This paper investigates the relationship between J-integral and crack tip opening displacement, $delta$$_{t}$ using Gordens results of numerical analysis. Estimation were carried out for several strength levels such as ultimate, flow, yield, ultimate-flow, flow-yield stress to determine the influence of strain hardening and the ratio of crack length to width on the J-$delta$$_{t}$ relationship. It was found that for SE(B) specimens, the J-$delta$$_{t}$ relationship can be applied to relate J to $delta$$_{t}$ as follows J= $m_{j}$$ imes$$sigma$$_{i}$$ imes$$delta$$_{t}$ where $m_{j}$=1.27773+0.8307($alpha$/W), $sigma$$_{i}$ : $sigma$$_{U}$, $sigma$$_{U-F}$=1/2 ($sigma$$_{U}$+$sigma$$_{F}$), $sigma$$_{F}$, $sigma$$_{F-Y}$=Y=($sigma$$_{F}$+$sigma_{Y}$), $sigma_{Y}$