Microstructures and tensile properties of laser cladded AerMet100 steel coating on 300 M steel

Abstract

A layer of AerMet100 steel was coated on the surface of forged 300M steel using laser cladding technique. The chemical compositions, microstructures, hardness and tensile properties of this AerMet100/300M material were systematically investigated. Results show that the composition of the AerMet100 clad layer is macroscopically homogeneous, and a compositional transition zone with width of 150μm is observed between the clad layer and heat affected zone. Microstructures in transition zone transform from the fine needle-like bainite in 300M steel to the lath tempered martensite in AerMet100 clad layer. Microstructures in heat affected zone also gradually change from the thick plate bainite and blocky retained austenite (unstable heat affected zone) to fine needle-like bainite and film-like austenite (stable heat affected zone) due to different thermal cycle processes. Thick plate bainite together with blocky retained austenite in unstable heat affected zone reduce the strength and ductility of AerMet100/300M material. However, the tensile specimens, consisting of clad layer and stable heat affected zone, show slightly inferior mechanical properties to 300M steel. Ductile fracture exists in AerMet100 clad layer while quasi-cleavage fracture occurs in the stable heat affected zone.