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球墨铸铁淬火后常用测定洛氏硬度来检验质量。这是由于,测硬度的方法比较简单、方便,而且不必破坏工件就能测知金属材料的软硬;因此,硬度试验已是工厂成批检查产品质量的重要手段之一。但是,笔者在实践中发现,淬火球墨铸铁测定洛氏硬度,于硬度压痕周围能产生显微裂纹。显微裂纹的存在,削弱了材料的性能,使工件在使用过程中不需要经过裂纹的萌生阶段,就直接开始裂纹的扩展阶段以致
Ductile iron commonly used to determine Rockwell hardness after quenching to test the quality. This is because the method of measuring hardness is relatively simple and convenient, and the hardware and software of metal materials can be detected without destroying the workpieces. Therefore, the hardness test is one of the important measures that the factory checks the product quality in batches. However, the author found in practice, quenching ductile iron Rockwell hardness, micro hardness cracks can occur around the indentation. The existence of micro-cracks, weakening the performance of the material, so that the workpiece does not need to go through the crack initiation stage, the crack initiation phase directly