Strengthening and toughening of a 2800-MPa grade maraging steel

摘要

A new high Ni, Ti and low Mo maraging steel based on 13Ni(400) maraging steel has been developed. The optimum heat treatment was found to be cryogenic treatment (CT) at 200 K followed by aging treatment at 773 K for 4 h in as-forged or solution condition. Optical and transmission electron microscopy (TEM) revealed that the precipitates, such as Ni_3(Mo, Ti), were well developed in lath martensite. It achieved strength of 2700 MPa and fracture toughness of above 30 MPa m~(1/2) . The balance among alloy elements and the removal of undissolved coarse particles ensured the good combination of strength and toughness by a normal thermomechanical treatment condition.