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1.绪言由于铸铁材质的高级化和稳定质量技术的显著提高,许多铸锻钢件被铸铁件代替。其原因之一是决定机械性能的测定方法逐渐被确立,保证高精度的质量已成为可能。但现在日本工业标准中规定使用的 Y 试块是由破坏试验来削定机械性能的,和铸件本身的强度不一致,还存在有难以在短时间内简单地得出结果等许多问题。近年来,由于超声波试验装置宽频带探头和宽频带接受放大器等的研制,可适用于对衰减大的材质检测而得到显著的进步。根据超声波的传播速度(以下称声速)或衰减值等的变化探测铸铁的石墨组织,推测球铁的机械性能已有一些报导。可是它们多为同一铸造过程,且基体组织几乎为一定的铸铁。因此,本研究对铸造过程、石墨形态和基体组织等不同的多种铸铁作了声速测定,为判断机械性能指出了方向。
1. INTRODUCTION Many cast steel forgings have been replaced by castings due to the high quality of cast iron and the significant increase in stable quality technology. One of the reasons is that the determination of the determination of mechanical properties has gradually been established, to ensure high-precision quality has become possible. However, the Y-block specified in the Japanese Industrial Standards now has mechanical properties deteriorated by a failure test, which is inconsistent with the strength of the castings itself. There are also many problems such as difficulty in finding the results in a short period of time. In recent years, due to the development of wide-band probes and wideband receiver amplifiers for ultrasonic testing devices, it is applicable to the significant improvement of material detection with large attenuation. According to the ultrasonic propagation velocity (hereinafter referred to as speed of sound) or attenuation changes in the detection of graphite cast iron, speculated that the mechanical properties of ductile iron have been reported. However, they are mostly the same casting process, and the matrix structure is almost constant cast iron. Therefore, the present study measured the speed of sound of various cast irons, such as the casting process, graphite morphology and matrix structure, pointing out the direction for judging the mechanical properties.