Multi-criteria Decision Making of Single Point Incremental Forming Process Parameters for Duplex Stainless Steel 2205 Using ARAS and COPRAS Techniques

Duplex stainless steel (DSS) 2205 finds wide application in aircraft industries and for surgical implants. However, the formability of 2205 steel sheets is limited under normal conditions, requiring hot-working to enhance strain hardening at lower temperatures. Furthermore, there is a lack of research on the single point incremental forming process (SPIFP) applied to DSS 2205. Hence, the current study aims to explore the fracture characteristics of 2205 steel sheets using SPIFP, while varying several parameters such as tool type, tool diameter, speed, feed rate, and vertical step down. Optimal process parameter selection holds significant importance due to its potential for cost reduction and enhancement of quality. This choice involves determining suitable process parameters while considering multiple conflicting factors, necessitating the application of the multiple criteria decision-making (MCDM) approach. Hence, this work addresses the MCDM challenge using the additive ratio assessment (ARAS) and complex proportional assessment (COPRAS) techniques. The experiment carried out with two different forming tools such as hemispherical-ended forming tool and ball-ended forming tool, assessment carried out by varying the stated independent parameters. The dependent parameters include straight groove depth, wall angle depth, spring back, formability, and surface roughness. The SPIFP alternatives are assessed using the aforementioned two techniques, and the outcomes are subsequently analyzed. The best possible arrangement was determined using ARAS and COPRAS methods to achieve both maximum and minimum values for all the responses. This arrangement was identified with the hemispherical-ended forming tool and the specific set of process parameters: a tool diameter of 10 mm, a feed rate of 600 mm/min, a speed of 200 rpm, and a vertical step down of 0.6 mm. In 77.78% of instances, the rankings from ARAS are in agreement with the rankings from COPRAS. Notably, the lower and higher orders of rankings are the same, adding an intriguing dimension to the observation. However, the patterns of different dependent variables, influenced by the diversity of independent variables, were not consistent. These intricate mechanisms have been recognized and documented.