1.1？本文件规定了设计、制备和使用预裂纹试样的程序，用于通过在上升载荷或上升位移下进行的试验来研究金属对应力腐蚀开裂（SCC）的敏感性。在恒定载荷或恒定位移下进行的试验在ISO 7539-6中有处理。 本文中使用的术语“金属”包括合金。 1.2？由于需要限制裂纹尖端的塑性，预裂纹试样不适合评估薄板或线材等薄产品，通常用于较厚的产品，包括板材、棒材和锻件。它们也可用于通过焊接连接的零件。 1.3？可以用在加载点施加单调增加的载荷或位移的设备对预裂纹试样进行定量应力。1.4？预裂纹试样的一个特别优点是，它们允许获得数据，从该数据可以估计承受已知应力的已知几何形状的部件的临界缺陷尺寸，超过该临界缺陷尺寸可能发生应力腐蚀裂纹。它们还能够确定应力腐蚀裂纹扩展的速率。 1.5？该试验的一个主要优点是它考虑了动态应变对应力腐蚀开裂阈值的潜在影响。 1.6？在足够低的加载速率下，通过该方法确定的应力腐蚀开裂敏感性阈值应力强度因子KISCC可以小于或等于通过恒定载荷或位移方法获得的阈值应力强度因子，并且可以更快速地确定。

1.1？ This document specifies procedures for designing, preparing and using pre-cracked specimens for investigating the susceptibility of metal to stress corrosion cracking (SCC) by means of tests conducted under rising load or rising displacement. Tests conducted under constant load or constant displacement are dealt with in ISO 7539-6. The term “metal” as used in this document includes alloys. 1.2？ Because of the need to confine plasticity at the crack tip, pre-cracked specimens are not suitable for the evaluation of thin products such as sheet or wire and are generally used for thicker products including plate, bar, and forgings. They can also be used for parts joined by welding. 1.3？ Pre-cracked specimens can be stressed quantitatively with equipment for application of a monotonically increasing load or displacement at the loading points. 1.4？ A particular advantage of pre-cracked specimens is that they allow data to be acquired from which critical defect sizes, above which stress corrosion cracking can occur, can be estimated for components of known geometry subjected to known stresses. They also enable rates of stress corrosion crack propagation to be determined. 1.5？ A principal advantage of the test is that it takes account of the potential impact of dynamic straining on the threshold for stress corrosion cracking. 1.6？ At sufficiently low loading rates, the threshold stress intensity factor for susceptibility to stress corrosion cracking, KISCC, determined by this method can be less than or equal to that obtained by constant load or displacement methods and can be determined more rapidly.