不同冷速下Q1100高强钢焊接热影响区粗晶区的组织转变特征
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摘要
利用Gleeble-3500型热模拟试验机对Q1100高强钢的焊接过程进行模拟,采用热膨胀法结合显微组织与硬度测试,绘制了该钢的模拟热影响区连续冷却转变曲线(SHCCT曲线),研究了不同冷却速率下焊接热影响区粗晶区的组织转变特征和硬度变化规律。结果表明:在模拟焊接条件下,该钢的奥氏体化温度明显高于平衡状态下的奥氏体化温度;当冷却速率低于2℃·s~(-1)时,热影响区粗晶区为全贝氏体组织;当冷却速率为2~12℃·s~(-1)时,热影响区粗晶区为贝氏体和马氏体的混合组织;当冷却速率超过12℃·s~(-1)时,热影响区粗晶区得到全马氏体组织;随着冷却速率增加,焊接热影响区粗晶区的硬度逐渐增大。
The welding process of Q1100 high-strength steel was simulated with Gleeble-3500 thermal simulator,and then SHCCT(simulated HAZ continuous cooling transformation)diagram of the steel was obtained by using thermal expansion measurement combined with microstructure analysis and hardness testing.The microstructure transformation characteristics and hardness change rule of coarse-grained heat-affected zone(CGHAZ)were studied at different cooling rates.The results show that,the austenitizing temperature of the steel in simulated welding condition was significantly higher than that in the equilibrium state.The CGHAZ was full bainite when the cooling rate was under 2 ℃·s~(-1),a mixed microstructure of bainite and martensite was obtained when the cooling rate was 2-12℃·s~(-1),and the CGHAZ was full martensite when the cooling rate was over 12 ℃·s~(-1).The hardness of CGHAZ increased gradually with the increase of cooling rate.
The welding process of Q1100 high-strength steel was simulated with Gleeble-3500 thermal simulator,and then SHCCT(simulated HAZ continuous cooling transformation)diagram of the steel was obtained by using thermal expansion measurement combined with microstructure analysis and hardness testing.The microstructure transformation characteristics and hardness change rule of coarse-grained heat-affected zone(CGHAZ)were studied at different cooling rates.The results show that,the austenitizing temperature of the steel in simulated welding condition was significantly higher than that in the equilibrium state.The CGHAZ was full bainite when the cooling rate was under 2 ℃·s~(-1),a mixed microstructure of bainite and martensite was obtained when the cooling rate was 2-12℃·s~(-1),and the CGHAZ was full martensite when the cooling rate was over 12 ℃·s~(-1).The hardness of CGHAZ increased gradually with the increase of cooling rate.
引文
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[2]WANG X,DI H,ZHANG C,et al.Weldability of 780 MPa super-high strength heavy-duty truck crossbeam steel[J].Journal of Iron and Steel Research(International),2012,19(6):64-69.
[3]张元杰,彭云,马成勇,等.Q890高强钢焊接淬硬倾向和冷裂纹敏感性[J].焊接学报,2013,34(6):53-56.
[4]BERG J,STRANGHOENER N.Fatigue strength of welded ultra high strength steels improved by high frequency hammer peening[J].Procedia Materials Science,2014,3:71-76.
[5]高有进,王乘,徐宗林.屈服强度900MPa级高强钢焊接工艺[J].焊接学报,2007,28(9):103-107.
[6]裘尧健,曹凤豫,杨让.合金元素对中碳硅锰钼钒钢连续冷却转变及淬透性的影响[J].工程科学学报,1983(1):105-121.