摘要
用Gleeble-3500型热模拟试验机模拟单道次焊接条件下FB780钢焊接接头热影响区(HAZ)的热循环过程,研究了在不同焊接峰值温度及不同t8/5(由800℃冷却到500℃的时间)下HAZ的显微组织,并测试了不同焊接条件下HAZ的显微硬度和冲击韧性。结果表明:在t8/5相同的条件下,随着峰值温度的升高,HAZ组织粗化;当峰值温度一定时,随着t8/5的增加,铁素体板条变宽并逐渐融合,M/A组元粗化,粗大铁素体晶粒与细小准多边形铁素体晶粒混合,组织的均匀性恶化;在相同的峰值温度条件下,HAZ的硬度和冲击功均随着t8/5的增加而降低;在峰值温度为1 175℃,t8/5为6s条件下,HAZ的低温(-20℃)冲击断口形貌为韧窝花样,韧窝尺寸较大,HAZ的低温韧性与母材的相匹配,同时硬度较高,该工艺为最佳的单道次焊接工艺。
The thermal cycle process of the heat affected zone(HAZ)of FB780 steel welded joint under single pass welding condition was simulated by the Gleeble-3500 thermomechanical simulator.The microstructures of HAZ at different welding peak temperatures and for different t8/5times(cooling time from 800 ℃ to 500 ℃)were studied,and the micro-hardness and impact toughness of HAZ under different welding conditions were tested.The results show that when the t8/5 was the same,the microstructure of HAZ coarsened with the increase of peak temperature.When the peak temperature was constant,with the increase of t8/5,the ferrite lath widened and gradually intergrated;the M/A component coarsened;the coarse ferrite grains were mixed with the fine quasipolygonal ferrite grains;the metallographic homogeneity deteriorated.At the same peak temperature,the hardness and impact energy of HAZ decreased with the increase of t8/5.At the peak temperature of 1 175℃and t8/5of 6s,the impact fracture morphology of HAZ at low temperature(-20℃)showed dimple pattern,and the dimple was relatively large;the toughness of HAZ at low temperature matched with that of the base metal;the hardness was relatively high;all indicated that the process was the best single pass welding process.
作者
朱浩
张梅
叶青亮
ZHU Hao;ZHANG Mei;YE Qingliang(SAIC Motor Passenger Vehicle Co.,Shanghai 201804,China;School of Materials Science and Engineering,Shanghai University,Shanghai 200072,China)
出处
《机械工程材料》
CAS
CSCD
北大核心
2019年第1期54-57,63,共5页
Materials For Mechanical Engineering
