蠕墨铸铁RuT400与RuT450的拉伸与疲劳性能

Tensile and Fatigue Properties of Vermicular Graphite Cast Irons RuT400 and RuT450

蠕墨铸铁因良好的力学和物理综合性能而被广泛应用于内燃机缸盖、缸体等构件,其最主要的失效形式为疲劳失效。选取两种应用较广的RuT400和RuT450缸盖用材料,进行室温拉伸和高周疲劳试验,分析了两种材料拉伸性能和疲劳性能的差异,并研究了裂纹萌生与扩展规律。研究发现:相对于RuT400,RuT450的抗拉强度和疲劳强度均较高;RuT400和RuT450的拉伸和疲劳断裂方式相同,两者在拉伸和疲劳性能上的差异主要与微观组织有关。随着珠光体含量的提高,蠕墨铸铁的抗拉强度呈指数升高趋势,疲劳强度先降低后升高。研究可为工业生产选材提供依据,即可根据强度与珠光体含量之间的关系进行材料的选取和制备。

Vermicular graphite cast iron is widely used in cylinder head and block of internal combustion engine because of its good mechanical and physical comprehensive properties,whose main failure behavior is fatigue failure.Two such kinds of materials RuT400 and RuT450 were selected for tensile and high cycle fatigue tests at room temperature.The differences between the two materials in tensile and fatigue properties were analyzed,and the crack initiation and propagation mechanism of the materials were studied.It was found that the tensile strength and fatigue strength of RuT450 were higher than these of RuT400.The tensile and fatigue fracture pattern of RuT400 and RuT450 were the same,and the difference in their tensile and fatigue properties were mainly related to the microstructure.With the increase of pearlite content,the tensile strength of vermicular graphite cast iron increased exponentially,and the fatigue strength decreased first and then increased.The study can provide the basis for industrial material selection,that is,the selection and preparation of materials can be performed on the basis of the relationship between strength and pearlite content.