Weldability of high nitrogen stainless steel

Abstract

The purpose of this paper is to give a short survey of the influence of nitrogen in stainless steel welds. The review covers: the levels of nitrogen in weld metal, the influence of nitrogen on stainless steel weld metal characteristics such as weld defects, corrosion resistance and mechanical properties. High nitrogen steel welding must consider the risk of nitrogen escape from the weld pool. Avoiding nitrogen losses may be accomplished by controlling the shielding gas, welding parameters and the compositions of filler metal. An increase of nitrogen in the weld metal decreases the delta-ferrite content. The reduction of delta-ferrite in austenitic weld metals will result in an increase in the solidification cracking susceptibility. However, the role of nitrogen in affecting the solidification cracking susceptibility of fully austenitic weld metals is unclear. Nitrogen additions increase the pitting corrosion resistance in weld metals whereas they decrease resistance to stress corrosion cracking because of delta-ferrite reduction. Nitrogen also improves mechanical properties in weld metals. However, the presence of nitrides may be detrimental to the mechanical properties of stainless steel welds.