【摘要】 系统探究了RWL34粉末冶金马氏体不锈钢在900～1200℃奥氏体化过程中的碳化物演变规律及性能变化，在此基础上研究了150～600℃回火后的性能变化。结果表明：随淬火温度升高，M₂₃C₆型碳化物逐渐溶解并遵循Ostwald熟化机制粗化；1080℃淬火后溶解速率加快，至1200℃淬火时大量溶解，未溶碳化物尺寸粗化至2.03μm,单位面积内碳化物数量显著减少。随淬火温度升高，强度和硬度整体均呈先升后降趋势。950℃淬火时，细小弥散碳化物的Orowan强化占主导，抗拉强度达峰值1750.02 MPa; 1080℃淬火时，固溶强化与Orowan强化共同作用，显微硬度达峰值816.14 HV;当淬火温度超过1100℃后，碳化物大量溶解，冷却后的基体组织由马氏体主导转变为以奥氏体为主，抗拉强度降低，而伸长率则因奥氏体的良好塑性显著增加，在1200℃淬火时达5.73%。回火后，硬度在180℃回火时达峰值740.50 HV;抗拉强度在300℃回火时达最大值1901.74 MPa,并在400℃和550℃回火时分别出现二次硬化与二次强化；伸长率在300℃回火时为2.53%,600℃回火时升至3.25%。综合硬度、强度的匹配，最佳热处理工艺为1080℃淬火+300℃两次回火，获得硬度639.57 HV、抗拉强度1901.74 MPa的优异综合性能，满足刀具钢使用要求。更多还原

【Abstract】 The carbide evolution and properties changes of RWL34 powder metallurgy martensitic stainless steel during austenitizing at 900-1200 ℃ were systematically investigated. Further, the mechanical properties of the steel after tempering at 150-600 ℃ were also investigated. The results show that with the increase of quenching temperature, M₂₃C₆ carbides gradually dissolve and coarsen following the Ostwald ripening mechanism; the dissolution rate accelerates after quenching at 1080 ℃, and a large number of carbides dissolve at 1200 ℃, with the undissolved carbides coarsening to 2.03 μm and the number of carbides per unit area decreasing significantly. With the increase of quenching temperature, the strength and hardness generally increase first and then decrease. After quenching at 950 ℃, the Orowan strengthening of fine dispersed carbides dominates, and the tensile strength reaches a peak value of 1750.02 MPa. After quenching at 1080 ℃, solid-solution strengthening and Orowan strengthening work together, and the microhardness reaches a peak of 816.14 HV. When the quenching temperature exceeds 1100 ℃, a large number of carbides dissolve, and the matrix microstructure after cooling transforms from martensite-dominated to austenite-dominated, resulting in decreased tensile strength, while the elongation increases significantly due to the good ductility of austenite, reaching 5.73% at after quenching 1200 ℃. After tempering, the hardness reaches a peak of 740.50 HV after tempering at 180 ℃, the tensile strength reaches a maximum of 1901.74 MPa after tempering at 300 ℃, and the secondary hardening and secondary strengthening appear when tempering at 400 ℃ and 550 ℃, respectively. The elongation is 2.53% when tempering at 300 ℃ and increases to 3.25% when tempering at 600 ℃. Considering the comprehensive balance of hardness and strength, the optimal heat treatment process is quenching at 1080 ℃ + double tempering at 300 ℃, achieving excellent comprehensive properties with hardness of 639.57 HV and tensile strength of 1901.74 MPa, which meets the service requirements of tool steels.更多还原