使用状态对Q690CFD焊接接头性能的影响

Effect of different application state on properties of Q690CFD welded joint

针对煤矿机械、港口机械等对低成本焊接结构用高强钢的需求,宝钢开发了低成本TMCP高强钢Q690CFD,具有优异的综合力学性能和抗冷裂纹性能。对于高强钢厚板而言,焊后热处理工艺非常关键,它对接头的力学和使用性能有重要影响。在制造过程中,根据用户不同的服役条件,焊接结构要求不同的使用状态,比如焊态、消氢处理态和消应力处理态。按照相关的国家标准,采用实芯焊丝BH700-II,制作了Q690CFD的富氩气保焊接头,分析接头的不同使用状态,包括焊态、300℃消氢处理和580℃消应力处理对Q690CFD/BH700-II接头性能的影响。结果表明,焊态、消氢处理态和消应力处理态下,接头的力学性能均满足相关国家标准;按接头性能优劣来分,从好到差的顺序为:消氢处理态、焊态、消应力处理态。消氢处理可以一定程度上增加接头的冲击性能,但消应力处理使接头的冲击性能变差。

According to the demand of economical high strength structure steel mine machine and port machine, Baosteel developed a low-cost TMCP high strength proposed by coal steel Q690CFD, which has good weldability and comprehensive mechanical properties. Post-weld heat treatment is a key process and necessary for high strength heavy plate, and it has an important influence on welded joints＇ properties. In the process of steel structure manufaction, different application states are selected according to customer service situation, such as as-welded state, dehydrogenation state, stress relieved state. The effects of three states on mechanical properties of Q690CFD/BH700-II welded joint have been investigated according to related national standards. Three application states are as-welded state, dehydrogenation at 300 ℃ and stress relieving heat treatment at 580 ℃. The results show that the welded joints＇ mechanical properties can meet related national standards in three application states. The order from best to good is dehydrogenation at 300 ℃, as-welded state and stress relieving heat treatment at 580 ℃ in terms of Q690CFD/BH700-II welded joints＇ comprehensive mechanical properties. Dehydrogenation can improve the toughness of welded joint, whereas stress relieving heat treatment is harmful to the toughness of welded joint.