中文摘要：

针对Mn18Cr18N铜高温摩擦因子难以合理确定的现实问题，用圆环镦粗法对Mn18Cr18N钢的不同润滑条件下的高温摩擦因子进行了测定，得出了试验数据，并结合大型护环热扩挤成形工艺进行了有限元数值模拟分析，有效地指导了生产实践。

英文摘要：

Aiming at the practical problem which the high temperature friction factor of Mn18Cr18N Steel is difficult to determine reasonably, some tests for measuring friction factors by ring upsetting under different lubrication conditions are carried out. The corresponding test data are obtained. Based on that, the forming process of expand and extrusion for heavy retaining rings is analyzed successfully with the numerical simulation method, which instructs the productive practice.