丰收35拖拉机液压泵中的偏心轴采用20Cr钢经气体渗碳淬火处理。按照工艺要求渗碳淬火后偏心轴的表面硬度应为HRC58～63。可是,几年来常常发现渗碳淬火件存在软区,其硬度值先HRC50左右,有时虽然淬火后检测硬度合格,但经磨削0.25毫米(单边)后却发现有软区。产生上述弊病的偏心轴数量约占20％以上,长期以来是生产中伪一个老大难问题。 Harvest 35 tractor hydraulic pump eccentric shaft 20Cr steel by gas carburizing quenching. In accordance with the requirements of the process after carburizing quenching the surface hardness of the eccentric shaft should be HRC58 ~ 63. However, in recent years, carburizing and quenching parts are often found in soft areas, the hardness of the first HRC50 or so, although the hardness after quenching test qualified, but after grinding 0.25 mm (unilateral) but found soft areas. The number of eccentric shafts that generate the aforementioned ills is about 20% or more. For a long time, this has been a long-standing issue for production.