ラインパイプ用鋼の応力腐食割れ感受性に及ぼす材料因子の影響

概要

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Material factors that might influence the susceptibility of buried line pipe steels to stress corrosion cracking (SCC) were studied by means of the slow strain rate technique (SSRT) of SCC tests in carbonate-bi-carbonate (CO_3) and caustic alkali (OH) solutions which had been identified as the environments that could produce SCC on buried steel pipelines. The results obtained are summarized as follows : 1) Possible SCC potential ranges for as-received line pipe steels in OH and CO_3 were -880 to -1230mV and -650 to -875mV vs. Cu-CuSO_4, respectively, and were independent of types of steel. 2) SCC susceptibility of every line pipe steel changed in a decreasing order of STPY 41>X42>X65CR>X60CR>X65QT. 3) Effect of rolling direction on the SCC susceptibility was weld metal>C>L for STPY 41, while C>L>weld metal for the rests, both in a decreasing order of susceptibility. 4) Effect of heat treatment on the SCC susceptibility was water quenched>annealed>as-received>quenched and tempered, in a decreasing order of susceptibility. 5) Activation energies for the growth of stress corrosion cracks in CO_3 and OH were almost the same with those of crack-tip dissolution, which lended strong support to the suggestion that the controlling process in SCC of line pipe steels in CO_3 and OH was crack-tip dissolution.
社団法人日本鉄鋼協会の論文
1983-09-01