烧结和锻造态Fe–2Cu–0.5C–0.11S材料的组织与力学性能研究

Microstructure and mechanical properties of sintered and forged Fe–2Cu–0.5C–0.11S materials

采用国产原料制备粉末冶金烧结态和锻造态Fe–2Cu–0.5C–0.11S材料,考察该材料的密度、显微组织、静态力学性能及动态超声疲劳性能。结果表明,粉末锻造工艺可以有效提高材料密度,锻件的平均密度可达到7.75 g/cm^3,其相对密度可达到98.7%;烧结件和锻件的显微组织主要由珠光体和铁素体组成,但锻件中的孔隙明显较少;锻件的力学性能相对于烧结件得到明显提升,其抗拉强度、屈服强度、延伸率及硬度分别为1018 MPa、778 MPa、4.0%及HB 206,比烧结件分别提高了155%、145%、167%及87%;锻件在106、107和108周次下相应的超声疲劳强度为437.7 MPa、351.1 MPa和281.7 MPa,比烧结件分别提高了82%、70%和59%;在相同疲劳寿命下,锻件的疲劳强度一直高于烧结件,但随着疲劳寿命的提高,两者之间的差值变小;烧结件和锻件在拉伸时均表现出脆性断裂的特征,同时存在微观塑性变形区域。

Sintered and forged Fe–2Cu–0.5C–0.11 S materials were prepared from domestic raw materials.Density,microstructure,static mechanical properties,and dynamic ultrasonic fatigue property of the materials were investigated.The results show that forging can effectively improve the density of the parts.An average density of 7.75 g/cm3（relative density of 98.7%） is obtained.The microstructures of the sintered and forged samples are mainly composed of pearlite and ferrite,but the porosity of the forged samples is obviously less.The mechanical properties of the forged samples are improved significantly compared with those of the sintered samples.The tensile strength,yield strength,elongation,and hardness of the forged samples are 1018 MPa,778 MPa,4.0%,and HB 206,respectively,which increases by 155%,145%,167%,and 87% than those of the sintered samples.Ultrasonic fatigue strength of the forged samples for 106,107,and 108 weeks is 437.7 MPa,351.1 MPa,and 281.7 MPa,respectively,which increases by 82%,70%,and 59% than those of the sintered samples.In the same fatigue life,the fatigue strength of the forged samples is higher than that of the sintered samples,but the differences decrease with the increase of fatigue life.The sintered and forged samples all show the characteristics of brittle fracture in general,and the microscopic plastic deformation exists both in the sintered and forged samples.