鉴于断裂行为是建筑用钢的重要特征,从WGJ510C2热轧钢板上截取20 mm×40 mm×180 mm试样通过三点弯曲试验对其弹塑性断裂力学参数CTOD和J积分进行了测定和分析。结果表明,用CTOD法表征的阻力曲线为δR=0.787(0.123+Δa)0.685,用J积分法表征的阻力曲线为JR=461.2Δa0.435;高的δR值表明裂纹尖端的弹塑性储能也高,通过计算得出,在0 ℃时δc=0.187 mm,J0.2=229 kJ/m2;从其阻力变化的规律可以看出,用WGJ510C2钢具有优良的抗断裂能力。

A Mn-Mo-Nb (Ti,V) construction steel (WGJ510C2) has such properties as lower ratio of σs/σb (≤0.8),refractoriness,weather resistance and high heat input weld-ability. Its fracture behavior was investigated because of the most important usage in construction. The samples were cut from the hot rolled sheet with dimensions of 20 mm×40 mm×180 mm for examining the fracture toughness of the steel by means of three-point-bend test. The test was performed to get elastic-plastic fracture mechanical parameters (CTOD): δR (critical value of opening displacement of the rapture),Δa (propagation value of static rupture) and JR (crack propagation resistance). The crack propagation behaviors can be estimated from the analytic fracture model which show that the parameters have following regression relationship,i.e.,δR=0.787(0.123+Δa)0.685;or JR=461.2Δa0.435. The high value of δR indicated that the plastic store energy at crack tips is high. By calculating,δc＝0.187 mm,J0.2=229 kJ/m2 at 0 ℃. It can also be concluded that fracture resistance of the steel is excellent.