Equal channel angular pressing with converging billets—experiment

A new concept of equal channel angular pressing (ECAP) with converging billets is proposed and tested experimentally. In its basic configuration, the new ECAP process uses two equal square input channels converging into a single output channel, which is twice as wide as the input channels so that it can accept two converging billets. The contact surface between converging billets plays the same role as a movable die wall in the output channel of classical ECAP and thus reduces friction and the process force. The process productivity is doubled and material pickup, especially problematic in the output channel, avoided. This paper presents results of experimental trials of the new process using purposely designed tooling incorporated in a horizontal press with three hydraulic cylinders. One pass of ECAP with converging Al 1070 billets has been carried out and the resulting hardness distribution and microstructure examined. It is concluded that the new process is a feasible version of ECAP both in the engineering and the micro-structural terms, with the added benefit of doubled productivity as well as friction and force reduction.