摘要
A detailed investigation for the influence of post weld heat treatment （PWHT） on the microstructure of TC4 and TC17 dissimilar joints was analyzed. The fully transformed microstructure in the as-welded zone indicated that the peak temperature exceeded theβ-transus temperature at the weld interface during linear friction welding. TC4 side was mainly composed of martensiteα′phase with random distribution and it was singleβfor that of TC17. In the thermomechanically affected zones of TC4 and TC17, the structure undergoes severe plastic deformation and re-orientation, yet without altering the phase fractions. After PWHT, in the weld zone of TC4 alloy, the phase transformationα′→α＋βoccurred and the acicularαwas coarsened, which resulted in a decrease in hardness. In the weld zone of TC17 alloy, fineαphase precipitated at the grain boundary and withinβgrains, which resulted in a sharp increase in hardness.
研究焊后热处理对TC4和TC17异质钛合金线性摩擦焊接头显微组织的影响。焊态条件下焊缝组织为完全再结晶组织,表明线性摩擦焊接过程中,摩擦界面温度超过β相变点温度,其中TC4侧焊缝组织主要为具有马氏体组织结构的α′相,TC17侧焊缝组织主要为单一的β相。TC4与TC17侧热力影响区组织为严重的变形组织,且具有明显的方向性,但在该区各相的体积分数未发生变化。热处理后,TC4侧焊缝组织中α′转变为针状的α+β相,且随着热处理温度的升高,针状α相粗化,长大现象明显,并导致该区的显微硬度下降。TC17侧焊缝组织热处理后从晶界和β晶粒内部析出了细小的α相,导致该区显微硬度明显提高。
