Formability studies of ASS 304 and evaluation of friction for Al in deep drawing setup at elevated temperatures using LS-DYNA

Abstract

Deep drawing is a sheet metal forming operation which involves conversion of flat thin sheet blanks drawn into desired cups. Forming of high strength sheet metal and low weight alloys under warm conditions is in great demand now-a-days and its application has great importance in nuclear plants, cryogenic vessels, heat exchangers, pharmaceutical industries etc. In the Present investigation the austenitic stainless steel (ASS)-304 of different blank diameters is deep drawn under warm condition. It is observed that there is a significant improvement in limiting drawing ratio (LDR) from 2.16 at room temperature to 2.5 at 150°C and drawn cups are determined. In this investigation blanks of different diameters are deep drawn to determine LDR at various temperatures and it was found out that under warm conditions there is a significant improvement in limiting drawing ratio from room temperature to 300°C. In the present investigation the other material IS 737 grade aluminum alloy is drawn at elevated temperature and its formability was investigated in warm condition and it was found that there was a substantial increase in the formability of commercial pure aluminum when drawn at 350°C.For a successful design and simulation by finite element (FE) analysis, it is important to determine reliable friction data for a given lubrication system. Especially when the deep drawing operation is being performed under warm conditions, the prediction of friction becomes complex as its value increases with temperature. By inverse analysis of relating the predicted and measured values of the load-stroke curve this paper presents a practical methodology using the deep drawing test and finite element (FE) analysis to evaluate the coefficient of friction between blank and tooling.