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金属材料以铸代锻已在很多领域广泛采用。铸件具有加工量小,工艺简便、成本低廉等优点。在强度级别相同的条件下,铸钢的常规塑性、韧性(δ,Ψ,α_K)一般比锻钢要低。但从断裂力学观点看,对高强度或超高强度钢构件,由于加工,制造及使用过程中不可避免的会产生宏观缺陷,因此衡量含缺陷构件安全性和使用寿命的力学参量,应当是断裂韧性 K_(1c)和裂纹扩展速率 dα/dN。对铸钢来说,虽然常规塑性、韧性差,但这并不意味着其 K_(1c)和 dα/dN 也差。例如当σ_b为140公斤/毫米~2时,25SiMnCrMo 铸钢的 K_(1c)和 dα/dN 就比同强度的40CrNiMoA 锻钢要好。
Metal forging forging has been widely used in many fields. Casting with a small amount of processing, technology is simple, low cost and so on. Under the same strength level, cast steel generally has lower plasticity and toughness (δ, Ψ, α_K) than forged steel. However, from the point of view of fracture mechanics, macroscopic defects inevitably arise in the machining of high-strength or ultra-high-strength steel parts due to the processing, manufacturing and use. Therefore, the mechanical parameters for measuring the safety and service life of defective parts should be fracture Toughness K_ (1c) and crack growth rate dα / dN. For cast steel, although the conventional plastic, toughness, poor, but it does not mean K_ (1c) and dα / dN also poor. For example, when σ_b is 140 kg / mm ~ 2, K_ (1c) and dα / dN of 25SiMnCrMo cast steel are better than that of 40CrNiMoA steel with the same strength.