engleski

Effect of welding procedure on the pitting suspectibility of stainless steel

The effect of manual arc welding (MAW) and automatic plasma welding (APW) on pitting susceptibility of stainless steel was investigated. Sheet specimens of AISI 304 SS were examined in as welded state (AW) and after following subsequent treatments: - mechanical removal of weld reinforcement and grinding (GR) - mechanical removal of weld reinforcement, grinding, and mechanical polishing (MP) - pickling by HNO3/HF paste (PI) - anodic/cathodic cleaning in H3PO4/H2SO4 solution (EC) - anodic/cathodic cleaning in H3PO4/H2SO4 solution and anodic polishing in the same solution (AP). One half of specimens were additionally passivated in HNO3. Specimens were exposed to FeCl3 solution according to ASTM G48-92. The consequences of the exposure have been analysed separately for the area of the weld (W zone), for adjacent areas with heat tints (HT zone), and for both areas of base metal (BM zone). Following criteria have been used for the evaluation of pitting susceptibility: - average pit depth, ĥp - maximum pit depth, hmax - pits density (average pits number per unit of the observed area), np/S - pitting penetration density (sum of pits depths per unit of the observed area), Σhp/S. The results vary in different directions for single zones depending on the welding procedure and on the surface state. The influences of the welding procedure and of the additional passivation are comparatively weak.

welding; stainless steel; surface state; pitting

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