热等静压对Inconel 690镍基合金堆焊层组织与耐磨性能的影响

Effect of HIP Process on Microstructure and Wear Resistance of Inconel 690 Ni-based Alloy Surfacing Layer

使用自动化TIG焊方法在347不锈钢表面堆焊了Inconel 690镍基合金。采用热等静压(HIP)工艺在1120℃对Inconel 690镍基合金堆焊层进行了消除缺陷处理,并对HIP前后的堆焊层组织与耐磨性能进行了研究。结果表明:Inconel 690合金堆焊层经过HIP处理后,可消除其内部缺陷和组织偏析,同时靠近熔合线界面的堆焊层区域组织由柱状树枝晶转变为粗大的奥氏体,原始焊缝层与层之间的界面也被消除。HIP处理后,堆焊层的硬度明显下降。这是由于堆焊层内部晶粒取向发生变化,位错产生了运动,缠结的位错重新组合,导致位错密度下降,同时,堆焊层内部的焊接残余应力也得到了释放。HIP处理后,堆焊层耐磨性变差,磨损机制主要为磨粒磨损和黏着磨损。

Inconel 690 Ni-based alloy was deposited on the surface of 347 stainless steel by using the method of automatic TIG welding. The hot isostatic pressing （HIP） at 1120 ℃ was used to eliminate the defects oflnconel 690 Ni-based surfacing layer, and the microstructure and wear resistance of the surfacing layer before and after HIP process were analyzed. The results show that the internal defects and segregation of Inconel 690 alloy surfacing layer can be eliminated after HIP. The microstructure of the surfacing layer near the fusion line is changed from columnar dendrite to coarse austenite, and the interface between the original weld layers is also eliminated. After HIP, the hardness of the surfacing layer decreases obviously. This is due to that the change of grain orientation in the surfacing layer, the movement of dislocations and the recombination of tangled dislocations lead to the decrease of dislocation density and the release of welding residual stress in the surfacing layer. After HIP, the wear resistance of the surfacing layer becomes worse. The wear mechanisms are abrasive wear and adhesive wear.