摘要
利用拉—拉疲劳法和金属磁记忆检测法研究了20CrMo钢焊缝在方波加载方式下疲劳裂纹扩展与自发射磁信号的相关性,用扫描电镜对疲劳断口特征进行了研究.结果表明,裂纹到达焊缝中心前,随着疲劳寿命的增加,焊缝处的自发射磁信号也随着增加,疲劳裂纹扩展速率先增加后减小,当裂纹越过焊缝后,随着疲劳寿命的增加,焊缝处的自发射磁信号开始减小,疲劳裂纹的扩展速率却迅速增加.在焊接接头的不同区域,疲劳裂纹扩展速率也不相同,其中热影响区扩展速度较快,而在其它区域扩展速率相对较慢.断口扫描分析表明方波加载方式下的疲劳断口为类解理断裂.
The relationship between fatigue crack growth and self-emission magnetic signal for 20CrMo steel weld seam at the square wave load was studied by tension-tension fatigue experiment and metal magnetic memory test method.The characteristics of fatigue fracture were studied by SEM.The results show that with the increase of fatigue cycles,the self-emission magnetic signal of the weld seam increased,the fatigue crack growth rate firstly increases and then decreases before the crack reaches the weld.When the crack across the weld seam,with the increase of fatigue cycles,the self-emission magnetic signal of the weld seam begins to decrease,but the fatigue crack growth rate incrases rapidly.In different zones of the welded joint,the fatigue crack growth rates are different,the expansion rate for the heat-affected zone is faster,while in other regions the expansion rate is relatively slower.The fracture scanning analysis reveals that cleavage fatigue fracture occurs under the condition of square wave loads.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2013年第12期55-58,3-4,共4页
Transactions of The China Welding Institution
基金
国家自然科学基金面上资助项目(51074133)
四川省高等学校油气田材料重点实验室资助项目(12YQT028)
关键词
方波加载
20CrMo钢焊缝
金属磁记忆
疲劳裂纹
square wave loads
20CrMo steel welding seams
metal magnetic memory
fatigue crack
