金属板材液压胀形声发射检测

本文应用声发射技术检测了Ａ３钢、２０钢、４５钢、４０６钢板材液压胀形全过程，所得数据表明液压胀形全过程存在两个屈服阶段，两次变形转移。第一阶段的屈服是中心区与凹模入口区的屈服，第二阶段的屈服是中心区与凹模入口区之间的环形区域的屈服，第一次转移是中心区、凹模入口区向环形区转移，第二次转移是环形区向中心区转移。胀形深度一声发射计数率曲线有两个峰值区，两个平静区，第二个平静区预示着材料的破坏。

Acoustic Emission Testing of the Hydrulic Bulging of Metallic Materials

The whole process of hydraulic bulging A3,20,45 and 406 steel is studied by meansof acoustic emission technique.The data obtained show that there exist two yielding stagesand two deformation shifts during the whole process of hydraulic bulging, The first yieldingoccurs in the ring state zone between the central zone and the concave die entrance.The firstshift takes place from the central zone and concave die entrance to the ring state zone, thesecond shift takes place from the ring state zone to the central zone. The bulging depth-ring-down count rate curve has two peak zones and two calm zones.The second calm zone foretellsthe damage of materials.