衬板用Fe-24Mn-7Al-1C耐磨钢的热处理工艺对组织和性能影响

Effect of heat treatment process on microstructure and property of Fe-24Mn-7Al-1C wear resistant steel for lining plate

采用金属模具浇注新型Fe-24Mn-7Al-1C轻质奥氏体耐磨钢。用X射线衍射分析、显微组织及断口形貌观察、析出物能谱分析,研究余热水韧处理和常规水韧处理对新型钢种的组织、力学性能、断裂机理的影响。结果表明:晶界处粗大的未溶碳化物为(Fe,Mn)3Al C的κ碳化物,该碳化物在950℃后迅速溶于奥氏体基体中。余热水韧处理温度850℃左右,其冲击韧性值(V型缺口)108.3 J/cm2,表面硬度为219 HB(心部硬度217 HB),抗拉强度为784.6 MPa,屈服强度408.9 MPa,断后伸长率为53.8%;断口由准解理区域和大小不一的韧窝断裂区域组成。常规水韧处理时在1050℃保温1 h后综合性能最佳,其冲击韧性值(V型缺口)231.3 J/cm2,硬度为205 HB,抗拉强度为809.6 MPa,屈服强度410.9 MPa,断后伸长率为56.9%;常规水韧处理的断口形貌呈韧窝状,断裂机理为典型微孔聚集型断裂。

The light-weight Fe-24Mn-7Al-1C austenitic wear-resistant steel was cast by using metal mould. Microstructure and properties of the steel after treated by casting heat remained water toughening and conventional water toughening treatment were examined by X-ray diffraction（ XRD）,optical microscopy（ OM）,scanning electron microscope（ SEM） and energy dispersive spectrometer（ EDS）analysis. Results show that the discontinuous coarsened boundary carbides of（ Fe,Mn）3Al C,which is the κ-carbides at the grain boundaries,are quickly dissolved after water toughening treatment at 950 ℃. After casting heat remained water toughening treatment at850 ℃,the following mechanical properties of the steel are obtained： the impact toughness（ V-notch） of 108. 3 J / cm^2,surface hardness of 219 HB（ core hardness of 217 HB）,tensile strength of 784. 6 MPa,yield strength of 408. 9 MPa and elongation of 53. 8%,and the fracture mechanism of quasi cleavage fracture and dimpled fracture is observed on the impact fracture surface. The steel has the best combination of strength and toughness after conventional water toughening treatment at 1050 ℃ for 1 h with the impact toughness（ Vnotch） of 231. 3 J / cm^2,hardness of 205 HB,tensile strength of 807. 2 MPa,yield strength of 410. 9 MPa and elongation of 56. 9%,and the fracture mechanism is typical microvoid coalescence fracture.