Automatic TIG welding of austenitic stainless steels in nitrogen and nitrogen-based gas mixtures

作者：Zorc B^*

来源：Revista de Metalurgia (Madrid), 2011, 47(1): 29-37.

DOI：10.3989/revmetalmadrid.0962

• TIG welding
• Austenitic stainless steels
• Nitrogen
• Hydrogen

The paper treats studies of TIG gas-shielded arc welding using pure nitrogen, N-2 + 5-20 % Ar gas mixtures and N-2 + 2-10 % H-2, gas mixtures. A weld root shielding was provided by nitrogen gas. Welding in N-2 requires by 40 % lower welding current than welding in argon. The study showed that porosity was an issue due to overalloying of N-2 in the weld pool; it can, however, be avoided with adequate welding parameters, particularly sufficiently high welding speed and controlled low heat input. The microstructure of all-weld metal is fully austenitic (gamma). Hydrogen reduces nitrogen solubility in the weld pool and produces an austenitic-ferritic (gamma+delta) microstructure. Titanium increases nitrogen solubility in the weld pool and strongly reacts with nitrogen. Consequently, there is a high fraction of TIN inclusions in the weld metal.

• 出版日期2011-2