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航空工业等部门,对所用金属材料的机械性能要求比较严格,经常需要测定所选用金属材料的条件屈服强度σ_(0.2),以保证所设计和制造出来的飞行器等在多次正常使用的情况下不致积累过大的永久变形;断裂力学的研究和应用中,为了解裂纹端附近塑性区的范围,以便估计塑性区的影响,也普遍地要求测定金属材料的条件屈服强度σ_(0.2);至于高强度金属材料的应力腐蚀问题,常以材料条件屈服强度的大小作为该材料对应力腐蚀敏感性的一个标志,所以也需要准确地测定条件屈服强度σ_(0.2)。条件屈服强度σ_(0.2),简称屈服强度(为与物理屈服强度相区别,后者简称为屈服点σ_s,是微量塑性变形抗力指标的一种。其起始的定义是:在拉伸试验过程中,使试样计
Aviation industry and other departments, the mechanical properties of metal materials used more stringent requirements often need to determine the conditions of the selected metal material yield strength σ_ (0.2), in order to ensure that the design and manufacture of aircraft in the case of many normal use In the research and application of fracture mechanics, in order to know the range of the plastic zone near the crack end so as to estimate the influence of the plastic zone, it is also generally required to determine the conditional yield strength σ_ (0.2) of the metal material. As for The problem of stress corrosion of high strength metal often takes the yield strength of the material as a sign of its sensitivity to stress corrosion. Therefore, it is also necessary to accurately measure the yield strength σ_ (0.2). Conditional yield strength σ_ (0.2), referred to as the yield strength (as distinguished from the physical yield strength, the latter referred to as the yield point σ_s, is a trace of plastic deformation resistance index of its initial definition is: during the tensile test In the sample