Influence mechanism of parameters process and mechanical properties evolution mechanism of maraging steel 300 by selective laser melting

TLDR: In this article, the influence of process parameters (laser powder, scanning speed and scanning space) on the relative density of maraging steel 300 was investigated first and then a series of block and plate specimens were manufactured.

Abstract: Selective laser melting (SLM) is one kind of additive manufacturing process to fabricate metal parts through laser melting. A maraging steel 300 was manufactured by SLM. And the influence of process parameters (laser powder, scanning speed and scanning space) on the relative density of maraging steel 300 was investigated first. Then a series of block and plate specimens were manufactured. Some specimens were taken as control groups, and others underwent heat treatment by solution treatment (ST) and solution treatment +aging treatment (ST+AT) respectively. The investigation involved microstructure, microhardness, tensile strength and impact toughness. It is shown that: low or high laser power, scanning speed or scanning space all reduced the relative density, and the optimized process parameters could be obtained by orthogonal experiment. After ST, the cellular structure and microscopic segregation disappeared, and the new smaller particles precipitated out after AT. The Ni, Mo and Ti dissolved in the matrix during ST separated out again forming tiny Ni 3 Mo, Fe 2 Mo and Ni 3 Ti particles during AT. The microhardness and tensile strength dropped a little with elongation increasing after ST. While they increased significantly with elongation decreasing after AT. The impact toughness increased little after ST, but decreased sharply after AT.