Achieving superior low temperature and high strain rate superplasticity in submerged friction stir welded Ti-6Al-4V alloy
Achieving superior low temperature and high strain rate superplasticity in submerged friction stir welded Ti-6Al-4V alloy
复制标题
在埋入式搅拌摩擦焊 Ti-6Al-4V 合金中实现优异的低温和高应变率超塑性
DOI：
10.1007/s40843-017-9145-4
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发表时间：
2018
影响因子：
8.1
通讯作者：
Ma Zongyi
中科院分区：
文献类型：
--
作者：
Wu Lihui;Zhang Hao;Zeng Xianghao;Xue Peng;Xiao Bolv;Ma Zongyi
钛合金焊缝超塑成形在制造集成部件方面具有巨大的应用前景。然而，无论是熔焊还是常规搅拌摩擦焊（FSW），钛合金焊缝的焊核区（NZ）均为片状组织，表现出低的超塑性或高的超塑性温度和低的应变速率。结果表明，NZ对整个焊缝的超塑性成形起着主要的阻碍作用。首次对Ti-6Al-4V合金进行了搅拌摩擦焊，获得了无缺陷的焊缝，焊缝区为带状组织。NZ在600 ℃时表现出低温超塑性，这是钛合金焊缝中有报道的最低超塑性温度。此外，在800 ℃时，NZ表现出高应变速率（3× 10− 2 s− 1）的超塑性，在1× 10− 3 s− 1时的最大延伸率为615%。与常规搅拌摩擦焊接头相比，SFSW接头NZ区的流变应力明显降低，最佳超塑性温度降低了100 ℃。这主要是由于薄带组织易于球化，增强了晶界/相界滑动的能力。
The superplastic forming of Ti alloy welds has great application prospects in producing integrated components. However, the nugget zone (NZ) of the Ti alloy welds, produced by fusion welding or conventional friction stir welding (FSW), consists of lamellar microstructure, which exhibits either low superplasticity or high superplastic temperautre and low strain rate. As a result, the NZ plays a leading role in hindering the superplastic forming of the whole welds. In this study, submerged friction stir welding (SFSW) was conducted in Ti-6Al-4V alloy for the first time, and a defectfree weld with the NZ consisting of a strip microstructure was obtained. The NZ exhibited a low-temperature superplasticity at 600 C, which was the lowest superplastic temperature ever reported in the Ti alloy welds. Besides, at 800 C, the NZ showed high strain rate (3× 10− 2 s− 1) superplasticity and a largest elongation of 615% at 1× 10− 3 s− 1. Compared to conventional FSW joints, the NZ of SFSW joint exhibited a much lower flow stress and a decrease in optimal superplastic temperature by 100 C. This is mainly attributed to the easy globularization of the strip microstructure, enhancing the ability of grain/phase boundary sliding.