一、序言最近,用球铁代替钢材作强度材料的例子很多。在这种情况下,必须考虑各种强度特性,特别是象曲轴等汽车零件承受交变载荷时,疲劳强度是个很重要的问题。因此,在进行强度设计时,必须考虑由零件外型引起的应力集中的大小。与此同时,还必须仔细地考虑材料本身的金相组织的影响。 First, the Preamble Recently, the ductile iron instead of steel as the strength of many examples. Under such circumstances, various strength characteristics must be taken into consideration. In particular, fatigue strength is a very important issue when automobile parts such as crankshafts are subject to alternating loads. Therefore, the strength of the design, we must consider the size of the stress concentration caused by the appearance of the parts. At the same time, the influence of the metallurgical structure of the material itself must be carefully considered.