高频机械冲击处理的焊接接头疲劳强度评定

目的研究结构应力法和缺口应力法评估经高频机械冲击处理的高强度钢焊接接头疲劳强度。方法在名义应力法相关的研究基础上,采用结构应力法和缺口应力法,分析四种常见焊接接头经高频机械冲击焊后处理的疲劳测试数据,通过统计分析得出各评估应力系统下合适的特征强度FAT值。将统计结果分别与各种焊接接头的疲劳测试数据对比,分析其FAT值的适用性。结果分别在结构应力系统和缺口应力系统下导出了特征疲劳强度推荐FAT值。它们采用随材料屈服强度变化的FAT等级和m=5的S-N斜率指数,且与各种接头的疲劳数据符合较好。结论经高频机械冲击处理后,钢材的焊接接头疲劳强度对材料屈服强度有明显的统计差异,需要采用随材料屈服强度变化的FAT等级。采用文中分析得出的结果,可以在不失安全的情况下,充分利用高强度钢材经高频机械冲击焊后处理的优异特性。

Fatigue Assessment of Welded Joints Treated by High Frequency Mechanical Impact

The work aims to study the fatigue assessment of the welded joints made of high strength steel and treated by high frequency mechanical impact (HFMI) with the structural stress approach and notch stress approach. Based on the research for the nominal stress approach, the HFMI treated test data from four types of welded joint were analyzed by the structural stress approach and notch stress approach. Then the characteristic FAT values for the relevant stress system were statistically proposed. The applicability of proposed FAT values was checked by comparing the values with the relative test data series of welded joints. The characteristic FAT values for the structural stress system and notch stress system was proposed. S-N curve of FAT classes and m=5 varying with the material strength was adopted. The proposed FAT values were in good agreement with the fatigue data for every type of welded joint. For the welded joints treated by HFMI, their fatigue strengths are statistically varying with the material strength. Thus a characteristic FAT value varying along with the material strength should be taken. The excellent properties of high strength steel treated by high frequency mechanical impact can be used fully by the analysis re sults without reducing the safety.