北京工人体育场高强度厚板钢低温焊接仿真与试验研究

39,82.Simulation and experimental study on low temperature welding of high strength thick plate steel in Beijing Workers Stadium

针对北京工人体育场改造复建冬季现场低温环境下高强厚板复杂钢结构焊接作业难度大的问题,开展了-15℃低温环境Q460GJC厚板焊接接头温度场、显微组织、力学性能模拟和工艺试验研究。结果表明:预热温度为170℃时,焊接开始时,V形坡口斜面端温度比直端低,实测温度前三层焊接后温度比预热温度低,第6层焊接后温度趋于一致,略高于预热温度,实际温度比模拟温度略低20℃左右,均小于225℃的要求值;模拟焊接后,焊缝处的组织主要由铁素体、珠光体和贝氏体组成,铁素体占50%左右;通过显微组织观察,焊缝区主要是铁素体与珠光体,表层区主要是铁素体与球状珠光体,中心层区出现了板条状珠光体,热影响区组织为铁素体+贝氏体;显微硬度范围188~275HV,焊缝极限强度值在640MPa左右;通过对比模拟结果与实测结果,基于焊接热模拟及焊接冶金基础理论可有效实现高强钢厚板焊接组织性能预测分析。

In order to solve the problem of difficult welding operation of complex steel structure of high strength thick plate under low temperature environment in the reconstruction of Beijing Workers Stadium in winter,the temperature field,microstructure,mechanical properties simulation and process test of welded joint of Q460GJC thick plate in-15℃ low temperature environment were carried out.Results show that when the preheating temperature is 170℃,the temperature of V groove welding bevel end is lower than the straight side at the beginning.The measured temperature of the first three layer after welding is lower than the preheating temperature while the temperature after the sixth layer tends to be same and is slightly higher than the preheating temperature.The actual temperature are all lower than the required value of 225℃ and about 20℃ lower than the simulated temperature.After simulated welding,the microstructure of the weld joint is mainly composed of ferrite,pearlite and bainite,with ferrite accounting for about 50%.According to the microstructure observation,the microstructure of weld zone is mainly ferrite and pearlite,the surface zone is mainly ferrite and spherical pearlite,the central layer of the plate is lamellar pearlite,the heat affected zone is ferrite+bainite.The microhardness range is 188~275HV,and the ultimate strength of the weld joint is about 640MPa.By comparing the the measured results with simulation results,the prediction analysis of welding microstructure and properties of high strength thick steel plate can be effectively realized based on welding thermal simulation and basic theory of welding metallurgy.