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分析了GCr15SiMn钢不同热处理组织的超声波归一化功率谱。对于正火、退火和高温回火组织 ,40 %～ 5 0 %脉冲回波能量均集中在 8 2 812 5MHz,其中正火和退火组织在中低频段的能量分布相差较小 ;而对于低温回火组织 ,超过 5 0 %的能量集中在 1 0 9375MHz,中、高频段的能量分布相差较大。分析认为 ,超声波在不同组织中传播时的散射不同 ,导致超声波在不同频率上的干涉 ,可能是造成上述现象的主要原因。利用该方法有望实现显微组织的超声无损区分。
The normalized power spectra of different heat-treated tissues of GCr15SiMn steel were analyzed. For normalizing, annealing and tempering, the energies of 40% ~ 50% of the pulse echoes are concentrated at 8 2 812 5 MHz, of which the difference of energy distribution between normalizing and annealing in the middle and low frequency ranges is small; In the fire organization, more than 50% of the energy is concentrated in 109375MHz, and the energy distribution in the middle and high frequency bands is quite different. The analysis shows that the scattering of ultrasound waves in different tissues is different, resulting in the interference of ultrasound waves at different frequencies, which may be the main reason for the above phenomena. Using this method is expected to achieve ultrasonic non-destructive differentiation of microstructures.