Performance of normalization method for steel with different strain hardening levels and effective yield strengths

Normalization method is more convenient than unloading compliance method in determining J-resistance (J-R) curve and fracture toughness of steel. However its performance has not been evaluated for different types of steels. Experimental tests are undertaken and analytical studies are carried out in this work to determine the J-R curve and fracture toughness of various steels using the normalization method, including Weldox700, G350 and G250, which are compared with those determined with the conventional unloading compliance method. It is found in this work that the normalization method is more accurate for steels with high strain hardening exponent and effective yield strength, such as, Weldox700 steel, but is less accurate for steels with low strain hardening exponent and effective yield strength, such as, G250 steel. It is also found that the fracture toughness of steel determined in accordance with different standards can be quite different, and the performance of the normalization method depends very much by the standard used, especially for steels with low strain hardening exponent and effective yield strength.