轧制工艺对V-N-Ti钢焊接粗晶热影响区组织和韧性的影响  

Effect of rolling process on microstructure and toughness of coarse grain heat affected zone of V-N-Ti steel

作　　者：师仲然 赵和明 杨海峰 王川 王天琪 潘涛[1] SHI Zhong-ran;ZHAO He-ming;YANG Hai-feng;WANG Chuan;WANG Tian-qi;PAN Tao(Department of Structural Steels,Central Iron and Steel Research Institute,Beijing 100081,China;Minmetals Yingkou Medium Plate Co.,Ltd.,Yingkou 115000,Liaoning,China)

机构地区：[1]钢铁研究总院工程用钢研究所,北京100081 [2]五矿营口中板有限责任公司,辽宁营口115000

出　　处：《中国冶金》2021年第3期66-72,共7页China Metallurgy

摘　　要：为了分析大线能量焊接下接头低温韧性的影响因素,研究轧制工艺对V-N-Ti钢粗晶热影响区(CGHAZ)组织和韧性的影响。试验结果表明,当终轧温度从950降低到800℃,且t8/5(从800冷却到500℃的时间)为180s时,CGHAZ中铁素体面积百分数从91.2%降低到53.9%,贝氏体面积百分数从0%增加到31.1%,-20℃冲击功从182降低到92J。上述现象是由于终轧温度影响了母材中尺寸为30~70nm的富Ti-(Ti,V)(C,N)粒子的成分。与低温终轧相比,高终轧温度条件下母材中富Ti-(Ti,V)(C,N)粒子的V元素含量较高,这使其在焊接加热过程中更易发生溶解,并在焊接冷却过程中以细小富Ti-(Ti,V)(C,N)析出,钉扎奥氏体晶界;焊接冷却过程中,富Ti-(Ti,V)(C,N)可以作为V元素的析出核心促进VN的析出,提高了其铁素体形核能力,改善了CGHAZ组织和韧性。In order to analyze the influencing factors of low temperature toughness of joints under high heat input welding,the effect of rolling process on microstructure and toughness of coarse grain heat-affected zones(CGHAZ)of V-N-Ti steel was analyzed.The results showed that when the final rolling temperature was decreased from 950to 800℃and t8/5(the time from 800to 500℃)is 180s,the area fraction of ferrite in CGHAZ was reduced from 91.2%to 53.9%,bainite was increased from 0to 31.1%,and the impact energy of CGHAZ at-20℃was reduced from 182to 92J.The reason for the change was that the final rolling temperature affected the composition of Ti-rich(Ti,V)(C,N)particles with a base material size of 30-70nm in experimental steel.Compared with low-temperature finishing rolling,vanadium content of Ti-rich(Ti,V)(C,N)particles in the base metal under high finishing temperature conditions was higher,which made it easier to dissolve during welding heating process and re-precipitate as fine Ti-rich(Ti,V)(C,N)during cooling stage of welding to pin the austenite grain boundaries.During welding cooling process,Ti-rich(Ti,V)(C,N)can be used as the precipitation core of vanadium to promote precipitation of VN,increase the ferrite nucleation potency,and improve the CGHAZ microstructure and toughness.

关 键 词：V-N-Ti微合金钢 终轧温度 CGHAZ 铁素体 富Ti-(Ti V)(C N) 

分 类 号：TG335[金属学及工艺—金属压力加工] TG407[交通运输工程—船舶及航道工程] U671.8[交通运输工程—船舶与海洋工程]