论文部分内容阅读
本文对应力腐蚀试验的WoL型恒位移试样作了评述。并用它测最了四种高强度钢(30CrMnSiNi_2 A、30CrMnSiA、40CrNiMo、ZG-18铸钢)在水介质中的止裂K_(ISCC)以及da/dt。对其中的30CrMnSiNi_2A钢研究了热处理工艺对K_(ISCC)、da/dt的影响,同时探讨了强度和组织的作用。结果表明,对同一类处理,随强度下降K_(ISCC)提高。在相同强度时,等温后回火组织的K_(ISCC)明显比马氏体组织和不回火贝氏体组织高得多。当强度σ_b≤130～140公斤/毫米~2时,裂纹扩展特征发生了变化,da/dt也大幅度下降。当σ_b<110公斤毫米~2时在水介质中不再产生应力腐蚀裂纹。 我们用不同曲率(ρ)的恒位移缺口试样(B=20mm)测量了缺口形成应力腐蚀裂纹的界限应力强度因子K_(ISCC)(ρ),结果表明A是材料常数。对σ_b=160公斤/毫米~2的30CrMnSiNi_2A钢,A=426公斤/毫米、σ_b=140公斤/毫米~2的30CrMnSiA以及40CrNiMo钢的A值更高。 根据实验数据,运用线弹性断裂力学对30CrMnSiNi_2A钢(σ_b=160公斤/毫米~2)螺桩的应力腐蚀断裂进行了定量分析,并提出了提高螺桩安全性的具体办法。
In this paper, the stress corrosion test WoL type constant displacement specimens were reviewed. The crack arrest K_ (ISCC) and da / dt of four high strength steels (30CrMnSiNi_2A, 30CrMnSiA, 40CrNiMo and ZG-18 cast steel) in aqueous media were measured. The effects of heat treatment on K_ (ISCC) and da / dt of 30CrMnSiNi_2A steel were studied, and the effects of strength and microstructure were discussed. The results show that for the same type of treatment, K_ (ISCC) increases with decreasing intensity. At the same intensity, the K_ (ISCC) of isothermal tempered tissue was significantly higher than that of martensite and non-tempered bainite. When the strength of σ_b≤130 ~ 140 kg / mm ~ 2, the crack propagation characteristics have changed, da / dt also dropped significantly. When σ_b <110 kg mm ~ 2 stress corrosion cracking no longer occurs in the aqueous medium. We used the constant displacement notched specimens (B = 20mm) with different curvature (ρ) to measure the critical stress intensity factor K_ (ISCC) (ρ) of the notch forming stress corrosion cracking. The results show that A is the material constant. The values of A for 30CrMnSiNi2A steel with σ_b = 160 kg / mm ~ 2, A = 426 kg / mm and 30CrMnSiA with σ_b = 140 kg / mm ~ 2 and 40CrNiMo steel are higher. Based on the experimental data, the stress corrosion cracking of 30CrMnSiNi_2A steel (σ_b = 160 kg / mm ~ 2) screw piles was quantitatively analyzed by using linear elastic fracture mechanics and the concrete methods to improve the safety of screw piles were proposed.