弹簧钢55SiCr面缩不合实例分析

Analysis of Unqualified Area Reduction Case of Spring Steel 55SiCr

弹簧钢广泛应用于汽车、航空航天、铁路等各个领域,不仅要求具有高的强度和疲劳极限,而且要有一定的韧性和塑性。某公司生产的弹簧钢55SiCr线材,做力学性能检验时,面缩值低于标准要求(标准大于31%),强度在合格范围内,面缩为23%。为了找出面缩值低的原因,采用扫描电镜、金相显微镜等设备对试样分析,结果表明,拉伸白点是面缩值低的主要原因。另外,本文又介绍了拉伸白点的主要特点,即拉伸白点是在外加应力作用下诱发形成的,多以夹杂物或微裂纹为裂纹源扩展,并对此提出了相应的改进建议。

Spring steel is widely used in automobile,aerospace,railway and other fields,which is required not only to have high strength and fatigue limit,but also to have certain toughness and plasticity.When the mechanical properties of spring steel wire 55SiCr is tested in a company,the area reduction is 23%which is lower than the standard requirement(greater than 31%),and the strength is in the qualified range.In order to find out the reason for the low area reduction,the sample is analyzed by scanning electron microscope(SEM)and metallographic microscope,and the results show that the tensile flakes is the main reason for the low area reduction.In addition,this paper also introduces the main characteristics of tensile flakes,that is,tensile flakes are induced by external stress,and most of them take inclusions or micro cracks as crack sources,and puts forward corresponding improvement suggestions.