低碳钢氢腐蚀的超声衰减检测及统计分析

ULTRASONIC ATTENUATION MEASUTEMENTS OF HYDROGEN ATTACK ON LOW CARBON STEEL AND THEIR STATISTICAL ANALYSIS

以20G低碳钢为实验用材,经450℃和500℃ 18MPa氢气中分别暴露240,480和720小时,发生不同程度氢蚀。用衰减法对氢蚀试样进行超声波检测,对检测结果进行统计分布分析。结果表明,超声衰减系数测定值呈正态分布,随氢蚀程度加深,正态分布均值μ增大,方差σ也增大。μ可以作为氢蚀程度的量度。另外,还给出了μ与σ的显著性检验方法和置信区间。

20G low carbon steel was chosen for the experimental material and exposed in hydrogen gas at 18MPa at 450℃ and 500℃ for 240,480 and 720 hours respectively in order to obtain different degrees of hydrogen attack.Ultrasonic attenuation measurements of hydrogen attack on all samples were taken.The data obtained were analysed statistically. The results showed that the experimental values of ultrasonic attenuation coefficient at different placed on one sample obeyed the normal probability distribution.Both the mean value μ and the variance σ in the normal distribution increases with the exposure time. Therefore,the values of μ could be used for predicting the degree of hydrogen attack.The test of significance and confidence interval for the μ and σ are discussed.