摘要
利用Gleeble—1500热模拟试验机进行1 000 MPa低碳QT钢不同焊接热输入的热模拟试验,研究了焊接热影响区粗晶区(CGHAZ)组织与韧性及其变化规律.结果表明,一次热循环后,随着热输入的增加,冲击韧度先是增加然后下降,组织由马氏体向马氏体(M)与贝氏体(B)的混合组织转变,粗大的M和B组织及板条间和板条内碳化物的存在是造成韧度下降的主要原因.经历峰值温度为900℃二次热循环后的韧性并不都具有改善作用,其原因与晶粒和组织遗传现象有关.热输入小时发生晶粒和组织遗传,热输入大时只产生晶粒遗传,粗大贝氏体的形成和碳化物进一步析出是大热输入二次热循环恶化韧性的主要原因.
The microstructure and toughness of the coarse-grained welding heat-affected zone(CGHAZ) of 1 000 MPa low carbon QT steel with different heat input were investigated by thermal simulation with a Gleeble-1500 thermal simulator.The results show that the impact toughness firstly increases and then decreases and the microstructure varies from martensite to duplex structure of matensite and bainite with the welding heat input being increased in the first welding thermal cycle.The decrease of the toughness was caused by the presence of carbide in coarse lath martensite and bainite.All the effect of the second thermal cycle with 900 ℃ peak temperature on toughness is not improved because of the inheritance of grain and microstructure.There is an inheritance of grain and microstructure at low welding heat input,and there is only an inheritance of grain at high welding heat input.The main reason to cause the decrease of the toughness is the formation of the coarse bainite and precipitation carbide in the second thermal cycle at high welding heat input.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2011年第5期97-100,118,共4页
Transactions of The China Welding Institution
关键词
高强钢
焊接热输入
焊接热影响区
冲击韧度
显微组织
high strength steel
welding heat input
heat-affected zone
toughness
microstructure
