Influence of nitrogen content on the pit formation and pit propagation in the welded joints of X5CrNi18‐10 stainless steel

Abstract

The influence of welding current and nitrogen content in argon shielding gas on the resistance of the welded joint (weld metal and heat‐affected zone [HAZ]) of the stainless steel X5CrNi18‐10 to the formation and growth of pits was investigated. Also, the susceptibility of the welded joint to intergranular corrosion was examined. Pitting corrosion resistance indicators were determined based on anodic potentiodynamic polarization measurements in NaCl + Na2SO4 solution, while susceptibility to intergranular corrosion was determined by the potentiokinetic method with a double loop (DL EPR). SEM/EDS was used to analyze the microstructure. It has been shown that higher nitrogen content in shielding gas leads to an increase in the resistance of welded joints (weld metal and HAZ) to the pit formation. However, an improvement in the resistance to the pit formation leads to a decline in the resistance of the welded joint to pit growth. An explanation of this phenomenon is proposed. Also, it was shown that the increase of the welding current increases the susceptibility of the welded joint to intergranular corrosion, while the higher nitrogen content has no effect.

Corrosion behavior of high- and low-chromium steel grinding balls in chloride solution

“…The passive film on the surface of S3 (stainless cast iron because this steel contains 15.14 wt.% Cr and 2.56 wt.% C), in a solution containing a high concentration of chloride ions (3% NaCl solution), is not stable enough under anodic polarizations, so pits are formed. Pits are formed at favourable places in the microstructure of the tested stainless steel, such as the boundaries of MnS inclusions with the surrounding matrix, as well as on the other inhomogeneities, as liquations on the steel surface [33]. During the polarization measurements (LSV method), localized forms of corrosion (pitting corrosion) occurred, so the obtained values of the corrosion current density (jcorr) cannot be used to calculate the general corrosion rate (vcorr) of the tested samples.…”