STRESS CORROSION OF HIGH STRENGTH STEELS IN WATER MEDIUM
Chu Wuyang;Li Shiqiong;Xiao Jimei (Hsiao Chi-mei);Wang Cheng Beijing Institute of Iron and Steel Technology
Cite this article:
Chu Wuyang;Li Shiqiong;Xiao Jimei (Hsiao Chi-mei);Wang Cheng Beijing Institute of Iron and Steel Technology. STRESS CORROSION OF HIGH STRENGTH STEELS IN WATER MEDIUM. Acta Metall Sin, 1980, 16(2): 179-259.
Abstract A review was made of the modified WOL-type constant displacement speci-men for stress corrosion by which the _(Iscc) and da/dt of four high strength steels,as 30CrMnSiNi_2A, 40CrNiMoA, 30CrMnSiA and ZG-18 cast steel, in water me-dium were evaluated. Among these steels, the influence of heat treatment, thestrength and microstructure of 0CrMnSiNi_2 A on the K_(Iscc) and da/dt has beenstudied in detail. The K_(Iscc) obtained may be increased with decrease f heir ownstrength of specimens undergone same heat treatment. while the K_(Iscc) of specimens,which were isothermal uenched and tempered for structure of equal strength,may be much higher than specimens with both martensite and on-temperedbainite structures. The growth and extension of cracks may be changed whenthe tensile strength of steels σb=130-140 kgf/mm~2, in consequence, the K_(Iscc)increases markedly and da/dt decreases to greater extent. The threshold alues of stress corrosion cracking K_(Iscc)(ρ) was measured bymodified WOL-type notched specimens of various tip radius as follow:K_(Iscc)(ρ)={B ρ≤ρ_0 Aρ~(1/2) ρ>ρ_0where A and B are material constants. For ultra-high strength steel 0CrMnSiNi_2A, A=4170MPa, B=22MPa·m~(1/2) and ρ_0=1.027mm. This correlation conformsto theoretical treatment. According o the experimental results, the accidental failures of the fasteningscrew made of ultra-high strength steel 30CrMnSiNi_2 ere quantitatively ana-lyzed by linear elastic fracture mechanics. Therefore, the remedy to prevent thefailure of astening screw has been suggested.
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