Microstructure and properties of Fe-Cr-Ni gradient alloy steel by direct laser deposition

doi:10.13251/j.issn.0254-6051.2023.02.001

Abstract

Abstract: An outside-strong but inside-tough 12CrNi2Y-50Cr6Ni2Y-70Cr8Ni2Y gradient alloy steel specimen was prepared by direct laser deposition technology. Then the microstructure, interfacial adhesion, hardness gradient distribution and wear resistance of the specimen were studied by means of metallographic microscope, scanning electron microscope, transmission electron microscope, hardness tester and friction testing machine. The results show that the 12CrNi2Y-50Cr6Ni2Y-70Cr8Ni2Y gradient alloy steel specimen with metallurgical bonding at the gradient transition interface and no crack inclusion defects is successfully prepared under the optimized laser deposition parameters. The microstructure of the specimen shows a change trend from (granular bainite+lath bainite+a small amount of martensite) to (lath bainite+lath martensite) to (lath martensite+plate martensite), the corresponding hardness changes as gradient distribution of 356 HV0.2 → 551 HV0.2 →712 HV0.2, and the volume wear rate as gradient distribution of 2.01×10^-4 mm³·N^-1·m^-1 → 1.33×10^-4 mm³·N^-1·m^-1 → 0.71×10^-4 mm³·N^-1·m^-1. In the prepared gradient alloy steel specimen, due to the increase of C and Cr content, the hardness of the specimen shows a gradient distribution from low to high, and the wear resistance of the surface working layer is improved by nearly 2.8 times, so the outside-strong but inside-tough requirements is realized by gradient distributions of microstructure and properties. The obvious element diffusion of small-size C atoms near the transition interface of gradient alloy steel specimen promotes the metallurgical bonding of gradient interface.

Key words: direct laser deposition, gradient alloy steel, microstructure evolution, hardness gradient distribution, metallurgical bonding

CLC Number:

TG142.2

Zhan Di, Chen Suiyuan, Song Xiuwen, Chen Xueting, Wang Mei. Microstructure and properties of Fe-Cr-Ni gradient alloy steel by direct laser deposition[J]. Heat Treatment of Metals, 2023, 48(2): 1-9.

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