The main purpose of this research work is to study the forming limit and fracture behaviour of the AZ31 magnesium alloy, as well as to improve the formability and surface roughness of parts formed using the warm incremental sheet forming (ISF) process. For the ISF process, AZ31 Mg alloy sheets were used. Initially, Taguchi orthogonal L27 arrays were used to design experiments, and a framed multi-objective optimization problem was solved using the grey-fuzzy method. The strain-based forming

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... ure limit diagrams (FFLD) were plotted after a variable wall angle test. The grey-fuzzy reasoning grade (GFRG) is calculated in this study by combining grey relational analysis (GRA) and fuzzy rationale. For the AZ31 Mg alloy, the maximum GFRG value was obtained for the following forming combinations: step depth 0.3 mm, feed rate 500 mm/min, spindle speed 700 rpm, and tool diameter 10 mm. Then, ANOVA was used to determine the importance of parameters on the responses, and it was discovered that the step depth has the greatest influence (68.78%) on GFRG value, followed by the feed rate (16.56%). The fracture behaviour of the Mg alloy was studied using fractographs. Later, FE simulation was used to validate the strain value obtained from experimentation and to investigate the effect of process parameters on responses.