Hossein Mostaan - Arak University
Mahdi Rafiei - Advanced Materials Research Center, Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran.
Mohammad Emadi - Advanced Materials Research Center, Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran.

Mechanical properties optimization of weldment such as tensile strength, microhardness and impact toughness are of prime importance in welding technology. The main aim of this research is to investigate the microstructural evolutions and also optimization of tensile strength in dissimilar laser welding between Inconel ۶۲۵ superalloy and AISI ۴۳۰ ferritic stainless steel. It was found from the microhardness measurements that the hardness is increased form AISI ۴۳۰ base metal toward Inconel ۶۲۵ superalloy. This can be attributed to the inherent higher hardness of Inconel ۶۲۵ and formation of very fine structure and also fine precipitations in the weld metal which are distributed uniformly. Formation of very fine structure and precipitations is due to the rapid cooling rate of the weld metal during laser welding process. Design of experiment based on the response surface method was used in order to optimize the tensile strength of the weld joints. Three process parameters i. e. pulse duration, lamping current and also travel speed were chosen as the main parameters which are considerably affecting the tensile strength of the weld joint. It was found that the lamping current has a higher impact on the tensile strength of the weld joints.

Inconel ۶۲۵, ۴۳۰ ferritic stainless steel, Optimization, Laser Welding, Dissimilar joint