Lubrication and friction conditions vary with deformation during metal forming processes. Significant macro-variations can be observed when a threshold of deformation is reached. This study shows that during the cold compression processing of #45 (AISI 1045) steel rings, the magnitude of friction and surface roughness (R_a) changes significantly upon reaching a 45% reduction in ring height. For example, the R_a of compressed ring specimens increased by approximately 55% immediately before and after reaching this threshold, compared to an 18% or 25%variation over a 35%-45% or a 45%-55% reduction in height, respectively. The ring compression test conducted by this study indicates that the Coulomb friction coefficient μ and Tresca friction factor m are 0.105 and 0.22, respectively, when the reduction in height is less than 45%; and 0.11 and 0.24, respectively, when the reduction in height is greater than 45%.

中文翻译：

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中碳钢冷环压缩试验中摩擦条件的变化

在金属成型过程中，润滑和摩擦条件会随变形而变化。当达到变形阈值时，可以观察到明显的宏观变化。这项研究表明，在＃45（AISI 1045）钢环的冷压加工过程中，当环高度降低45％时，摩擦强度和表面粗糙度（R _a）会发生显着变化。例如，在达到此阈值之前和之后，压缩环样品的R _a大约增加了55％，而高度降低了35％-45％或45％-55％时，R _a的变化为18％或25％，分别。这项研究进行的环压试验表明，库仑摩擦系数μ当高度降低率小于45％时，Tresca摩擦系数m分别为0.105和0.22；当高度降低幅度大于45％时，分别为0.11和0.24。