沪通长江大桥钢结构接头热影响区硬度影响因素分析

Analysis of Hardness Influential Factors for Steel Structure Joint Heat Influential Zone of Hutong Changjiang River Bridge

沪通长江大桥钢桁梁主要采用Q370qE和Q420qE钢板,在焊接工艺评定试验中发现部分Q370qE钢接头热影响区硬度超标(硬度值>380HV10)。针对此情况,采用不同的接头形式、焊接方法、焊接材料进行多组焊接对比试验,研究不同焊接工艺及钢板化学成分对钢结构接头热影响区硬度的影响。研究结果表明:钢板的材质与接头热影响区硬度超标有较大的相关性;控制焊接热输入及焊道层间预热温度,并尽量采用多层多道焊的焊接方式,能够有效控制接头热影响区硬度超标问题;钢板中的碳元素含量及合金元素配比对接头热影响区硬度有影响,应严格控制碳元素含量,优化合金元素配比。

The steel truss girder of Hutong Changjiang River Bridge is made of Q370qE and Q420qE steel plates.In the welding technique evaluation tests,the hardness of the heat influential zone of the Q370qE steel joints was found exceeding the standard value(hardness value>380 HV10).In view of this condition,different joint types,welding methods and welding materials were taken to carry out multiple groups of welding comparison tests,to study the influence of different welding technique and chemical composition of steel plate on the hardness of the heat influential zones of the steel structure joints.The results show that the material of the steel plate has great correlation with the excessive hardness of the heat influential zone of the joint.The excessive hardness problem of the heat influential zone of the joints can be effectively controlled by controlling the welding heat influx and the preheating temperatures in the layers of welding beads and using the multilayer and multiple welding beads method.In addition,the content of carbon and the mixing proportion of alloying elements have influence on the hardness of heat influential zone of joints,and it is better to rigorously control the content of the carbon and optimize the mixing proportion of the alloying elements.