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用表面裂纹法在室温下研究了三种厚度(10、8和5mm)、三种宽度(110、80和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。如选用相对有效裂纹扩展△α/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,可以得到K_(IE)和K_(IC)值。作K_R-△α曲线,即是以K描述的阻力曲线。规定裂纹真正扩展△α=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)还和J积分换算的K_(IC)值吻合,K_(IE)还和用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_(IE)/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 of three thicknesses (10, 8 and 5 mm) and three widths (110, 80 and 56 mm) were studied 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_ (10) ≤1.2 and P_ (max) / P_5≤1 and P_5 are calculated by using “conditional load” P_ (10) and P_5 determined by the relative effective crack propagation △ α / α_0 = 10% and 5% 1.3, K_ (IE) and K_ (IC) values can be obtained. For K_R- △ α curve, that is described in K resistance curve. Provisions crack real expansion △ α = 2% α_0 and 7% α_0, the corresponding resistance for the K_ (IC) and K_ (IE). They are in good agreement with K_ (IC) and K_ (IE) calculated with “conditional loading”. K_ (IC) also agrees well with the K_ (IC) value of J integral conversion, and K_ (IE) also agrees with the effective K_ (IE) value calculated with P_ (max). The approximate relationship between K_ (IC) and K_ (IE) is: K_ (IC) = (0.85 ~ 0.90) K_ (0.2)) ~ 2 [or 1.25 (K_ (IC) / σ_ (0.2)) ~ 2] plate width, 8≤W / B≤10,4≤W / 2c≤5 effective length,