Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Welding parameters

Optimization Process of Double Spots Welding of High Strength Steel Using in the Automotive Industry

Hayder H. Khaleel; Ibtihal A. Mahmood; Fuad Khoshnaw

Engineering and Technology Journal, 2023, Volume 41, Issue 1, Pages 110-120
DOI: 10.30684/etj.2022.134325.1236

Resistance Spot Welding (RSW) is one of the most important welding techniques used in the automotive industry because it is an economic process and is suitable for many materials. Many parameters affect the mechanical and microstructural properties of nugget formation and its strength, like welding current, electrode force, and welding time. Therefore, optimizing the RSW process to get the optimum welding parameters is necessary for automobile manufacturing companies. High-strength steel is widely used in the automotive industry because of its superior characteristics such as high strength-weight ratio, ductility, fatigue, and corrosion resistance. This paper presents an optimization process for RSW using the Taguchi method for high strength low alloy steel (HSLA) DOCOL 500 LA, considered a new steel grade. Two spots were used in this work.The mechanical and microstructural tests are achieved to get the maximum nugget strength, nugget diameter, different welding zones microstructures, microhardness values, and failure modes. The results showed that optimum welding parameters were welding current of 8800 Amp, welding time of 20 cycles, and electrode force of 1900 N. The failure mode for optimum conditions was a full pullout with tearing of the welded sheets because of high plastic deformation and absorbed energy. The maximum microhardness value is in the fusion zone, the heat-affected region, and finally, in the base material due to the nugget zone's rapid melting and solidification process.  

Study of Mechanical Properties of Carbon Steel Plate SA-516 Gr. 70 Welded by SAW Using V-Shape Joint Design

Samir A. Amin; Mohannad Y. Hanna; Abdulaziz S. Khider

Engineering and Technology Journal, 2020, Volume 38, Issue 2, Pages 152-165
DOI: 10.30684/etj.v38i2A.269

Submerged arc welding (SAW) is a fusion type welding and it is considered one of the most important welding types due to its inherent capabilities of high welding speed, high deposition rate, welding large thickness plates owing to its deep penetration characteristic and many other advantages. In this study, the goal was to investigate the effect of welding parameters, namely (welding current and welding speed) as well as the joint design on the mechanical properties (yield stress, bending force on the face of the weldment and hardness of the weld metal. Experiments were conducted employing Design of Expert (DOE) software and Response Surface Methodology (RSM) technique. The experiments were conducted by welding ASME SA-516 Gr. 70 steel plate with dimension (300 mm × 150 mm × 10 mm) depending upon the design matrix developed via the DOE. Results manifested that the optimum process parameters for maximum yield stress, maximum bending force and minimum hardness were at (425 amps) welding current and (35 cm/min) welding speed, where the arc voltage was held constant at (37 volts). The optimum values for the yield stress, bending force and hardness were (474.447 MPa, 36.997 kN and 150 HV), respectively. Finally, it was found that the predicted and experimental results of yield stress, bending force and hardness agree very well according to the ultimate error (1.05%, 1.92%, and 4.25 %), respectively.

Influence of SAW Welding Parameters on Microhardness of Steel A516-Gr60

Sadeq H. Bakhy; Samir A. Amin; Fouad A. Abdullah

Engineering and Technology Journal, 2018, Volume 36, Issue 10A, Pages 1039-1047
DOI: 10.30684/etj.36.10A.4

Submerged Arc Welding (SAW) process is generally used for industries, such as petroleum storage tanks, pressure vessels, and structural components.
Good mechanical properties of welded joint lead to crack-free strong joints. In this research, included angle, current, welding travel speed and arc voltage were utilized as welding parameters to weld ASTM A516 Grade 60 (low carbon steel). The experiments were carried out according to a design matrix that established by DOE (Version10) with RSM technique. Microhardness of welded samples was measured by a Digital Microhardness Tester, and then RSM technique was used to model and optimize the microhardness based on the welding parameters. The results showed that the including angle and welding current have a great effect on the microhardness. The optimum solution for minimum microhardness was found at 450 Amp welding current, 38 cpm welding speed, 34-volt arc voltage and included angle of 60⁰. The optimum value of microhardness was (186.7 HV). Eventually, the experimental and predicted results of microhardness were found in good agreement with 4.6%. maximum error.