Improved mechanical properties of aluminum modified ultra-pure 429 ferritic stainless steels after welding

The microstructure and welding performance of ultra-pure 429 ferritic stainless steels with modified aluminum contents have been investigated. Room temperature tensile mechanical properties after welding improve apparently due to the precipitate of nano-sized TiN and core-shell structure Al2O3-TiN particles which play the important role of precipitate strengthening by dislocation pinning of the weld joint. In steels without the addition of aluminum, although the ultimate tensile strength hardly varies before and after welding, the ultimate tensile strength significantly improves after welding especially for high-Al steel, and laser welding and tungsten inner gas welding show hardly any influence on room temperature tensile strength. The effect of fine grain strengthening is very obvious after laser welding, which contributes to the significantly increased value of micro-hardness of the weld joint. The aluminum modified 429 ultra-pure ferritic stainless steels show good welding performance in consideration of room temperature mechanical properties.