Dynamic strain ageing in C -Mn steels and associated welds. II. Effect on fracture toughness behaviour

Measurement of sensitivity to dynamic strain aging in C–Mn steels by internal friction experiments

“…Nevertheless, in steels the Snoek peak is more complex, due to overlapping of C and N peaks and also due to nitrogen Snoek peak distortion by nitrogen manganese interaction. [7][8][9][10][11][12][13][14][15][16][17] In this case the deconvolution of the different peaks is doubtful and the 5 Ultimate tensile strength DSA sensitivity index versus Snoek peak height for various materials and treatments quantitative determination of free C and N content in the lattice is not reliable. We have therefore plotted the global Snoek peak height versus two different DSA sensitivity parameters defined from an engineering point of view.…”

“…Depending on the diffusion coefficients, the chemical composition of the steels and the strain rate, the temperature range over which DSA occurs can vary from 200 to 350uC. 7,8 This coincidence with the operating temperature range of the secondary lines of pressurised water reactors (PWR), leads to the necessity for a good estimation of the sensitivity to DSA of the in service steels.…”

“…Nevertheless, if they are insufficiently killed, these steels are well known to be sensitive to dynamic strain aging (DSA). This phenomenon, [1][2][3][4][5][6][7][8] induces an increase in flow stress, ultimate tensile strength and work hardening coefficient, as well as a decrease in ductility (elongation, reduction of area) and fracture toughness. DSA is due to the presence of solute atoms, which are able to diffuse over short distances and pin mobile dislocations.…”