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为研究高温回火对SA533B(0.15C-1.39Mn-0.28Si-0.50Mo-0.59Ni-Fe,wt%)钢力学性能及微观组织的影响,采用拉伸试验、夏比V型缺口冲击试验检验了钢板在660~720℃回火60 min后的力学性能,膨胀试验测定相变点,用SEM、TEM表征了不同状态下的微观组织。结果表明:SA533B钢的Ac_1、Ac_3、Ms、Mf点分别为630、816、446和280℃,在910℃水淬后的组织为板条马氏体。回火温度范围可以选择在660~710℃。当回火温度低于710℃时,由于组织仍然保持着铁素体板条形貌,并且板条总体的尺寸较小,整体强度与韧性仍然匹配较好。当回火温度高于710℃时,回火过程中形成大量富碳奥氏体,冷却过程中可转变为孪晶马氏体,强度显著提高,韧性剧烈降低。
In order to study the effect of high temperature tempering on the mechanical properties and microstructure of SA533B (0.15C-1.39Mn-0.28Si-0.50Mo-0.59Ni-Fe, wt%) steel, tensile test, Charpy V-notch impact test The mechanical properties of the steel sheet after tempering at 660-720 ℃ for 60 min were measured. The transformation point was measured by the expansion test. The microstructure was characterized by SEM and TEM. The results showed that the Ac_1, Ac_3, Ms and Mf points of SA533B steel were 630, 816, 446 and 280 ℃, respectively. The microstructure of the steel SA533B was lath martensite after water quenching at 910 ℃. Tempering temperature range can be selected at 660 ~ 710 ℃. When the tempering temperature is below 710 ℃, the overall strength and toughness still match better because the microstructure of the ferrite remains in the ferrite strip and the overall size of the strip is small. When the tempering temperature is higher than 710 ℃, a large amount of carbon-rich austenite is formed during the tempering process, and the martensite can be transformed into twin martensite during the tempering process. The strength is remarkably increased and the toughness is drastically reduced.