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用表面裂缝法在室温下研究了三种厚度(10,8,5mm)、三种宽度(B=8mm,W=110,80,56mm)的30CrMnSiA板材的断裂韧性。用最大载荷P_(max)计算断裂韧性,不易得到板材的K_(IE)值。如选用相对有效裂缝扩展Δα/α_0=10%和5%确定的“条件”载荷P_(10)和P_5计算,在P_(max)/P_(10)≤1.2和P_(max)/P_5≤1.3条件下,可较容易地得到K_(IE)和K_(IC)值。作K_R-Δα曲线。即是以K描述的阻力曲线。规定裂缝真正扩展Δα=2%α_0和7%α_0,相应的阻力各为K_(IC)和K_(IE)。它们与用“条件”载荷计算的K_(IC)和K_(IE)符合得很好。K_(IC)和J积分换算的K_(IC)值吻合,K_(IE)和P_(max)计算的有效K_(IE)值吻合。 K_(IC)和K_(IE)存在着近似的关系,为:K_(IC)=(0.85～0.90)K_(IE) 对试件尺寸要求: 板厚:B≥1.0(K_(IC)/σ_(0.2))~2或1.25(K_(IC)/σ_(0.2))~2;板宽:8≤W/B≤10,4≤W/2C≤5;有效长度:l≥2W。
The fracture toughness of 30CrMnSiA sheets with three thicknesses (10, 8, 5 mm) and three widths (B = 8 mm, W = 110, 80, 56 mm) were investigated by surface crack method at room temperature. With the maximum load P_ (max) calculated fracture toughness, difficult to get K_ (IE) plate value. If P_ (10) and P_5 of the “condition” load determined by the relative effective crack propagation Δα / α_0 = 10% and 5% ≤ 1.3, K_ (IE) and K_ (IC) values can be easily obtained. For K_R-Δα curve. It is the resistance curve described by K. It is stipulated that the crack truly expands Δα = 2% α_0 and 7% α_0, and the corresponding resistances are K_ (IC) and K_ (IE) respectively. They are in good agreement with the K_ (IC) and K_ (IE) calculated with the “condition” load. The K_ (IC) value of K_ (IC) and J integral agree well with the effective K_ (IE) value calculated by K_ (IE) and P_ (max). The approximate relationship between K_ (IC) and K_ (IE) is as follows: K_ (IC) = (0.85 ~ 0.90) K IE The size requirements of the test piece are as follows: Thickness: B≥1.0 (K_ (IC) (0.2)) ~ 2 or 1.25 (K_ (IC) / σ_ (0.2)) ~ 2; board width: 8≤W / B≤10,4≤W / 2C≤5; effective length: l≥2W.