The effect of preheat & post weld heat treatment on the laser weldability of AISI 420 martensitic stainless steel

• Laser welding of martensitic stainless steel is a very challenging process.
• An effect of post weld treatment on properties of laser weldment was investigated.
• The desired properties of weldment have been achieved by controlling cooling rate.
• The post-weld treatment could be responsible for reducing microcrack propagation.

The martensitic stainless steels are widely used in many industries with their excellent mechanical properties and sufficient corrosion resistance. These steels usually are used for a wide range of applications like nuclear power plants, steam generators, mixer blades, pressure vessels, turbine blades, surgical tools, instrument manufacturing and so on. Contrary to good mechanical and corrosion properties of martensitic steels, poor weldability and cold cracking sensitivity are major problems that are faced in joining of these steels. In this study, the weldability of AISI 420 (X30Cr13) martensitic stainless steel by CO2 laser beam welding method has been investigated. Effects of pre and post weld heat treatments on mechanical properties and microstructure of laser welded AISI 420 martensitic stainless have also been determined. As a conclusion, it was determined that pre and post weld heat treatments sufficiently improved the mechanical properties of the welds.