30CrMnSiA钢回火组织对超声信号影响的试验研究

30CrMnSiA钢具有较高的强度和良好的韧性，是重要的飞机结构受力部件，常在淬火后不同温度回火处理状态下使用。本研究取淬火态的30CrMnSiA钢在200~700 ℃进行回火，观察其金相组织，并使用超声检测方法对不同回火组织进行检测，分析超声波传播特征（纵波声速、声衰减系数、底波频移）与回火温度、组织变化之间的关系。结果表明:随回火温度提高，30CrMnSiA组织依次为回火马氏体、回火屈氏体、回火索氏体、铁素体+珠光体，硬度逐渐降低；受回火脆性的影响，在540~620 ℃回火得到的回火屈氏体超声检测特征参数值呈大幅度波动；其他回火组织进行超声检测时，随回火温度的升高，超声声速呈增大趋势，底波频移呈下降趋势。

Experimental Study on Effect of Tempered Microstructure on Ultrasonic Signal of 30CrMnSiA Steel

30CrMnSiA steel, with high strength and good toughness, is an important stressed component of aircraft structure and is often used under tempering conditions of different temperatures after being quenched. In this study, the quenched 30CrMnSiA steel was tempered between 200 ℃ and 700 ℃ to observe its metallographic structure, and the ultrasonic testing method was used to detect the different tempered structures, the relationship between ultrasonic propagation characteristics (longitudinal wave speed, sound attenuation coefficient, bottom wave frequency shift) and tempering temperature and microstructure changes was analyzed. The results showed that with the increase of tempering temperature, the 30CrMnSiA microstructure was tempered martensite, tempered troostite, tempered sorbite, ferrite + pearlite in turn, and the hardness decreases gradually; Because of the influence of tempering brittleness, the ultrasonic testing characteristic parameters of tempered troostite tempered between 540 ℃ to 620 ℃ fluctuated greatly. The ultrasonic velocity increased and the bottom wave frequency shift decreased with the increase of tempering temperature when the others tempered microstructure were tested.