A parametric study on laser-assisted preheating and post-weld heat treatment to enhance the mechanical properties of AISI 1075 high-carbon steel for electric vehicle manufacturing applications

Abstract

Electric vehicles (EVs) are a major step toward sustainable mobility, primarily by reducing emissions and improving energy efficiency. In this context, material selection is crucial for ensuring durability, recyclability, and minimizing environmental impact. Although composite materials are effective in reducing weight, their limited recyclability remains a significant challenge. In contrast, high-carbon steels such as AISI 1075, offering high strength, wear resistance, recyclability, and cost-effectiveness, can be a promising alternative to ultra-high strength steel (UHSS) and composite materials. However, the welding of high-carbon steels like AISI 1075 is susceptible to brittleness and welding defects. Laser welding and laser heat treatment have been recognized as effective methods to overcome these limitations. This study investigates the feasibility of laser welding for AISI 1075, with a particular focus on the effects of laser-based pre-weld heating (PH) and controlled post-weld heat treatment (PWHT) on the macro-structure and mechanical properties. These methods improve the internal structure while offering significant energy and time savings compared to conventional techniques. A thermal camera and a Time-Temperature-Transformation (TTT) diagram were utilized to optimize laser parameters and monitor cooling. Additionally, mechanical tests, including tensile and hardness testing, were conducted to assess the mechanical properties of the welded specimens. The findings highlight the critical role of pre-weld heating and post-weld heat treatment in improving the weldability of high-carbon steels. This study provides a structured framework for implementing laser welding and heat treatment as sustainable and cost-effective manufacturing solutions for EV applications.