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題名 | 不同合金元素添加及加速冷卻製程對管線用鋼之耐蝕性行為影響(2):硫化物應力腐蝕破裂= |
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作者 | 廖啟民; 劉宏義; |
期刊 | 材料科學 |
出版日期 | 19910600 |
卷期 | 23:2 1991.06[民80.06] |
頁次 | 頁135-145 |
分類號 | 440.365 |
語文 | chi |
關鍵詞 | 合金元素; 添加; 加速冷卻; 製程; 管線用鋼; 耐蝕性行為; 硫化物; 應力腐蝕; 破裂; |
中文摘要 | 不同Nb含量,以及Cu和Ni之添加對APIX60油管用鋼於含飽和H�特之 NACE水溶液中的硫化物應力腐蝕破裂(SSCC)行為,以及不同速率之加速冷卻對 於SSCC敏感性之效應,是本研究的重點。此外亦藉電化學極化曲線探討上述因 素對此鋼材在相同溶液中的均勻腐蝕性質的影響。 電化學試驗結果顯示,加速冷卻對非含鈮鋼的均勻腐蝕性質沒有影響,但對含鈮 鋼材則有效應。Cu之添加可少許改善APTX60鋼的抗均勻腐蝕性,而Ni的添加與 否則不影響加銅鋼的均勻腐蝕行為。 施力50降伏強度的定應力試驗結果顯示,隨Nb含量漸增,SSCC敏感性提高;0.29Cu 之添加則無明顯效應;而添加0.31死的Ni則有害SSCC性質。此外,控制軋延後隨 冷卻速率之提升,雖可提高材質之機械強度,但卻因強度之提高而使得其抗SSCC 性質自然變差;然而,對相同強度之鋼材而言,以加速冷卻產製之鋼材則比非加 速冷卻鋼具有較佳的抗SSCC性質。 破斷面和橫截面觀察顯示裂縫沿波來鐵帶生長,且其位置與MnS位置一致,因此 裂縫是在MnS和底材之界面上起始並生長。此外,橫截面中同時發現有垂直及平 行於應力方向的裂縫存在,因此SSCC乃是由SCC和HIC之共同作用所造成。 |
英文摘要 | The sulfide stress corrosion cracking (SSCC) behaviors of API X60 steels with various Nb, Cu,and Ni additons and different cooling rates after control rolling have been studied. The general corrosionbehaviors of these steels were also investigated with electrochemical polarization curves. The results of electrochemical tests show that general corrosion behaviors of steels without Nb arenot influenced by accelerated cooling control (ACC) process. But there are some effects of ACC processon that behaviors of Nb-addition steels. The addition of 0.29 Cu can slightly improve the general corrosion resistance of API X60 steels. However, the addition of 0.31 Ni in Cu-bearing steel has no effecton that behavior. Results of constant load testing in which specimens were loaded by 50 yield strength show thatSSCC resistance increases with increasing Nb content. The 0.29 Cu addition has no significant effect on the SSCC resistance but the sensitivity to this cracking is increased by 0.31 Ni addition. ACC process can increase the strength but decrease the SSCC resistances of the steel. However,with a similar strength, the SSCC resistance of ACC steels are better than that of non-ACC steels. Metallographic observations indicate that cracks propagate along pearlite band, and the positionsof cracks are coincident with those of MnS. This demonstrates that cracks initiate from and propagatealong the interfaces of MnS and matrix. Both the cracks perpendicular or parallel to the stress directioncan be observed simultaneously on the cross sections of specimens after testing. It suggests that SSCCbehavior is a combined effect of SCC and HIC. |
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