Microstructure evolution, wear behavior, and corrosion performance of alloy steel gradient material fabricated by direct laser deposition

Abstract

In this paper, the corrosion-wear-resistant alloy steel gradient material for camshaft was successfully prepared by direct laser deposition (DLD). The phase evolution, microstructure characteristics, microhardness, wear behaviors and corrosion resistance of alloy steel gradient material were studied using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), hardness tester, wear tester and electrochemical workstation, respectively. The results showed that phase evolutions with the increase of stainless steel powders from α-Fe + Cr23C6 to α-Fe + Cr23C6 + (Cr, Fe)7C3. The microstructure of the alloy steel gradient material was refined with increasing the stainless steel powders. The preferred texture was weak with the increase of gradient due to the each layer experiencing a variety of complex thermal cycle effects. Meanwhile, the content of high-angle grain boundaries (HAGBs) and the volume fraction of Cr23C6 and (Cr, Fe)7C3 increased with gradient increasing, which promoted the toughness and enhanced the wear reaiatance of the material. In addition, the microhardness distribution of alloy steel gradient material showed a gradient increase from 281 HV to 795 HV along with deposition direction. The wear resistance and corrosion resistance of alloy steel gradient material were extremely improved. The average specific wear rate and corrosion current density of alloy steel gradient material specimen were 0.30 × 10−5 mm3/Nm and 1.3 × 10-7 A cm-2, respectively.