原始组织对690MPa级海工钢亚温淬火后强韧性的影响  

Effect of original structure on strength and toughness of 690MPa grade marine engineering steel after intercritical quenching

作　　者：王通 张朋 王九清 庞辉勇 龙杰 赵喜伟 WANG Tong;ZHANG Peng;WANG Jiu-qing;PANG Hui-yong;LONG Jie;ZHAO Xi-wei(Wusteel Company,HBIS Group,Wugang 462500,Henan,China)

机构地区：[1]河钢集团舞钢公司,河南舞钢462500

出　　处：《钢铁》2020年第12期72-80,共9页Iron and Steel

基　　金：国家重点研发计划资助项目(2016YFB0300601)。

摘　　要：为了稳定亚温淬火工艺与工业化生产,通过力学性能分析及显微组织观察,对比了正火+亚温淬火+回火、在线淬火+亚温淬火+回火、离线淬火+亚温淬火+回火3种热处理工艺对690 MPa级海洋工程用钢板组织性能的影响。结果表明,采用离线淬火+亚温淬火+回火工艺结果最理想,能够大幅度提高钢板的低温冲击性能和伸长率。同时,还能够获得较低的屈强比,断口形貌全部为韧窝,呈明显的韧性断裂,而且随着亚温保温时间的增加,强度逐渐提高,当保温时间达到30min以后,强度及条片状铁素体基本不发生变化;采用直接淬火态+亚温淬火+回火虽然可以保证高强度低屈强比,但是冲击功表现较为离散,稳定性欠佳,断口形貌为混合型,以韧性断裂为主;采用正火态+亚温淬火+回火工艺效果最差,尤其是不能保证钢板低温韧性,断口形貌全部为解理,呈明显的脆性断裂,其中片条状铁素体形貌是决定优良低温冲击性能的关键因素。In order to stabilize the intercritical temperature quenching process and industrial production,effect of three different heat treatment processes,including normalizing+intercritical quenching+tempering,on-line quenching+intercritical quenching+tempering,off-line quenching+intercritical quenching+tempering,on the microstructure and mechanical properties of 690 MPa grade marine engineering steel plate was studied.The results show that the optimal process is the off-line quenching+intercritical quenching+tempering,which greatly improve the low temperature impact toughness and elongation of steel plate with ensuring high strength and low yield ratio.The fracture morphology is all dimples and shows obvious ductile fracture.With the increase of holding time,the strength increases gradually,but the strength and lamellar ferrite change slightly when the holding time exceeds 30 min.Although high strength and low yield ratio can be guaranteed by on-line quenching+intercritical quenching+tempering,the impact energy shows relatively discrete and the stability is poor.The fracture morphology is mixed,mainly ductile fracture.The normalizing+intercritical quenching+tempering is the least effective especially for the low temperature impact toughness of steel plate.The fracture morphology is cleavage and shows clear brittle fracture.The strip ferrite morphology is the key factor of determining the low temperature toughness of the steel plate.

关 键 词：亚温淬火 海工钢 低温韧性 伸长率 断口形貌 

分 类 号：TG142.1[一般工业技术—材料科学与工程]