Laser surface modification of a low carbon steel with tungsten carbide and carbon

Abstract

For many industrial applications it is sufficient to have a small area of wear resistant surface. For this reason, cheap low carbon steel is chosen for the partial laser surface alloying. Laser alloying experiments of low carbon steel (16MnCrS5) were carried out by powder injection (WC/Co 88/12) and with graphite precoating for comparison. In addition, melt injection of tungsten carbide was used to produce a composite layer with hard tungsten carbide particles embedded in tough metal matrix. Detailed material investigations (metallographical, electromicroscopical and EDX-analyses) were under-taken on the samples obtained with these methods.The experimental results indicate that for the samples alloyed with carbon, the hardness increases due to martensitic transformation. In the case of alloying with tungsten carbide powder, the hardening mechanism can be subdivided into two regimes: for the low tungsten concentration in the alloyed layers the hardness is increasing due to the martensitic transformation, while for the high tungsten concentration the increase in hardness is mainly resulted from the higher carbide amount in the alloyed layers. Abrasive wear tests on layers alloyed with tungsten carbide indicate that the wear resistance of martensite hardened layers is comparable with that of conventional hardened 100Cr6 steel and the wear resistance of tungsten carbide composite layers is comparable with taht of sintered WC/Co hard metals. By these results a microstructure can be produced as required to suit different wearing situations.For many industrial applications it is sufficient to have a small area of wear resistant surface. For this reason, cheap low carbon steel is chosen for the partial laser surface alloying. Laser alloying experiments of low carbon steel (16MnCrS5) were carried out by powder injection (WC/Co 88/12) and with graphite precoating for comparison. In addition, melt injection of tungsten carbide was used to produce a composite layer with hard tungsten carbide particles embedded in tough metal matrix. Detailed material investigations (metallographical, electromicroscopical and EDX-analyses) were under-taken on the samples obtained with these methods.The experimental results indicate that for the samples alloyed with carbon, the hardness increases due to martensitic transformation. In the case of alloying with tungsten carbide powder, the hardening mechanism can be subdivided into two regimes: for the low tungsten concentration in the alloyed layers the hardness is increasing due to the martensitic transformation, w...