在缺陷评定中,一般都用 COD 评定方法,而把 K 判据方法限制在应力比较低的范围内使用。为了扩大 K 判据方法的使用范围,文[1]通过宽板试验,对有残余应力情况下的 K 有效性进行验证后得到:当外加应力σ_t=0.8σ,和残余应力σ_R=0.6σ时,K 判据仍有效.文[2]分析了 K 判据的优点和 COD判据所存在的问题,提出了用于压力容器缺陷评定的统一 K 判据方法.本文用对比的方法证明了:当压力容器的缺陷部位由载荷引起的应力σ_t≤1.5σ_s(σ_t 不包括残余应力)时,K 判据是适用的. In the defect assessment, COD assessment methods are generally used, and the K criterion method is limited to a lower stress range. In order to expand the scope of application of the K criterion method, Wen et al. [1] verified the validity of K with residual stress through a wide-plate test. When the applied stress σ_t = 0.8σ and the residual stress σ_R = 0.6σ , The K criterion is still valid. [2] Analyzed the advantages of K criterion and the existing problems of COD criterion, put forward a unified K criterion method for pressure vessel defect assessment.This paper proves by contrast: When the pressure vessel defect site by the load caused by stress σ_t ≤ 1.5σ_s (σ_t does not include residual stress), K criterion is applicable.