The present study aims at charactering the crack growth resistance parameter in an 1 mm thick interstitial-free (IF) steel sheet using the energy dissipation rate parameter, $R$. The $R$-$\mathrm{\Delta }a$ plots of single-edge and double-edge notched tension specimens have been determined with only additional computations of mechanical and optical test data already generated in the course of determining the variation of crack tip opening angle with $\mathrm{\Delta }a$ following the optical method of ASTM E 2472. A new method has been adopted for determining the stationary value of energy dissipation rate, $R_{\infty }$, This has been done by analyzing mechanical test data generated in the course of essential work fracture (EWF) testing, with additional inputs on crack initiation points identified in those EWF tests. An attempt has been made to normalize the $R$-$\mathrm{\Delta }a$ plots in order to reduce the specimen geometry dependence of the energy dissipation results.

本研究旨在利用能量耗散率参数表征1 mm厚无间隙（IF）钢板的抗裂纹扩展参数， $\mathrm{[R}$。这$\mathrm{[R}$--$\mathrm{\Delta }\mathrm{一种}$ 在确定裂纹尖端张开角变化的过程中，仅通过已经生成的机械和光学测试数据的额外计算，即可确定单边缘和双边缘缺口拉伸试样的曲线图。 $\mathrm{\Delta }\mathrm{一种}$ 遵循ASTM E 2472的光学方法。采用了一种新方法来确定能量耗散率的固定值， ${\mathrm{[R}}_{\infty }$通过分析在基本工作断裂（EWF）测试过程中生成的机械测试数据，以及在那些EWF测试中确定的裂纹起始点的额外输入，可以完成此任务。试图规范化$\mathrm{[R}$--$\mathrm{\Delta }\mathrm{一种}$ 为了减少样品几何形状对能量耗散结果的依赖性。