用超塑——等温技术压制模具型腔时,其模具冲头(模芯)材料可参照“比单位压力”(P/σ_2)进行选定。本文通过实验,分析、验证后得出结论:在正常润滑条件下,“比单位压力”一般为(3.0～3.5);为此,在选择模具冲头(模芯)的材料时,其σ_s值应为被压制材料的σ_s值的(3.0～3.5)倍,否则,在超塑——等温条件下压制模具型腔时,冲头将可能产生塑性变形,从而影响模具型腔的尺寸精度。 When the mold cavity is pressed by the superplastic-isothermal technique, the material of the die punch (die core) can be selected according to the “specific pressure per unit” (P / σ_2). In this paper, the experimental, analytical and verification concluded that under normal lubrication conditions, the “specific pressure” is generally (3.0 ~ 3.5); Therefore, in the selection of die punch (core) material, the σ_s value (3.0-3.5) times the σ_s value of the material to be pressed. Otherwise, the punch may be plastically deformed when the mold cavity is pressed under the superplastic-isothermal condition, thus affecting the dimensional accuracy of the mold cavity.