Effects of B contents on the microstructure and hardness of Fe-Cr-Co hardfacingalloy coating on CK-۴۵ steel as a substrate

In this work, the effects of boron (B) content on the microstructure and hardness of the Fe-Cr-Co-B hardfacing alloycoating were investigated via TIG welding . The samples of the CK-۴۵ were coated without B then boron were addedin the coatings. The microstructures of the coatings observed by metallographic microscopy and field emissionscanning electron microscopy(FESEM), electron backscatter diffraction (BSD) and (SE) mode. In addition, thehardness of the coatings were determined using a Vickers hardness tester. The results of this research showed thatthere is a limitation in using boron element as a hardening material in Fe-Cr-Co hardfacing alloy system. Accordingto the results of this research, the use of ۳% wt. of boron in welding-filler cause Phase formation Fe۲B andsignificantly increases the hardness of the coating, but higher values formation FeB in matrix related to decreasethe hardness of the coating surface.Result demonstrate that adding ۳ %wt. boron to Fe–Cr–Co alloy can form theFe۲ B phase with higher hardness, which significantly reduces the production cost and improves strength of thealloy.

Keywords:

Hardfacing , Boron , Cobalt.