Hydrogen Cracking in Duplex Stainless Steel Weldment

The restraint weld cracking test was conducted to investigate the hydrogen cracking in duplex stainless steels which contain various ferrite/austenite ratio. The gas tungsten arc (GTA) welding was applied with the argon shielding gas containing 10% hydrogen. The effects of preheating or post weld heat treatment (PWHT) on the hydrogen cracking were also tested.The hydrogen cracking occurred in the weld metal with the ferrite ratio higher than 60% using the 10% hydrogen containing shielding gas under the severe restraint condition. The higher ferrite ratio of weld metal produced larger amount of diffusible hydrogen bacause the hydrogen can dissolve in the austenite phase. It was effective for the prevention of cracking to apply the preheating at 473K of the solution treatment at 1373K or to reduce the ferrite ratio by the adjusting the nickel and nitrogen content in the weld metal.