摘要
采用Gleeble1500热模拟机,物理模拟中国低活化马氏体(CLAM)钢焊接热影响区粗晶区(CGHAZ)的冷却过程,结合组织观察、Thermo-calc热力学软件计算和硬度测试等手段分析了冷速ωc对CGHAZ的组织演变及硬度的影响,并绘制了CLAM钢的SH-CCT图。结果表明:CLAM钢的CGHAZ中过冷奥氏体仅发生低温板条马氏体(LM)及先共析铁素体(α铁素体)转变。0.25℃/s为CGHAZ过冷奥氏体发生完全LM相变的临界冷速。当ωc>0.25℃/s时,CGHAZ的组织除LM外,还含有少量的δ铁素体,δ铁素体是δ→γ相变阶段转变不充分而残留至室温的组织,在该冷速范围内粗晶区的组织形态变化不明显。当ωc<0.25℃/s时,由于发生γ→α转变,CGHAZ的组织为α铁素体及LM的混合组织,随着冷速的降低,α铁素体含量增加;当ωc=0.04℃/s时,CGHAZ的组织已完全转变为α铁素体和碳化物的混合组织。
By means of the physical simulation, the coarse grained zone in heat affected zone （CGHAZ） of CLAM steel during cooling process in the welding thermal cycles was conducted by using of the GleeblelS00 simulator. The effects of cooling rates on mierostructure transformation and Vickers hardness were investigated through microscopic observations, hardness tests as well as thermodynamic calculation with Thermo-calc software, and the SH-CCT diagram of the CGHAZ for CLAM steel was finally established. The results showed that the SH-CCT diagram exhibited only two transformation regions, i.e. low-temperature lath martensite （LM） region and high-temperature pro- eutectic ferrite （a-ferrite） region. 0.25~C/s was the critical cooling rate for phase transformation from supercooled austenite to full martensite. When the o^c ~0.25~C/s, the microstructure appearances of CGHAZ had no significant changes and consists of lath martensite and a small amount of ferrite within this range, the occurrence of 8 ferrite was attributed to incomplete transformation in the high temperature stage. When the the CGHAZ showed dual phase of a-ferrite and lath martensite because of the transformation. The content of ferrite increased with the decreased cooling rate. When the , the microstructure of CGHAZ was completely transformed to a-ferrite and carbides.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2013年第4期68-73,共6页
Journal of Materials Engineering
基金
国家重点基础研究发展规划资助项目(2008CB717802)
关键词
中国低活化马氏体钢
焊接热模拟
热影响区
连续冷却转变曲线
China low activation martensitic steel~ welding thermal simulation heat-affected zone con-tinuous cooling transformation curve
