TWI Industrial Member Report Summary 118/1980
By J Honeycombe and T G Gooch
Study has been carried out of the effects of welding on the corrosion and stress corrosion properties of 18%Cr2%Mo titanium stabilised ferritic stainless steel sheet from 2 to 3.5mm thickness and 9mm plate. Welds were made using the manual metal arc, MIG and TIG processes, with matching, austenitic stainless
steel and nickel-based consumables. Intercrystalline, pitting and crevice corrosion resistance of welds was evaluated, using immersion and potentiostatic techniques, with stress corrosion behaviour being assessed using constant load transverse weld tensile samples in MgCl2 and CaCl2 solutions.
Welding promoted some susceptibility to intercrystalline attack. although all welds passed the Strauss bend test criterion for sensitisation. Resistance to pitting and crevice corrosion in FeCl3 were reduced by welding. No stress corrosion was observed in parent material. However, welded joints made with non-matching composition consumables were found to suffer cracking although susceptibility was generally less than that associated with austenitic grades of steel.
It is concluded that in most environmental situations, loss in corrosion properties as a result of welding will not be significant. For highest corrosion resistance, use of matching composition consumables is to be preferred.