Abstract
The welding current (A), arc voltage (V) preheating (°C), travel speed (mm·min-1) and net heat input (Qnet) were evaluated, on the strength and morphology of the fracture in experimental HSLA Cr-Ni steel welded joints, with commercial (ERS70S-6) filler metal and robotic GTAW technique. The samples were characterized by uniaxial stress tests, stereoscopy and Digital Image Processing (DIP). The results showed that the resistance to fracture of the experimental steel was exceeded by 18.39% by applying Qnet 0.520 (kJ·mm-1) and the combination of: 200 A, 12.7 V, 25 °C and 180 mm min-1, which influenced the ductile fracture morphology and topology. While the low Qnet (0.200-0.208 kJ·mm-1) favors instantaneous deformation of the welded joints with fracture in the weld bead as the major defect.
Highlights
High-strength steels have been an option for armor plating in the ballistics industry and used in the core material of projectiles, due to their low cost and mechanical properties [1]
The mechanical resistance of High Strength and Low Alloy (HSLA) to Cr-Ni steels is directly associated with their alloying elements; in particular to Cr and Ni, which are essential to increase their mechanical resistance [3], since Cr increases the resistance to corrosion of alloys in oxidizing media and Ni produces greater elongation under stress and improves resistance to fracture [4]
For the assembly of parts in HSLA steels, it is common to use Gas Tungsten Arc Welding (GTAW) because it is free of slag, presents less impurities and porosity and high production with welding robots [5] [6] [7]
Summary
High-strength steels have been an option for armor plating in the ballistics industry and used in the core material of projectiles, due to their low cost and mechanical properties [1]. For the assembly of parts in HSLA steels, it is common to use Gas Tungsten Arc Welding (GTAW) because it is free of slag, presents less impurities and porosity and high production with welding robots [5] [6] [7]. This process maintains high temperatures for a longer time and the heat input is higher compared to others [8], it is important to evaluate the Qnet
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