ADI Lost-Foam: Synergy of Process and Material

Abstract

A consortium of SME and RTD partners from Germany, Poland, Italy and Finland was established in the ambit of the fifth European framework programme for the development of a process that combined Lost-Foam with a high performance ADI – Austempered Ductile Iron Cast Iron. In the Lost-Foam process foam patterns are used as models for complex and near net shape castings. These models are coated with a special refractory paint. The models are surrounded by unbonded sand and then filled with liquid metal. As the alloyed ductile iron melt decomposes the foam, the coating material is of great importance for the effective extraction of the foam decomposition products. By means of a posterior special heat treatment it is possible to achieve tensile strengths ranging from 800 to 1600 MPa with elongations ranging from 1 % to 12 %. The main achievements of the performed investigations were the development of the alloy and respective heat treatment parameters for the base ductile iron as well as a suitable coating material. Moreover, these investigations showed that it is possible to produce ADI castings capable of achieving the same mechanical properties as forged steel crankshafts with a significant weight reduction. Additionally, the production of such castings through the Lost-Foam process have a yield of more than 87 % as opposed to the typical yield of the traditional green sand process which can reach 55 %.