an exemplary embodiment, the holding temperature may be about 61 5°C.

[0040] In the second tempering, the metal article may be held at the holding temperature for any amount of time or duration. The duration in which the metal article may be held at the holding temperature may be at least partially determined by a thickness (e.g., maximum thickness) of the metal article. For example, a metal article having a maximum thickness of about 1 2.7 cm or less may be held at the holding temperature for a duration of about 9 hours or more, about 9.5 hours or more, about 1 0 hours or more, or about 10.5 hours or more. In another example, a metal article having a maximum thickness of about 12.7 cm or less may be held at the holding temperature for a minimum duration of about 9 hours, about 9.5 hours, about 10 hours, or about 10.5 hours. In another example, a metal article having a maximum thickness or about 1 2.7 cm or greater may be held at the holding temperature for a duration of about 1 0 hours or more. In at least one embodiment, the duration in which a metal article having a maximum thickness greater than about 1 2.7 cm may be held at the holding temperature may be increased by one hour or one hour increments for each additional 2.54 cm of thickness or fraction thereof in excess of about 12.7 cm.

[0041] In at least one embodiment, the second tempering may include heating the metal article in the furnace from about ambient temperature (e.g. , room temperature) to the holding temperature. In another embodiment, the second tempering may include disposing the metal article in a furnace having a temperature between about 205°C and about 315°C, holding the metal article in the furnace at a temperature between about 205°C and about 31 5°C for a predetermined period, and subsequently heating the metal article to the holding temperature. The amount of time or duration in which the metal article may be held in the furnace at a temperature between about 205°C and about 315°C may be determined, at least in part, by a thickness of the metal article. For example, the duration the metal article may be held in the furnace at a temperature between about 205°C and about 315°C may be about one hour for each 2.54 cm of thickness, with a minimum duration of about 3 hours.

[0042] In the second tempering, the metal article may be heated from about ambient temperature or from a temperature between about 205°C and about 31 5°C to the holding temperature at any heating rate. The heating rate may be determined, at least in part, by a thickness (e.g., maximum thickness) of the metal article. For example, a metal article having a maximum thickness of about 10.1 6 cm or less may be heated to the holding temperature (e.g., about 61 5°C) at a heating rate of about 225°C per hour or lower. In another example, a metal article having a maximum thickness of about 1 0.1 6 cm or greater may be heated to the holding temperature (e.g. , about 61 5°C) at a heating rate of about 55°C per hour or lower.

[0043] The second tempering may also include cooling the metal article from the holding temperature to or below a resting or cooling temperature. The cooling temperature may be from about 55°C, about 60°C, or about 65°C to about 70°C, about 75°C, about 80°C, or greater. In another example, the cooling temperature may be greater than about 55°C, greater than about 60°C, greater than about 65°C, greater than about 70°C, greater than about 75°C, or greater than about 80°C. The metal article may be cooled from the holding temperature to or below the cooling temperature in the furnace. As previously discussed, the atmosphere of the furnace may be controlled to prevent or substantially prevent oxidation of the metal article during one or more heating and/or cooling processes.

[0044] In the second tempering, the metal article may be cooled from the holding temperature to or below the cooling temperature at any cooling rate. The cooling rate may be determined, at least in part, by a thickness of the metal article. For example, a metal article having a maximum thickness of about 2.54 cm or less may be cooled from the holding temperature to the cooling temperature (e.g., about 65°C or greater) at a cooling rate of about 275°C per hour or lower. In another example, a metal article having a maximum thickness of about 1 2.7 cm or greater may be cooled from the holding temperature to or below the cooling temperature at a cooling rate of about 55°C per hour or lower. In another example, a metal article having a maximum thickness between about 2.54 cm and about 12.7 cm may be cooled from the holding temperature to or below the cooling temperature at a cooling rate of about 275°C per hour divided by the maximum thickness of the metal article.

[0045] The second tempering may also include cooling the metal article from the cooling temperature to ambient temperature (e.g. , room temperature). As previously discussed, the metal article may be cooled from the holding temperature to or below the cooling temperature in the furnace where the environment may be controlled. In the second tempering, the metal article may be cooled from the cooling temperature to ambient temperature (e.g., room temperature) outside of the furnace in an open environment.

[0046] Treating the metal article and/or the metal thereof according to the heat treatments described herein may provide a metal article or a metal that satisfies or meets allowable limits established by one or more NACE specific environments, such as NACE MR01 75, NACE MR01 03, and/or NACE TM0177. In at least one embodiment, the metal article and/or the metal thereof may have a hardness greater than, less than, or substantially equal to allowable limits established by NACE. For example, treating the metal article and/or the metal thereof according to the first tempering and the second tempering described herein may provide the metal article and/or the metal thereof with a Rockwell hardness C (HRC) of about 23 HRC or greater. In another example, treating the metal article and/or the metal thereof according to the first tempering and the second tempering described herein may provide the metal article and/or the metal thereof with a Rockwell hardness C (HRC) of about 23 HRC or less. The metal article and/or the metal thereof may have an HRC less than about 23 HRC, less than about 22 HRC, less than about 21 HRC, or less than about 20 HRC. In another example, treating the metal article and/or the metal thereof according to the first tempering and the second tempering described herein may provide the metal article and/or the metal thereof with a Brinell hardness (HBW) of about 255 HBW or less. In yet another example, the metal article and/or the metal thereof may have an HBW less than about 255 HBW, less than about 250 HBW, less than about 245 HBW, or less than about 240 HBW. In at least one example, treating the metal article and/or the metal thereof according to the first tempering and the second tempering described herein may provide the metal article and/or the metal thereof with a Brinell hardness (HBW) of about 255 HBW or greater.

[0047] The Figure illustrates a flowchart of a method 100 for treating a metal article, according to one or more embodiments. The metal article may include carbon, manganese, sulfur, phosphorus, silicon, nickel, chromium, molybdenum, copper, cobalt, tungsten, vanadium, and iron. The method 100 may include heating the metal article to a first holding temperature of about 690°C, as shown at 102. The method 100 may also include holding the metal article at the first holding temperature for at least about 10 hours, as shown at 1 04. The method 1 00 may further include cooling the metal article from the first holding temperature to a first cooling temperature of about 65°C or less, as shown at 106. The method 100 may also include heating the metal article to a second holding temperature of about 615°C, as shown at 1 08. The method 100 may also include holding the metal article at the second holding temperature for at least about 10 hours, as shown at 1 10. The method 1 00 may further include cooling the metal article from the second holding temperature to a second cooling temperature of about 65°C or less, as shown at 1 12.

[0048] The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.