理论计算了超声检测时不同频率声波和不同耦合层厚度时的声强往复透射率,分析了耦合层厚度变化对不同频率声波回波高度的影响,表明回波高度将随耦合层厚度的减小而上升,且耦合层厚度发生同样变化时高频探头的回波高度变化大于低频探头的回波高度变化.直探头试验证明,缺陷波高随着探头压力的加大而上升,且探头压力发生同样变化时高频探头的回波高度变化大于低频探头的回波高度变化.因此,使用高频探头检测时,保证缺陷定量时的探头压力与探伤灵敏度校准时一致,对于缺陷准确尺寸评定至关重要.

The reciprocating transmittance of sound intensity during ultrasonic testing was theoretically calculated for different frequencies and different coupling layer thickness.The influences of the thickness of coupling layer on the height of echo for different frequencies sound waves were analyzed.This result indicates that the height of echo rises when the thickness of coupling layer decreases and it will rise higher while using probes of high-frequency.The experiments of straight probe indicate that the height of defect echo rises when the pressure on probe increases and this phenomenon will be more obvious using high-frequency probes.So it is significantly important when evaluating the size of the defect to ensure that the pressure on high-frequency probes is the same as the pressure on carrying out sensitivity calibration.