961材料实验室硬度与现场硬度的差异性分析

Analysis on hardness difference of 961 material test at laboratory and field

针对实验室布氏硬度试验结果与现场硬度结果差异较大的问题,从人、机、料、法、环、测等方面进行分析,以期找到造成差异的根本原因。分析结果表明:现场硬度试验受限于锻件性能、磨削器材以及其他方面的原因,难以达到实验室硬度试样表面的平整度、平行度和粗糙度,致使两者结果差异较大;由于961材料锻件硬度较高(325~368 HBW),锻件表面进行磨削时仅将锻件表面氧化皮打磨,难以保证锻件表面脱碳层(脱碳层深度多在0~0.3mm,最厚一般不超过1 mm)被完全去除,脱碳层会降低读取的硬度值,这也导致现场硬度试验结果与实验室结果产生较大差异。

In view of the large difference between the results of hardness test at the laboratory and the field,the results from the aspects of man,machine,material,method,environment,and mea⁃surement were analyzed,in order to find the primary cause of the phenomenon.The results showed that the field hardness test was limited by forging property,grinding equipment,and other reasons,it was difficult to reach the surface flatness,parallelism,and roughness of the laboratory hardness sample,resulting in a large difference between the two results.Due to the high hardness of 961 material forgings(325~368)HBW,when grinding on the forging surface,if only the oxide skin of the forging surface was grinding away,it was difficult to ensure that the decarburization lay⁃er on the forging surface(the depth of the decarburization layer was mostly between 0~0.3 mm,and the maximum was generally not more than 1 mm)was completely removed,the decarbonized layer reduced the hardness value,which also led to a large difference between the results of the hardness field test and those of the laboratory.