Effect of Vanadium on Microstructure and Mechanical Properties of M2 High‐Speed Steel Prepared by Laser Metal Direct Deposition Forming

Abstract

Herein, M2 high‐speed steel containing vanadium is prepared by laser metal direct deposition forming technology, and the effect of vanadium alloying on the microstructure and mechanical properties of M2 HSS is preliminarily explored. Five kinds of M2 HSS samples with different V contents are prepared on substrates of #45 steel. The macromorphology, microstructure, and phase composition of the samples are characterized and analyzed by scanning electron microscopy energy dispersive spectrometry, and X‐ray diffraction. The M2 HSS samples are mainly composed of martensite, residual austenite, and M2C carbides. After adding different proportions of vanadium, because vanadium is a strong carbide forming element, it is easy to combine with carbon to form MC carbide, resulting in the transformation of carbon‐poor matrix from martensite to ferrite, which makes the microhardness of the sample decrease. After alloying with 2, 4, 8, and 12 wt% V, the grain size is significantly refined due to the precipitation of MC carbides at the grain boundaries, which pinned and inhibited the growth of austenite grains. In terms of wear resistance, the amount of wear decreased by 34.41% for the M2 + 2%V sample and increased for the other V‐modified samples relative to M2 HSS. The impact toughness increased by 9.16%, 85.50%, 51.91%, and 25.19%.

Boosting Mechanical Properties of W6Mo5Cr4V2 Alloy Fabricated by Directed Energy Deposition Through Tempering Heat Treatment

“…Figure 5 displays the XRD analysis of the W6Mo5Cr4V2 alloy, revealing that the alloy comprises martensite, MxC‐type carbides, and retained austenite. [ 20 ] Figure 6 illustrates the microstructures of the cross section of both the deposited and heat‐treated W6Mo5Cr4V2 samples, which exhibit no visible defects such as cracks or pores. The microstructure mainly comprises numerous equiaxed grains and a small amount of cellular grains.…”

“…They pinned the grain boundaries, fixed and refined the grain size, and even suppressed the growth of austenite grains. [ 20 ] Consequently, the hardness and wear resistance of the coating was considerably improved.…”