Effect of laser incident energy on microstructures and mechanical properties of 12CrNi2Y alloy steel by direct laser deposition

This work aims to establish the effect of laser energy area density (EAD) as the laser incident energy on density, microstructures and mechanical properties of direct laser deposition (DLD) 12CrNi2Y alloy steel. The results show that the density of DLD 12CrNi2Y alloy steel increases at initial stage and then decreases with an increase of EAD, the highest density of alloy steel sample is 98.95%. The microstructures of DLD 12CrNi2Y alloy steel samples are composed of bainite, ferrite and carbide. With increase of EAD, the microstructures transform from polygonal ferrite (PF) to granular bainite (GB). The martensite-austenite constituent (M-A) in GB transforms from flake-like paralleling to the bainite ferrite laths to granular morphology. It is also found that the average width of laths in finer GB can be refined from 532 nm to 302 nm, which improves the comprehensive properties of DLD 12CrNi2Y alloy steel such as high hardness of 342 +/- 9 HV0.2, yield strength of 702 +/- 16 MPa, tensile strength of 901 +/- 14 MPa and large elongation of 15.2%+/- 0.6%. The DLD 12CrNi2Y material with good strength and toughness could meet the demand of alloy steel components manufacturing. (C) 2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.