| 摘要 |
PURPOSE:To manufacture a steel material having superior resistance to hydrogen induced cracking, high strength, ductility and toughness by adding specified percentages of C, Si and Mn and providing a metallic structure consisting of specified phases. CONSTITUTION:A steel material contg., by weight, 0.01-0.50% C, <=2.0% Si and 0.3-3.0% Mn or further contg. at least one among 0.005-0.2% Nb, 0.005-0.4% Ti and 0.005-0.4% V is prepd. The steel material has a metallic structure consisting of a polygonal ferrite phase of <=10mum average grain size and a ferrite phase contg. uniformly dispersed acicular martensite, bainite or a mixture thereof. The dispersed phase is a phase produced by transformation at a low temp.
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