中文摘要：

粉末锻造是一种新型高性能的精密塑性成形技术，但其成形时的特殊性导致目前缺乏完善的、普遍适应的粉末锻造成形理论。通过对还原铁粉烧结多孔体预成形坯锻造镦粗成形致密实验，研究了不同初始相对密度、不同高径比、不同摩擦条件对预成形坯锻造镦粗成形、致密的影响规律。得到了粉末锻造镦粗的断裂极限准则，绘制出了断裂极限应变迹线，并着重分析了初始相对密度、高径比和摩擦因子对镦粗断裂极限的影响，确定了镦粗成形极限工艺参数曲线。实验研究结果为粉末锻造预成形坯与模具的设计、工艺参数的优化奠定了理论基础，并提供了有价值的实验数据。

英文摘要：

Powder forging is a new-type and high-performance plastic forming technology. But, there is still no a perfect universal theory of powder forging because of its deforming particularity at present. The deformation and dcnsification laws of upsetting are researched based on experimental results of powder forging of deoxidize Fe porous material at the different initial conditions which include friction factor, relative height and relative density. The local strain limit criterion for the cracking on surface and the correlative curve have been achieved followed by the specialized analysis for the effect of friction factor, relative height and relative density on cracking strain limitation. The limit process parameters are confirmed for the cracking limitation based on experimental results of powder forging. With experimen- tal results, the design of mould and powder forging preformed blank can be optimized and the valuable data from experiment establishes the foundation for the optimization of technological parameters, too.