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一、引言 过去、对采用离心铸造的高铅青铜轴瓦（或铜铅合金轴瓦）的轴瓦钢背的热处理不够重视,一般认为只要进行时效处理就可以了。但我们在实践中发现,采用离心铸造法主产的高铅青铜轴瓦及铜铅合金轴瓦,由于钢壳预热温度及合金浇铸的温度高,在浇铸过程中为了防止铅的偏析必须采用快速激冷的方法,因此钢背表面得到了“淬火效应”,硬度提高,韧性降低。尤其是采用15号甚至20号碳钢作为瓦背材料时,钢背表面硬度常高达HRC30～45,不但给以后的切削加工带来困难,而且由于浇铸后轴瓦内应力较大,在加工过程中轴瓦形状和尺寸会产生变化,精度受到一定程度的影响。更严重的是,由于“淬火效应”引起的钢背硬度提高、韧性降低的现象是导致轴瓦在使用过程中产生断裂甚至碎裂的重要原因之一。图1为用20号钢制成的ND_（2）主轴瓦装车运行17万公里后轴瓦碎裂的实例。类似这样的轴瓦碎裂事
I. INTRODUCTION In the past, the heat treatment of the bearing steel of the high-lead bronze bush (or copper-lead alloy bearing bush) cast by centrifugal casting did not pay enough attention. It is generally accepted that the aging treatment should be carried out. However, in practice, we found that the main production of high-lead bronze bearings and copper-lead alloy bearings by centrifugal casting method, due to the preheating temperature of the steel shell and the high temperature of the alloy casting, in the casting process in order to prevent the segregation of lead must be fast shock Cold method, so the steel back surface has been “quenching effect”, increased hardness, toughness decreased. In particular, the use of 15 or even 20 carbon steel as the tile back material, the steel back surface hardness often up to HRC30 ~ 45, not only to the subsequent cutting difficult, but also because of casting after the stress within the bearing in the processing Bearing shape and size will change, the accuracy is affected to some extent. More seriously, due to the “quenching effect” caused by increased hardness of the steel back, the reduction of toughness is one of the important reasons causing the bearing during the use of the fracture or even fragmentation. Figure 1 shows an example of a bearing rupture after loading 170,000 km of ND_ (2) main bearing made of 20 steel. Similar to this fragmentation of the bearing shell