Q345R钢厚板焊接接头断裂疲劳性能试验研究

对60mm厚度的Q345R钢手工焊焊接接头的金相组织、断裂性能和疲劳性能进行了试验研究,讨论了厚板焊接接头在母材、焊缝和热影响区的断裂韧度JIC和不同深度下的疲劳裂纹扩展速率变化情况。结果表明:①Q345R钢厚板焊接接头焊缝区组织为细化均匀的铁素体和少量珠光体,热影响区和母材组织均为粗大铁素体和少量珠光体。②焊缝的断裂韧度(309.35kJ/m2)较母材(227.97kJ/m2)和热影响区(237.26kJ/m2)好,热影响区和母材断裂韧度接近。③在相同应力强度因子幅下,焊缝区材料的疲劳裂纹扩展速率低于母材,坡口中间层疲劳裂纹扩展最慢。④热影响区不同深度试样的疲劳裂纹扩展速率一致,比母材稍慢。⑤应力比对热影响区疲劳裂纹扩展速率没有影响,但对焊缝区试样有一定影响,当应力强度因子幅小于30MPa槡m时,应力比大,裂纹扩展速率快。

Experimental Study in Fracture and Fatigue Property of Weld Jointing with Thick Q345R Steel Plan

Weld jointing of Q345R＊steel with thickness of 60 mm was investigated in experiment. The fracture toughness of weld, heat-affected zone and base metal was tested respectively. The fatigue crack growth rate of the specimens from different depth in thick direction was conducted in weld and heat-affected zone. The results revealed that the weld zone was composed of fine fer- rite and little pearlite, while the heat-affected zone and base metal consist of coarse ferrite and lit- tle pearlite. The fracture toughness of weld （309.35 kJ/mz） was better than that of the heat-af- fected zone （237.26 kJ/mz） and base metal （227. 97 M/me）. Similarly, at a given stress intensity factor range, the fatigue crack growth rate of the weld was slower than that of the heat-affected zone and the base metal. There is the slowest fatigue crack growth rate from the specimen lied in the middle of welding groove in thick direction. The fatigue crack growth rate of the specimens from heat-affected zone was close and a little slower than that of the base metal. The effect of load ratio was not discovered in the specimens from the heat-affected zone. While the fatigue crack growth rate increases with the increasing of load ratio in the specimens from the weld zone when the stress intensity factor range is lower than 30 MPa √m.