Non-destructive testing of steel pipes that are long-term exploited according by statistical hardness parameters

Abstract

The features of non-destructive testing of steel pipes with a long service life in terms of dynamic hardness parameters are considered. The limited applicability of normal and lognormal distributions, the Weibull and Gumbel distributions to describe the distribution density of hardness estimates for steels that have been in long-term operation in harsh meteorological and functional conditions of Siberia and the Far North is shown. A number of experiments were carried out on the formation of digital images of the hardness distribution over the surface of the tested products. Hypotheses are formulated regarding the use of such images to assess the current technical state of metal products and the dynamics of its change. The possibility of describing the hardness of steel specimens used for a long time in difficult conditions of Siberia by a weighted sum of two normal distributions has been experimentally proved.