基于TIG电弧重熔的焊后复合处理工艺改善T形接头疲劳强度的研究

T joints fatigue strength improving by hybrid heat treatment process after tungsten inert-gas arc remelting

以制造转向架焊接构架常用的Q345钢T型MAG焊接头为对象,研究采用焊后复合处理新工艺,即在构架现行制造工艺流程中增加一道焊趾TIG电弧重熔工序对T形接头疲劳强度的改善作用。试验结果表明,与焊态下相比,现行制造工艺使接头的疲劳强度提高了29%,新工艺则提高了56%。文中从三个方面分析了新工艺明显改善T形接头疲劳强度的原因,即焊趾处应力集中系数下降、焊趾部位微观组织细化和焊趾表面状态改变。研究表明新工艺应用于铁路提速转向架生产中是可行的。

In view of MAG welded Q345 T joints used in bogies, TIG (tungsten inert-gas) arc was used to remelt weld toe. The results indicate that the remelting procedure improves the fatigue strength of T joints, which the fatigue strength increased by 56 percent. The reasons of remelting procedure which can improve the fatigue strength can be concluded to three points. Firstly it can reduce the weld toe stress concentration coefficient. Secondly it can refine the weld toe zone crystal. Lastly it can change the weld toe zone exterior. We can found that it' s feasible to use the remelting procedure.