Influence of residual elements on the intergranular stress corrosion cracking of carbon steels
A joint programme between NPL and MPI into the effects of impurities and alloying elements on the intergranular stress corrosion cracking (IGSCC) behaviour of carbon manganese steels in nitrates, carbonates/bicarbonates and hydroxides has been completed. The effects are analysed through surface analysis, electrochemical studies and mechanical tests. Results show that in general, of all the impurities tested (P, S, Sn, Cu and Ni) only phosphorus has any detrimental effect on a typical mild steel. A slight beneficial effect is apparent for Cu. The joint effect of phosphorus and manganese is studied in some detail with 0.4 and 2% Mn alloys. Phosphorus has small adverse effects in certain narrow potential regions. Of the main alloying components, manganese and carbon, the manganese concentration does not significantly influence the IGSCC properties, but that of carbon is critical. Upon cathodic polarisation of the investigated steels in 1N H(2)SO(4) transgranular hydrogen induced cracking (HIC) is observed, which is enhanced by increasing P-content. This effect is caused by an increase of H-activity and H-absorption with increasing bulk content of P. According to these results, the lowering of phosphorus content in carbon steels does not suppress their susceptibility towards IGSCC in nitrates, hydroxides and carbonates in the critical potential ranges. The susceptibility towards HIC can be somewhat diminished by low phosphorus content.
Bibliographic Reference: EUR 11507 EN (1988) MF, 140 pp., ECU 8, blow-up copy ECU 17.50
Record Number: 198910304 / Last updated on: 1994-12-01
Original language: en
Available languages: en