PURPOSE: To prevent the weld crack of the time when joining and welding the titled alloy material of the specific composition along and a restraining material by preheating this alloy to the specific temperature prior to welding etc.
CONSTITUTION: The Cu-Ni-Si alloy comprising ≤1.1% Si based on weight, ≤4.5% Ni and Cu and unavoidable impurities for the remainder is preheated to ≥TP°C of the formula prior to welding. Here, γ denotes the maximum amount of silicide that can be deposited in that alloy. Next, this alloy alone or this alloy and a restraining material of, for example, stainless steel, is joined by pressure contacting and are welded. When the Si and Ni in the alloy to be welded exceed the above-described amounts respectively, weld crack is apt to occur despite preheating to a predetermined temperature. If the preheating temperature TP is below the above-described value, rupture draw decreases and the crack along the crystal grain boundaries of metal structure is shown by the action of tensile stress.
SAKAMOTO MASAHIKO
KIRIHARA SEISHIN
