LC52厚板搅拌摩擦焊组织性能分析

Microstructure and Properties in Friction-stir Welds of LC52 Slab

采用搅拌摩擦焊方法对厚度为15mm的LC52铝合金板进行了单道焊接试验,并对焊缝的微观组织与力学性能进行了分析。试验结果表明,在旋转速度为1500r/min,且焊接速度为60mm/min时,可以获得较好的焊缝组织,其抗拉强度达到了338MPa。焊核区内是细小均匀的等轴晶,平均晶粒大小在4μm左右。焊缝两侧热机影响区的组织存在较大差异,前进侧热机影响区为塑性变形角较小的窄条形组织,后退侧热机影响区为塑性变形角较大的扁平块状组织。热影响区的组织发生了粗化。焊缝中的部分强化相η′相因过时效转变为η相是焊缝强度低于基材强度的主要原因。

Friction-stlr welds of LC-52 alloy in 15 mm thickness were completed in a single pass. The results demonstrate that the good weld can be achieved when the rotating speed is 1500r/min and the welding speed is 60mm/min, and its tensile strength can reach 338MPa. The weld nugget zone consists of fine equiaxed grains, which sizes are about 4μm. The thermo-mechanically affected zones on the weld＇s beth sides are very different, that on the advancing side consists of narrow and strip grains which distortion angles are small, while that on the retreating side consists of flat and nubby grains which distortion angles are big. The heat affected zone consists of grown grains. Because some η＇ precipitations are transferred to ηphases for over-aglng, the tensile strength of the weld is lower than that of the base metal.