黄銅の応力腐食割れに関する研究（第１報）－α黄銅の場合－

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Probability distribution of failure times and cracking times of stress corrosion cracking in Cu-35%Zn alloy (α brass) under constant stresses (80%, 60%, 50% or 40% of the yield stress) in Mattsson's solutions of pH 6.5, 7.0, 7.5 and 8.5 has been analysed by using the Weibull probability paper which is widely used reliability engineering. Probability distribution of failure times (Life) was found to be described as single or composite Weibull distribution, but in cracking times (Crack), as only single distribution. Median failure times and median cracking times of the distributions depend on the pH and the applied stress. A concave or pan shaped curves between the median failure times or cracking times and pH are observed at applied stress of 80% and 60% of the yield stress, which correspond to the result by Mattsson. The shape parameters observed in the ditributions of failure times and cracking times show between 1.6 and 3.6 in the pH range of 6.5-7.5 at any applied stress, but in the pH of 8.5, the values show larger than 3.6. Those shape parameters larger than unity indicate the wearout failure which seems to correspond to the crack propagation. In the range of pH 6.5-7.5, the crack propagation seems to be the type of intergranular cracking, and in the pH of 8 5, it seems to be the type of transgranular cracking.
1982-11-25