An estimation of stress corrosion cracking in mild steels by x-rays

Specimens of mild steels, containing the carbon below 0.21%, were plastically deformed in uniaxial tension, then broadening of various X-ray diffraction lines due to the stress corrosion in boiling 35% NaOH was observed. The experimental results indicate that the full width of half maximum intensity (FWHM) of several lattice planes, such as (642), (721)/(633)/(552), (631), (220) and (211), increases evidently as the immersion time increases and decreases slightly after visible crack formation. Although the nature of such a relationship is not simple, it appears to be associated with the anisotropy of deformation in crystalline aggregates, since it has been found that the FWHM of these particular diffraction planes broadens more readily than that of other planes. In practical application, an estimate of stress corrosion cracking may be got from the broadening of susceptible planes to corrosion. (author)