硬质合金与钢焊接的研究进展

Research Progress of Welding Between Cemented Carbide and Steel

硬质合金与钢的连接可以实现高硬度、高强韧的理想结合,从而极大地拓展硬质合金的应用领域和应用范围。常用的连接方法主要有机械固定和焊接等方法,其中焊接方法因具有连接强度高、稳定性好和服役寿命长等优点被广泛应用。焊接中基于热源类型形成了多种焊接技术,各种焊接技术可获得相应的接头组织和性能以适用于不同要求。本文系统地介绍了当前国内外关于硬质合金与钢焊接的最新研究进展,包括钎焊、扩散焊、电弧焊、高能束焊、复合热源焊、摩擦焊以及电阻焊,对比了这些焊接方法及其焊接工艺对接头力学性能和微观组织的影响。其中,钎焊属于非熔焊接,因具有工艺简单、成本低廉的特点被广泛应用,目前的研究着重于开发各种新型钎料以改善其润湿性,从而提高焊接接头强度;而电弧焊、高能束焊、复合热源焊等熔焊可在焊接界面处产生良好的冶金结合,实现较高强度的连接。然而,熔化焊在界面处不可避免地产生了具有典型特征的η相,由于其脆性而恶化了接头性能。因此,本文综述了各种焊接方法对η相的生成原因及抑制机制,着重介绍了电阻点焊中η相的形核机理和长大模型,最后对未来硬质合金与钢焊接的研究重点和发展方向进行了展望。

The connection between cemented carbide and steel can realize the ideal combination of high hardness and high strength and toughness,thus greatly expanding the application field and application range of cemented carbide. The commonly used connection methods mainly include mechanical fixation and welding,among which the welding method is widely used because of its high connection strength,good stability and long service life. A variety of welding technologies are developed based on the type of heat source in welding,each of which can obtain the corresponding joint microstructure and properties to meet different requirements.This paper systematically introduces the latest global research progress on the welding of cemented carbide to steel,including brazing,diffusion welding,arc welding,high energy beam welding,hybrid heat source welding,friction welding and resistance welding. The effects of these welding methods and welding processes on the mechanical properties and microstructure of joints are compared. Among them,brazing is a kind of non-fusion welding and has found wide application because of its simple process and low cost. At present,the main research of brazing focuses on the development of various new solders to improve their wettability,so as to improve the strength of welded joints. Arc welding,high energy beam welding,hybrid heat source welding and other fusion welding can produce good metallurgical bonding at the welding interface and achieve high strength connection,yet almost inevitably induce the generation of typical η phase at the interface of fusion welding,which deteriorates the properties of the joint because of its brittleness. Therefore,this paper summarized the research reports on the formation and inhibition of η phase in various welding methods and welding processes,with emphasis on the nucleation mechanism and growth model of η phase in resistance spot welding. Finally,the future research focus and development direction of welding cemented carbide and steel are prospected as well.