Mechanical Behavior of Armor Steel Gas Metal Arc Welding Joints Performed by Nickel-Chromium and Low-Alloy Steel Filler Metals

The objective of this work is to improve the mechanical properties of armor steel welded joints by manufacturing dissimilar joints using a nickel-iron-chromium filler material. This work analyzes the hardness, tensile strength, impact resistance, and high-cycle fatigue behavior of an armor Cr-Mn steel, welded with the gas metal arc welding process. In the purpose of evaluating the advantage of dissimilar joints, the armor Cr-Mn steel was welded using two different filler materials: a commonly used filler material, ER70S-6, and a nickel-iron-chromium filler material, ERNiFeCr-2. The microstructural characteristics of the welded joints were analyzed and discussed. The ERNiFeCr-2 welds presented an increase in yield stress (20%), ultimate tensile stress (30%), and impact resistance (16%) in comparison with the ER70S-6 joints. However, an approximately 50% ductility decrease was also reported. It is argued that the superior strength and limited ductility of the ERNiFeCr-2 welds was attributed to the presence of carbides in the austenitic matrix of the weld metal. In terms of fatigue performance, both welded joints presented similar behavior.