PRODUCTION OF NON-HEAT TREATED HIGH TENSILE-STRENGTH STEEL EXCELLENT IN LOW TEMPERATURE TOUGHNESS,申请号JP19970112244-传众专利搜索

PRODUCTION OF NON-HEAT TREATED HIGH TENSILE-STRENGTH STEEL EXCELLENT IN LOW TEMPERATURE TOUGHNESS

申请公布号：JPH10306315(A)

申请号：JP19970112244

申请日期：1997.04.30

申请公布日期：1998.11.17

申请人：

KAWASAKI STEEL CORP

发明人：OMORI AKIO;MORIKAGE YASUSHI;OI KENJI;KAWABATA FUMIMARU;AMANO KENICHI

分类号：C21D8/00;C21D9/00;C22C38/00;C22C38/12;C22C38/58;(IPC1-7):C21D8/00

主分类号：C21D8/00

摘要：PROBLEM TO BE SOLVED: To obtain a steel having high tensile strength and excellent in low temp. toughness without adding a large amt. of expensive elements by subjecting a stock having a specified compsn. to hot working under specified conditions to form into an approximately prescribed shape, thereafter subjecting it to air cooling to a specified temp., executing hot working, holding it at a specified temp. range and subsequently executing air cooling. SOLUTION: A stock having a compsn. contg. C, Si, Mn, P, S, Al, V and N, also satisfying 4.0 to 12.0 V/N, and the balance Fe or the like is heated at 1050 to 1250 deg.C and is subjected to hot working at a cumulative draft of >=30% in the temp. range of 1050 to 950 deg.C to form into an approximately prescribed shape. Next, It is air-cooled to a temp. T ( deg.C) satisfying the inequality and is hot-worked at a draft of <=5%. In the formula, Tps is calculated from the relation among the contents of V, N and Ti. Then, it is held or retained in the temp. range of the temp. T ( deg.C) or below to the Ar3 point or above for >=160 sec, the nitrides having 0.02 to 0.20μm particle size are dispersed into austenite at the density of 10<5> to 10<10> pieces/mm<3> , and after that, it is air-cooled to a room temp.