焊接接头在预应变下断裂性能试验研究

Experimental Research on the Fracture Performance of Welded Joints under Pre-strain

以常用建筑结构钢Q345为研究对象, 进行了母材与焊缝在预应变下的冲击、拉伸和断裂韧度试验。结果表明,预应变下,母材和焊缝的冲击韧度均有所降低,韧-脆转变温度有所提高,10%预应变后的焊缝其韧-脆转变温度低于室温(20℃),仍可在室温下安全使用,随预应变增加,材料的屈服强度与抗拉强度均有所提高,脆性断裂危险性增加。研究发现,为建立客观的材料韧度指标及进行更有效的安全分析时,预应变应作为一个考虑因素。

The Charpy notch impact, tension and fracture toughness tests on structural steel Q345 were carried out under different pre-strains. The results show that: the impact toughness of both base metal and weld metal decreases and the ductile-brittle transition temperature increases a little under pre-strain. The range of ductile-brittle transition temperature of the weld metal under 10% pre-strain is lower than the room temperature (20°C), at which it can be used safely. At the same time, both the yield strength and tensile strength increase and the brittle fracture is in high potential under pre-strain. From the researches in this paper, the conclusions can be drawn that the pre-straining effect should be considered when establishing objective toughness standard and carrying out more effective safety analysis.