黑色金属零件的材料安全系数,通常是材料强度与所受应力之比。在涉及到疲劳应用的场合,由于此时需要考虑平均应力和交变应力,因而安全系数的计算就复杂化了。通常疲劳安全系数可用图解法来决定,本文介绍直接的简便计算法。在图1(修正后的戈德曼图)中,先画二条失效线,一条是疲劳失效线,它是由纵坐标上取材料的持久极限S_n与横坐标上取材料强 The material safety factor of black metal parts is usually the ratio of material strength to stress. When it comes to fatigue applications, calculation of the safety factor is complicated by the fact that the average stress and the alternating stress need to be considered at this time. Usually fatigue safety factor can be used to determine the graphic method, this article describes the direct and easy calculation. In Figure 1 (the modified Goldman diagram), first draw two failure lines, one is the fatigue failure line, which is taken by the vertical axis of the material on the long-lasting limit S_n and take abscissa on the material strength