PM low alloy steel samples were prepared by die-wall pressing-sintering and double press/double sinter (DP/DS) processing. The density, mechanical properties, microstructure and fractography were analyzed. The results indicate that the density of the sintered alloys with 0.8% graphite addition prepared by die-wall pressing-sintering is the maximum 7.15 g/cm3, and the ultimate tensile strength is 406 MPa; when prepared by DP/DS processing, the density can achieve 7.53 g/cm3, the ultimate tensile strength is 611 MPa, and the elongation is increased, too. The samples prepared by DP/DS processing has fewer pores and the pores are more rounded, and there are lots of dimples distributed in fracture surface, thereby the strength and plasticity of the alloys are better.%通过在预合金钢粉中加入C等元素,采用模压-烧结和复压复烧2种方法制备粉末冶金低合金钢,并对其密度、显微组织、力学性能和断口形貌进行分析.研究结果表明:对于添加质量分数为0.8％C的合金粉末,用普通压制-烧结法制备的样品密度最高为7.15 g/cm3,抗拉强度为406 MPa;而用复压复烧法制得的样品密度可达7.53 g/cn3,抗拉强度为611 MPa,伸长率也有很大提升；复压复烧法制得的样品孔隙较少且圆滑平直化,断口分布有大量的韧窝,因此,合金的强度和塑性均较高.
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