PURPOSE: To produce an electric welded oil well pipe having low hardness and high yield strength by subjecting a steel contg. a specific compsn. amt. of C, Si, Mn and Nb to hot rolling and coiling at a low temp. then to pipe making under strong pressing down and heat treatment under adequate conditions.
CONSTITUTION: A steel contg. 0.12W0.22% C, ≤0.5% Si, 1.0W2.0% Mn and ≤0.050% Nb as essential components, contg. further ≥1 kinds among ≤0.050% Al, ≤0.050% V and ≤0.040% Ti if necessary and consisting of the balance Fe and unavoidable impurities is hot rolled at a finishing temp. of 740W830°C and is then quickly cooled at an average cooling rate of ≥150°C/sec and is coiled at ≤500°C. The rolled steel is then made into an electric welded pipe under the strong pressing down to ≥3% longitudinal strain. The pipe is held for 30secW 30min at 100W550°C, by which the electric welded pipe having the yield strength and HRC hardness in the range enclosed by the four straight lines: AB; y=2x+ 33, BC; y=80, CD; y=2x+41, DA; y=70 in the figure, low hardness and the high yield strength is obtd.
CHIYANO ZENSAKU
YAMAMOTO KOUJI
| JPS5819462A | 1983-02-04 | |||
| JPS5633425A | 1981-04-03 | |||
| JPS5521517A | 1980-02-15 | |||
| JPS5385711A | 1978-07-28 | |||
| JPS52103314A | 1977-08-30 | |||
| JPS51111418A | 1976-10-01 | |||
| JPS5067715A | 1975-06-06 | |||
| JPS57131319A | 1982-08-14 | |||
| JPS6024321A | 1985-02-07 |