Corrosion resistance and mechanical properties of nickel-bearing ferritic stainless steels

✍ Scribed by A. P. Bond; H. J. Dundas; E. A. Lizlovs; G. Gemmel; B. Solly

• Publisher: John Wiley and Sons
• Year: 1977
• Tongue: German
• Weight: 886 KB
• Volume: 28
• Category: Article
• ISSN: 0947-5117
• DOI: 10.1002/maco.19770280804

✦ Synopsis

Abstract

Additions of nickel to ferritic steels containing 25–28% Cr and 2–4% Mo increased the impact toguhness especially when more than 2% Ni was present. The effect of nickel content increased up to 4% Ni, the largest addition studied. Steels stabilized with niobium had lower transition temperatures then did corresponding steels stablizied with titanium. Steels containing 4% Ni required annealing at 1050 C to avoid intermetalic compounds. It was also noted that nickel reduced the upper shelf energy in the Charpy impact test and eliminated a sharp transition from ductile to brittle behaviour.

No definite effect of nickel on pitting potential was pound but steels in the series 25Cr‐3.5 Mo‐Ni‐Ti consistenly had more noble pitting potentials and greater resistance to crevice corrosion than the 28 Cr‐2Mo‐Ni‐Ti steels. Nickel contents of 1 or 2% tended to improve crevice corrosion resistance while larger nickel contents were somewhat ditrimental. Nickel strongly reduced critical current densities for passivity both in l N H~2~SO~4~ and in l N HCL and yielded corresponding increases in resistance to corrosion by these acids. Although 1% Ni or more caused the annealed steels to be susceptible to stress corrosion cracking in MgCl~2~ boiling at 140 C, while the as‐Welded steels containing 4% Ni did not crack in boiling 25% Nacl at pH 1.