ELECTROCHEMICAL AND STRESS-CORROSION PROPERTIES OF DUPLEX STAINLESS-STEELS MODIFIED WITH TUNGSTEN ADDITION

Addition of tungsten to duplex stainless: steels (DSS) is known to sup press formation of the brittle secondary phases that may have a negati ve effect on general corrosion and stress corrosion cracking (SCC) pro perties. The effects of tungsten addition to DSS on microstructural, e lectrochemical, and SCC properties were examined. On aging, tungsten a ddition reduced the amount of alpha-phase precipitation, while enhanci ng precipitation of the chi phase. The beneficial effect of tungsten s ubstitution for molybdenum in DSS was demonstrated. art electrochemica l polarization behaviors and pitting corrosion resistance. Results wer e more apparent in aged specimens than in homogenized ones when tested at room temperature because of precipitation behavior of the secondar y phases. DSS were susceptible to SCC in boiling 35% magnesium chlorid e (MgCl2) solution but not in boiling 10% sulfuric acid (H2SO4) + 35,0 00 ppm chloride) solution The beneficial effect of tungsten tungsten a ddition on SCC properties of homogenized DSS in boiling 35% MgCl2, sol ution was evident.