Specimens of 304 stainless steel exposed to solution treatment at 1080℃ for 1,2h have been evaluated employing ultrasonic testing in order to discuss the feasibility and ultrasonic nondestructive characterization parameters for average grain size in 304 stainless steel solution treatment product.The results showed that the ultrasonic velocities decreased gradually and the attenuation coefficient increased apparently after solid solution treatment.The velocities continued decreasing slowly and the attenuation coefficient increased further with increasing solution treatment time at the same temperature.The spectral analysis exhibited an obvious decrease of the peak frequency and a gradual increase of the peak amplitude after solution treatments.The above studies are mainly attributed to the effects of the solution treatment to the grain size and the effects of the grain size to the propagation of ultrasonic wave through materials.Based on the least square method,the linear relationships between transverse wave velocity vt,longitudinal wave velocity v1 and the average grain size were obtained vt =-0.49254d+3188.40138,v1 =-0.07632d+5772.88964; meanwhile,the relevance of the attenuation coefficient to the average grain size was also described in the studied specimens as followed as α =1.2605 × 10-15d6.5012 +0.0995.%304不锈钢在1080℃下分别固溶1,2h,水淬后进行超声检测,以探讨无损评价304不锈钢固溶产物晶粒尺寸的可行性与表征参数.研究表明:固溶处理后,超声波速度逐渐降低,衰减系数明显增大；延长固溶时间,声速缓慢降低,衰减系数继续增大.频谱分析表明:固溶处理后,峰值频率明显降低,峰值幅度不断增大.分析认为:上述现象的产生与固溶处理对材料晶粒尺寸的作用以及晶粒尺寸对超声波传播的影响作用相关.基于最小二乘法拟合得到:横波声速v1、纵波声速v1与平均晶粒尺寸d线性相关:v1=-0.49254d+3188.40138,v1=-0.07632d+5772.88964;衰减系数与晶粒尺寸符合如下规律:α=1.2605×10-15d6.5012+0.0995.
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