Development of experimental and theoretical forming limit diagrams for warm forming of austenitic stainless steel 316

In sheet metal forming, the formability is limited by the onset of localized necking and it is important to know the limit up to which the material can be formed. Forming limit diagram (FLD) offers a convenient and useful tool to predict the forming behavior of the sheet metals, which can be enhanced by forming at elevated temperatures. This paper is focused on the development of FLD for austenitic stainless steel (ASS) 316 at 300 °C, which has been experimentally determined to be the most suitable temperature for warm forming of ASS 316. Experimental FLD has been constructed by performing hemispherical dome punch tests on different width specimens. Theoretical FLDs have been developed using Marciniak-Kuczynski analysis based on Hill's and Barlat's yield criteria and compared with the experimental FLD. Theoretical FLD based on Barlat's yield criterion is found to be in a close agreement with the experimental FLD. These FLDs can be used for designing various warm forming processes on ASS 316.