TiAl合金与异种材料的摩擦焊接

Friction welding of TiAl alloy and dissimilar materials

摘要:

TiAl合金与42CrMo直接摩擦焊接性较差,为此分别引入高温合金GH3039、K418、N80A和纯镍N6作为中间材料,对TiAl—GH3039/K418/N80A/N6异种材料摩擦焊接工艺进行了研究。采用硬度计、扫描电镜和万能试验机对焊后接头区域的硬度、组织和焊合区成分变化以及接头机械性能等进行了分析。研究表明,TiAl合金与异种材料焊后接头中形成了复杂的多层状金属间化合物；TiAl与GH3039、N80A的摩擦焊接性较好,与K418、N6的摩擦焊接性较差；根据不同材料的线胀系数等随温度的变化规律,与TiAl合金焊接接头的抗拉强度,以及与42CrMo的摩擦焊接性,最终选择GH3039作为中间材料。通过引入中间材料,得到了TiAl涡轮+ 42CrMo转轴的异种材料整体转子,使得TiAl在涡轮增压器领域的应用成为可能。

Abstract:

The direct friction weldability of TiAl alloy and 42CrMo is poor, so the friction welding process of TiAl and GH3039/K418/N80A/N6 dissimilar materials was studied by introducing superalloy GH3039, K418, N80A and N6 as intermediate materials. The hardness, microstructure, composition and mechanical properties of welded joint were analyzed by hardometer, scanning electron microscope and universal tester. Studies had shown that complex intermetallic compound layers were formed at the weld interface of TiAl alloy and dissimilar materials; Additionally, the friction weldabilities of TiAl with GH3039 and N80A are better than that with K418 and N6; GH3039 is selected as the intermediate material to improve the friction weldability of TiAl alloy and 42CrMo dissimilar material based on a) the linear expansion coefficient that varies with temperature, b) the tensile strength of the welded joints with TiAl, and c) the friction weldability with structural steel 42CrMo. By introducing the intermediate material, the integral rotors of TiAl turbine + 42CrMo shaft are obtained, which represents a practical application of TiAl alloy in the field of the turbocharger.