Statistical analysis related to the quantification of microhardness and the percentage of martensite after the application of welding

Stainless steels are used to manufacture components for the automotive industry, equipment and components of steam turbines for the generation of electrical energy; for this reason, it is important to consider the percentage of martensite and microhardness obtained after applying the arc welding processes. In this paper, specific variations of voltage and wire feed speed values are selected to evaluate their effect in the gas metal arc welding (GMAW) process in an AISI 409 ferritic stainless steel. The analyzed parameters are the percentage of martensite and the microhardness obtained after the application of welding. The characterization of the welded specimens is carried out by electrolytic polishing and modified Berahas colored chemical etching to stain the martensite phase. The main objective of this document is to design a full factorial experiment to demonstrate that the percentage of martensite and microhardness increases or decreases according to the wire feed speed and voltage variations. The experimental data fit a normal distribution with a confidence level of 84.704% obtained from the analysis of variance (ANOVA) in the percentage of martensite and 89.404% in microhardness.