Effect of the cooling rate on the microstructure and mechanical properties of high nitrogen stainless steel weld metals

The microstructure and mechanical properties of high nitrogen steel (HNS) weld metals prepared under air- and water-cooling conditions are investigated, and the effect of the cooling rate on these properties is discussed. The results indicate that an increase in the cooling rate could significantly increase the nitrogen content in HNS weld metals, especially for weld metals with a nitrogen content of 0.85%. Moreover, increasing the cooling rate could result in an increase in the tensile strength of HNS weld metals, which is found to be strongly dependent on the nitrogen content of the HNS sample. For high nitrogen austenitic stainless steel welding wire with lower nitrogen content, increasing the cooling rate could significantly improve its tensile strength, but a higher cooling rate has no influence on weld metals with nitrogen content less than 0.58%. The tensile strength of the joint reached 850 MPa.