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利用示波冲击试验,对高强度30CrNiMnMoB 钢的脆断机理进行了研究。根据示波冲击的载荷—挠度曲线可得出 P_f—T和 P_(gy)—T曲线,由此计算出材料的本征性能——微观解理断裂应力(σ_f~*)。由 Griffith 断裂公式σ_f~*=[4E(γ_s+γ_p)/π(1-v~2)x]~(1/2),讨论控制裂纹失稳扩展的微观组织因素。结果表明,试验钢的σ_f~*随强度升高而增大,控制高强度钢裂纹失稳扩展的微观因素是马氏体板条束。
Using the oscillometric impact test, the brittle fracture mechanism of high strength 30CrNiMnMoB steel was studied. The P_f-T and P_ (gy) -T curves can be obtained according to the load-deflection curve of the oscillometric impact, and the intrinsic properties of the material - the micro-cleavage fracture stress (σ_f ~ *) can be calculated. From the Griffith fracture formula σ_f ~ * = [4E (γ_s + γ_p) / π (1-v ~ 2) x] ~ (1/2), the microstructural factors that control the instability of the crack propagation are discussed. The results show that the σ_f ~ * of the test steel increases with the increase of strength, and the microscopic factor that controls the instability propagation of the crack of the high strength steel is martensite lath.