Microstructure and hardness of laser forming repaired 300M steel Available to Purchase

Microstructure and micro-hardness distribution in single-track laser forming repaired 300M steel were investigated. The microstructure in the repaired zone consisted of the lath martensite. There showed no obvious changes for the microstructure in the repaired zone with the increase of the deposited layer. A series of phase evolutions from the bottom to the top of heat-affected zone (HAZ) occurred: the ferrite and a small amount of carbides→ the ferrite and austenite→ lath martensite. With the increase of the deposited layer, the amount of the carbides reduced and the amount and size of the austenite increased gradually in the HAZ, and the morphology of the austenite changed from strips-like to mesh-like. There were the same variation trends of the hardness from the substrate to the repaired zone between the single-track single-layer repaired and single-track multi-layer repaired specimen. The hardness in the substrate zone was the lowest, it increased rapidly from the bottom to the top of the HAZ. The hardness of the repaired zone was the highest, and varied a little from the bottom to the top of the repaired zone.