高強度鋼材溶接継手のH_2SおよびCO_2ガス環境中における腐食疲労強度(<特集>フラクトグラフィ)

概要

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In order to clarify the influence of H_2S and CO_2 gas environments on the fatigue strength of high strength steel welded joint, corrosion fatigue tests of 17-4PH T type welded joint were carried out in {H_2S gas (5000ppm) + humid air (353K, 90% relative humidity)} and 99.9% CO_2 gas (353K, 90% relative humidity) environments by use of a corrosion fatigue testing apparatus in gaseous environment. The fatigue strength of 17-4PH T type welded joint at 2.0 × 10^7 cycles in {H_2S gas (5000ppm) + humid air (353K, 90% relative humidity)} and in 99.9% CO_2 gas (353K, 90% relative humidity) was 50 and 46 percent lower than that in air, respectively. The influence of H_2S gas content on fatigue life was remarkable in H_2S gas content ranging 50 to 5000ppm. In the humid H_2S and CO_2 gas environments corrosion pits were observed at the crack initiation area of the fracture surface. While striation was observed at the crack propagation area of the fracture surface. Thus, it is concluded that the initiation of corrosion pits at the crack initiation area is the major cause of the reduction in fatigue strength of 17-4PH T type welded joint in humid H_2S and CO_2 gas environment.
社団法人日本材料学会の論文
1997-06-15