PURPOSE: To obtain a steel material of high sulfide stress corrosion cracking resistance even with steel materials of ordinary components by heating a blank material worked to the sectional size approximate to the section of products to specific temps., and subjecting this to hardening and tempering immediately after rolling at specific reduction of area.
CONSTITUTION: A steel material such as steel pipe which consists, by wt%, of 0.15W 0.40 C, 0.1W1.0 Si, 0.4W2.0 Mn, 0.01W0.10 Al and the balance Fe and unavoidable impurities, and is worked to the sectional shape and size approximate to the sectional shape of products is used as a blank material. Such material is heated to temps. above the Ac3 tranformation point and below the temp. at which the formation of coarse austenite crystal grains initiates, and is hot rolled in such a way that the reduction of area R determined by the equation (S1, S2 are respectively the sectional areas at a right angle to the main rolling direction before and after the hot rolling) attains 0.015. Right after the rolling, the material is hardened then tempered at temps. below the Ac1 transformation point. Then the crystal grains are fined, nonmetallic inclusions are spread and parted, and hydrogen is dispersed and adsorbed, whereby the intended steel material is obtained.
UENO TAKEO
EJIMA AKIO
| JPS52152814A | 1977-12-19 |