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研究了时效热处理对激光立体成形17-4PH(0Cr17Ni4Cu4Nb)沉淀硬化不锈钢组织及力学性能的影响。光学显微镜(OM)和扫描电子显微镜(SEM)观测结果表明,经过时效热处理后,激光立体成形17-4PH不锈钢的微观组织主要由淬火马氏体、回火马氏体和第二相强化质点组成。随着时效温度的升高,构成基体的马氏体板条变得更加细小均匀,淬火马氏体向回火马氏体的转变增多,且板条间的第二相质点逐渐粗化,数量逐渐增多;晶界变得更加清晰、细长。热处理后材料的塑性比沉积态有显著的提高。480℃时效处理时,材料的强度、硬度达到最大值;随着时效温度的升高,材料的强度、硬度逐渐降低,塑性逐渐提高。热处理后试样的拉伸断口均呈现韧性断裂特征,并且随着时效温度的升高,纤维区和剪切唇越来越大,韧窝尺寸及深度逐渐增大。
The effect of aging heat treatment on microstructure and mechanical properties of 17-4PH (0Cr17Ni4Cu4Nb) precipitation hardened stainless steel was investigated. Optical microscope (OM) and scanning electron microscopy (SEM) observations show that after aging heat treatment, the laser microstructure of 17-4 PH stainless steel is mainly composed of quenched martensite, tempered martensite and second phase strengthening particles . As the aging temperature increases, the martensite laths that make up the matrix become more and more uniform, the transformation from quenched martensite to tempered martensite increases, and the second phase particles between the laths gradually coarsen. The number Gradually increased; grain boundaries become more clear, slender. The plasticity of the material after heat treatment is significantly higher than that of the deposited state. When the aging treatment at 480 ℃, the strength and hardness of the material reach the maximum value. With the aging temperature increasing, the strength and hardness of the material gradually decrease, and the plasticity gradually increases. After heat treatment, the tensile fracture of the samples showed ductile fracture characteristics. With the increase of aging temperature, the fiber area and the shear lip became larger and larger, and the dimple size and depth increased gradually.