研究目的
Investigating the microstructure and fatigue behavior of a laser additive manufactured 12CrNi2 low alloy steel.
研究成果
The as-built LMD 12CrNi2 steel exhibited a microstructure mainly consisting of ferrite and Cr23C6 carbides, with no preferred texture due to complex heat flux during fabrication. Fatigue cracks initiated from subsurface defects, with propagation zones showing a mixed mode of transgranular and intergranular fracture. The strain localization predominantly occurred at grain boundaries, and fatigue cracks originated from grains with the {123}<111> slip system due to its prior activation.
研究不足
The study focuses on the as-built condition of LMD 12CrNi2 steel without post-processing heat treatment, which may limit the understanding of how heat treatment affects the material's properties. The research also primarily investigates high cycle fatigue behavior, leaving out other fatigue regimes.
1：Experimental Design and Method Selection:
The study involved the preparation of 12CrNi2 low alloy steel by laser melting deposition (LMD) and the investigation of its high cycle fatigue fracture mechanisms. Microstructural analysis was conducted to establish a process-microstructure-property relationship.
2：Sample Selection and Data Sources:
Gas-atomized 12CrNi2 alloy steel powder was used as the deposition material. The substrate material was a Fe-based alloy 35CrMo steel.
3：List of Experimental Equipment and Materials:
A Ytterbium Laser System (YLS-6000) equipped with a computer-aided control system, a powder feeder, and a powder delivery nozzle was used for fabrication. Optical microscopy (OM, Hitachi, Japan), SEM (ZEISS Merlin) equipped with an electron backscatter diffraction (EBSD) detector, and X-ray diffraction (XRD-7000, Rigaku, Japan) were used for characterization.
4：Experimental Procedures and Operational Workflow:
The samples were fabricated using optimized processing parameters. After fabrication, no post-processing heat treatment was conducted. The as-built samples were cut into fatigue test samples, polished, and etched for microstructural examination.
5：Data Analysis Methods:
The microstructural characterization was examined by OM and SEM. The phase constituent was identified via XRD. Fatigue tests were performed at room temperature using an M-3000 high-cycle fatigue testing machine. Fractography analysis was carried out on the fatigue samples.
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