将三种不同固溶状态下的304不锈钢在650 ℃下敏化处理2, 6, 16 h, 然后进行超声检测, 以探讨无损评价304不锈钢敏化程度的可行性与表征参数。结果表明: 延长敏化时间会使304不锈钢敏化程度增大; 采用衰减系数、峰值频率和峰值幅度这三个指标可以无损表征304不锈钢的敏化程度, 但声速对不同敏化处理条件下钢微观结构的改变不能够响应; 随敏化时间的延长, 钢的衰减系数会不断增大, 原因归结为敏化使得钢的晶界上出现大量铬的碳化物对超声波散射作用增强所致; 峰值频率随敏化时间的延长向高频方向偏移, 其峰值幅度也会明显上升。

304 stainless steel samples in three different solid solution states after sensitization treatment at 650 ℃ for 2, 6 and 16 hours were evaluated employing ultrasonic testing in order to discuss the feasibility and ultrasonic nondestructive characterization parameters for the sensitization degree of 304 stainless steel. The results show that the sensitization degree of 304 stainless steel increased with prolonging the sensitization treatment time. Using attenuation coefficient, peak frequency and peak amplitude could nondestructively characterize the sensitization degree of 304 stainless steel, but ultrasonic velocity could not respond to microstructure changes under different sensitized conditions. With prolonging the sensitization treatment time, the attenuation coefficient increased gradually, which was mainly attributed to the deposition of plentiful chromium carbides along the grain boundaries, increasing the scattering of ultrasonic wave. The peak frequency exhibited a shifting to high frequency direction and the peak amplitude increased obviously with prolonging the sensitization treatment time.