应用单试样规则化法完成了压力容器用钢SA-508紧凑拉伸(Compact tension，CT)、三点弯曲(Single edge-notched bending，SEB)和小尺寸含内侧边裂纹C形拉伸(C-shaped inside edge-notched tension，CIET)三类试样的延性裂纹扩展行为试验，获得了J-Δa阻力曲线。结果表明，SA-508钢的J-Δa阻力曲线受试样构形和裂纹尺寸的影响较大，其根本原因在于试样裂纹尖端约束不同而引起延性断裂行为差异。引入J-Q-M三参数约束理论考察断裂试样的裂尖约束效应，采用权重平均法求解与距离无关的约束参数Q。弹塑性有限元分析结果表明，平面应变条件下的Q参数与载荷水平无关，但三维条件下的Q参数却仍受载荷水平的影响。基于J-Q-M三参数约束方法，建立三类试样满足J-Q-M控制的有效尺寸条件。进一步地，结合条件启裂韧度J_0.2BL、J_0.5BL试验结果和J-Q-M理论，获得了基于Q参数的约束修正J-Δa阻力曲线簇，可用于任意约束试样以及实际含裂纹结构的延性断裂行为预测。

Experiments on compact tension(CT),single edge-notched bending(SEB) and C-shaped inside edge-notched tension(CIET) specimens for pressure vessel steel SA-508 by using normalization method are carried out. The resultedJ-Δacurves are affected by specimen configurations and crack sizes,which is essentially owing to the different crack front constraint effect of specimen.J-Q-Mthree-parameter theory is introduced to qualify the crack front constraint effect,and weight average method is applied to solve the distance-independent constraint parameterQ. Finite element analyses show that,the parameterQ is load-independent under plane strain condition,but it is still influenced by load level under 3D condition. The size requirements ofJ-Q-Mdominance for three types of specimens have been constructed. Furthermore,by combining the experimental conditional critical toughnessesJ_0.2BL, J_0.5BL andJ-Q-Mapproach,the constraint-correctedJ-resistance curves are established based on the parameterQ,these curves can be applied to predict the ductile fracture behavior for any specimen and actual flawed structures.