Abstract: In view of low constraint properties, single edged notched tension(SENT) specimens are gradually applied for the assessment on fracture toughness of pipe materials. Detailed analyses for the stress intensity factor, incremental plastic work and plastic factor used in the J-integral computation are conducted. The precision and validity are confirmed through the comparison between formulas obtained and references. Systematic investigation on the estimation of J resistance curves for SENT specimens is carried out on the basis of normalization method which concludes in the non-dimensional load separation method. The establishment of the load separation for SENT specimen is verified by finite element analysis. 30Cr2Ni4MoV used for steam turbine low pressure rotors, T92 pipe steel and 5083-H112 aluminum alloy are employed to experimentally complete the estimation of J resistance curves of SENT specimens by using the normalization method of non-dimensional load separation and reasonable fracture toughness values are acquired.

Key words: fracture toughness;J resistance curves;single edged notched tension(SENT) specimen;non-dimensional load separa-tion;normalization method