Ti-6Al-4V钛合金板与304L不锈钢网的扩散焊

分别在800℃、825℃、850℃焊接温度、30 m in保温时间,3 MPa焊接压力下,进行Ti-6A l-4V钛合金板与304L不锈钢网的真空扩散焊接。对接头组织结构与化学元素扩散进行了扫描电镜与能谱分析,并测试了接头的剪切强度。结果表明:不添加中间过渡层金属,可以成功地实现钛合金板与不锈钢网的扩散焊接,并使接头的剪切强度达到90 MPa以上。不锈钢网中的Fe、N、iCr扩散并固溶到钛合金中,稳定了β相,使钛合金在一定深度上,其组织由原来的α+β双相结构转变为单相的β相。不锈钢中的Cr,由于钛合金中Ti的扩散进入,而在界面发生了上坡扩散现象。这种Cr在不锈钢一定深度内的富集,形成窄长的富Cr区域,冷却后转变为硬脆的σ相。但在焊接接头中没有发现明显其它的金属间化合物或氧化物相的生成,使得接头的机械性能得到了很好的保证。

Diffusion Bonding of Ti-6Al-4V Plate and 304L Wiremesh

Diffusion bonding in vacuum was carried out between Ti-6Al-4V titanium alloy plate and 304L stainless steel wiremesh at the temperature range of 800 ℃,825 ℃ and 850 ℃ for 30 minutes under uniaxial pressure of 3 MPa.The microstructure of a diffusion zone was analysed by a scanning electron microscopy(SEM) and the interdiffusion of the sample across the interface was evaluated by electron probe microanalysis(EPMA) unit.The shear strength of the joint was tested,which reaches more than 90 MPa at the temperature range of 825 ℃~850 ℃.Elements of Fe,Ni and Cr coming from 304L steel wiremesh diffuse into Ti-6Al-4V,which stabilizes the β-phase mainly preserved after cooling down so that the microstructure of titanium alloy turns into a single β-phase from an original α+β double-phases structure at a certain depth.Uphill diffusion happens to its Cr at the interface of 304L steel because of the presence of Ti that has diffused from Ti-6Al-4V steel,which results in a narrow Cr enrichment zone.The zone turns into hard and brittle σ-phase cooling down.However,other intermetallics and oxides are not present apparently at the welded joint,which fairly ensures its mechanical performance.