Microstructural Evolution and Mechanical Properties of Laser-remelted18Ni(200) Maraging Steel During Rapid Solidification and Heat Treatment

Author of the article:ZHONG Haoyu1, YANG Jiawei1, REN Huayong1, XU Quan2, LI Xiaolin1, WANG Zhijun1

Author's Workplace：1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China; 2. ShanghaiInstitute of Electro-Mechanical Engineering, Shanghai 201109, China

Key Words：maraging steel; laser remelting; in-situ remediation

Abstract：As a low-carbon maraging steel, 18Ni(200) maraging steel is widely utilized in aerospace applications because ofits superior mechanical properties, such as high strength and toughness. However, under demanding service conditions, thematerial is prone to wear damage. Laser remelting was employed to perform in situ repair of damaged components, whichsignificantly improved the surface quality and extended their service life. The evolution mechanisms of the microstructureand properties during rapid solidification and heat treatment, key stages of the laser remelting process, were investigated ascritical scientific aspects. An investigation was conducted on the variation patterns of the depth and hardness of theremelted layer under different energy densities. The results indicate that the energy density solely affects the depth of theremelted layer, whereas the microstructure and hardness of the repaired remelted layer demonstrate favourable uniformity.Furthermore, the microstructural evolution in the clad zone and the substrate after heat treatment was elucidated. The resultsreveal a uniform distribution of low-angle grain boundaries and residual stress in both regions, with no stress concentrationobserved at the interface. This demonstrates excellent compatibility between the cladding layer and the substrate,confirming the reliability and effectiveness of the repaired region both before and after heat treatment