首页|Measurement of degree of sensitization in post-weld heat treated 13Cr-4Ni martensitic stainless steel clad using double loop electrochemical potentiokinetic technique
Measurement of degree of sensitization in post-weld heat treated 13Cr-4Ni martensitic stainless steel clad using double loop electrochemical potentiokinetic technique
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NSTL
Elsevier
In this paper, the susceptibility to intergranular corrosion (IGC) of 13Cr-4Ni martensitic stainless steel clad deposited by submerged arc welding was studied in the as-welded condition and after post-weld heat treats (PWHT) at 420, 500, 540, and 580 degrees C. Microstructural studies showed a martensitic matrix, about 20% delta-ferrite and carbide precipitates in the microstructure under the as-welded condition. The results of the double loop electrochemical potentiokinetic technique revealed that the PWHT process significantly increased the degree of sensitization (DOS). The highest DOS corresponded was 87.9% in the sample treated at 500 degrees C. PWHT at temperatures higher than 500 degrees C returned the DOS to lower values. PWHT at 500 degrees C and below promoted the decomposition of delta-ferrite, and hence some new chromium carbides precipitated at delta-ferrite and martensite interfaces, whereas tempering at temperatures higher than 500 degrees C accounted for carbides precipitation at martensite lath boundaries owing to the formation of tempered martensite. The DOS value decreased with increasing PWHT time due to chromium diffusion to chromium-depleted regions. Also, the potentiodynamic studies showed an inverse relationship between the DOS and pitting potential; the higher DOS, the lower the pitting potential.
NSTL
Elsevier
