基于搅拌摩擦点加工技术的TA15钛合金板及其TIG焊接接头组织及硬度

摘要

Effects of friction stir spot processing (FSSP) on the microstructures and microhardness of tungsten inert gas (TIG) welded TA15 titanium alloy joints were investigated. The macro/micro structural observation and microhardness evaluation of the TA15 alloy sheets and TA15 TIG welded joints were carried out using optical microscope and microhardness tests. The results show that FSSP effectively improves the microstructure and increases the microhardness of the TA15 sheets. As for the TIG welded joints, FSSP also effectively improves the microstructure of joints. And the average microhardness value in weld nugget zone is improved significantly, while a small increase of this value in heat affected zone is observed. The hardness in stirring zone is significantly higher than that in the base metal. Two peak values of hardness appear along the width direction in stirring zone. After FSSP, the average hardness of the weld zone of TA15 TIG welded joint is significantly higher than that before FSSP. Under the present process parameters, both the surface oxidation in TA15 sheets and in TIG welded joints after FSSP are not evident, while the surface forms the bright white layer, which is composed of a great multitude of fine grains.%基于搅拌摩擦点焊加工技术(FSSP),对TA15钛合金TIG焊接接头的组织和硬度进行研究.采用金相分析和硬度测试方法,分别对TA15板材及其TIG焊接接头进行组织分析和硬度测试.结果表明,FSSP不但能有效改善TA15板材组织,而且可以提高其显微硬度,同时也可以改善TA15合金TIG焊接接头的显微微组织.焊核区平均显微硬度值显著提高,热影响区显微硬度值略有增加.搅拌区的硬度明显高于母材,且沿着宽度方向出现两个硬度峰值.经过FSSP之后,TA15合金TIG焊接接头焊核区的平均硬度值与FSSP之前相比,有了显著提高.此外,在所选工艺参数下,TA15板材及其TIG焊接接头经过FSSP之后,表面氧化均不明显,同时也发现,表面均出现晶粒细小的光亮白层组织.