高强度钢材对接焊缝低温冲击韧性试验研究

Experimental study on mechanical properties of butt weld of Q690 high strength steel

对Q460D和Q690D高强度钢材对接焊缝进行低温冲击试验,得到低强和等强两种匹配下,焊缝区、热影响区的冲击功值,讨论了两种匹配形式下冲击功值AKV随温度的变化规律。结果表明:焊缝区和热影响区随温度降低韧性逐渐变差,热影响区的AKV总是大于焊缝区,表明经过焊接热循环后,热影响区的冲击韧性处于较高的水平;采用低匹配连接,焊缝区和热影响区的冲击功均大于等匹配,说明低匹配可获得良好的吸收能量的能力。同时,利用Boltzmann函数对试验结果进行拟合分析,将高强度钢材两种匹配下焊缝区和热影响区的韧性进行了对比。由试验数据比较可知,焊缝区吸收能量的能力较差,为主要断裂部位。

In order to investigate the mechanical properties of Q690 D steel butt weld under different matching forms, the static tensile and low temperature impact tests are carried out. The results show that under the under matching and equal-matching forms, deformation capacity and bearing capacity of Q345 B and Q690 D steel butt weld connection are relatively close, and the fracture position is mainly at the base metal, which indicates that the under matching form is more reasonable. As for the same steel butt weld of Q690 D, the ultimate load under the equal-matching form is improved about 13% than under the under matching form, lower than the parent metal, and the deformation capacity is poor, which should be noted in the actual projects. With the under matching connection, impact energy of weld zone and HAZ is greater than that in equal-matching connection, which explains that under matching connection can gain a better ability to absorb energy. At the same time, a regression analysis of the influences of different temperatures on impact energy are made using Boltzmann function, and the ductile-brittle transition temperatures in Q690 steel weld zone and HAZ are obtained.