辊压预应变对焊接接头组织性能的影响

采用辊压加载的方法在焊接接头处形成微量的塑性预应变,研究辊压变形后材料本身的疲劳性能和力学性能变化(不计表面效应)。利用 SEM 观察疲劳断口和 TEM 观察位错形貌。试验结果表明,虽然金属辊压变形后的强度和硬度有所提高,但疲劳极限明显降低,断口呈完全的脆性状态,位错大量增殖并表现为胞状亚结构。可以认为,辊压后材料中位错的特殊结构和材料内部所形成的损伤累积是疲劳性能下降的主要原因。

Effect of Rolling Prestrain on Microstructure and Property of Welded Joints

After rolling deformation,the fatigue and mechanical properties of the welded joints were studied(neglecting surface effect).The fractograph and dislocation were observed with SEM and TEM.The experimental result ind- icated that the fatigue limits of the matetial rolled is significantly decrea- sed althrough its strength and hardness are apparently,increased.A brittle fractograph is fond on the fatigue sample.It is considered that special disl- ocation structure and inner damage formed in the welded joint by rolling is the main reason for the decrease of fatigue strength.