An investigation on microstructure and mechanical properties of H62 brass thin-sheet by fiber laser welding: Experiments and multi-scale simulations

Abstract

H62 brass is widely used as an engineering material in electrical components, automotive parts, aerospace and other fields. Many brass products and structures requiring material forming by means of welding. The reliability of the welding process directly affects the quality of the brass welded joints. In this study, a high-power fiber laser system was used for welding tests on thin sheets of H62 brass. Based on the theory of a single control variable with multiple welding parameters, the laser power, the amount of defocusing and welding speed were investigated in relation to the relationship of joint formation, microstructure and mechanical properties. In addition, two kinds of macroscopic segregations were found in some welded joints due to insufficient heat input and subcooling of the melt pool to the submixing gap. In order to further analyze the forming mechanism during the welding process, the physical model was established by finite element and molecular dynamics research methods. Using finite elements, the influence rule of different process parameters on the temperature field was analyzed; molecular dynamics was used to analyze the formation process of the weld from the atomic scale. Ultimately, this study has resulted in welded joints of H62 brass with excellent mechanical properties and no obvious defects through suitable combinations of different process parameters. Most importantly, a multi-scale simulation model has been established to analyze the rules of temperature influence in the weld formation process.