等温变形对异种钛合金焊缝组织性能的影响

通过改变等温变形工艺参数探讨了焊缝显微组织的变化机理与焊件的室温拉伸性能。结果表明:在较低应变速率下,以较大变形量变形时,焊接界面晶粒细化与位错切过晶界和晶内的O/α2相条及O/α2发生拉长、颈缩而断开的机制有关,变形量小时则主要以位错切断晶界及晶内O/α2条为主。应变速率低(10-4s-1)和高(10-2s-1)时,出现的粗细不同条状O/α2相是与动态再结晶的响应速率有关。在980℃,以10-2～10-4s-1应变速率和30%～50%变形Ti2AlNb/TC11双合金焊接接头,可得到高于TC11合金的室温强度。

Influence of Isothermal Deformation Parameters on Microstructures and Properties of Welded Zone of Dissimilar Titanium Alloy

The evolution mechanism of the weld zone microstructure and the room temperature tensile strength of the weldment for Ti2AlNb/TC11 dissimilar alloy were investigated through changing the isothermal deformation parameters.Results show that at lower strain rate with higher deformation,the grain refinement of the welded interface is related to dislocation cutting across grain boundary and intragranlar strip O/α2-phase and elongated O/α2-phase necking down.With low deformation,the grain refinement is only related to dislocation cutting across the grain-boundaries and transgranular strip O/α2-phases.Appearance of course and fine strip O/α2-phases is related to response of dynamic recrystallization at low strain rate(10-4 s-1) and high strain rate(10-2 s-1).After hot deformation at 980 ℃,at strain rate of 10-2-10-4 s-1 and deformation of 30%-50%,the room-temperature strength of the Ti2AlNb/TC11 dual-alloy joint is better than that of TC11 alloy.