Dissimilar vacuum brazing of WC-Co and cold work steel utilizing a new near-eutectic silver-copper filler alloy

Abstract

Tungsten carbides are extremely high in hardness and they are wear-resistant materials. However, they are extremely brittle materials that render them ideal for many applications. Brazing technology has been proved to be a promising approach for joining tungsten carbide to tough metals to create high strength, tough and impact-resistant joint in the final assembly. In this research work, a dissimilar brazing of tungsten carbide (WC-Co) and cold work steel will be achieved using a new type of filler, a silver-copper near-eutectic alloy (BAg-8T) (Ag70Cu28Ti2). (BAg-8T) as a mixed alloy (eutectic and titanium) can melt/solidify completely in a very narrow temperature range (778 °C/800 °C), lower than any other existing brazing filler alloy; this will reduce the possibility of partial fastening while solidification. In addition, (BAg-8T) filler will act as the soft-iron gauze. Being soft and ductile metals, they will creep and absorb the movement due to differential contraction of the carbide and tool shank. Besides, they will improve the wetting on the carbide. In this research work, the effect of the joining parameters (brazing temperature and cobalt percentage in the tungsten carbide) on the mechanical properties and microstructure of the brazed joint will be investigated to determine the best joint performance.

Joining of cemented carbides WC–Co and tool steel X153CrMoV12 with capacitor discharge welding process

“…Ma et al [1] or Maizza et al [2] made an extensive study of possible joining methods. More or less successful methods used by various authors to join sintered carbides and steel include, in particular, laser beam welding with [3] [4] or without interlayer [5], electron beam welding [6], tungsten inert gas (TIG) welding [7], laser-TIG [8], diffusion welding [9], friction stir welding (FSW) [10] [11], vacuum brazing [12], high-frequency induction [13]. However, each of these techniques can lead to manufacturing defects that generally accumulate in the weld area, such as pores, cracks, delaminations, unbonded areas, phase embrittlement, residual stresses, and even peeling.…”