X65QS抗腐蝕管線用無縫鋼管應(yīng)力腐蝕開裂斷口分析

Analysis on Fracture of Sulfide Stress Corrosion Crack of X65QS Anti-corrosion Seamless Steel Linepipe

摘要: 對(duì)X65QS抗腐蝕管線用無縫鋼管進(jìn)行NACE標(biāo)準(zhǔn)A法腐蝕試驗(yàn)，采用金相顯微鏡、掃描電鏡觀察應(yīng)力腐蝕開裂斷口的形貌，分析應(yīng)力腐蝕開裂的原因。分析認(rèn)為：開裂斷口近邊緣部分存在D類夾雜物，氫在夾雜物處聚集，并成為應(yīng)力集中源和裂紋開裂源，在氫和應(yīng)力的共同作用下，在夾雜缺陷部位形成氫脆缺陷，造成缺陷部位基體脆化，減少了試樣有效受力面積，導(dǎo)致裂紋快速擴(kuò)展和試樣的早期斷裂。

Abstract: The corrosion test is conducted to the X65QS anti-corrosion linepipe as per NACE Method A.And the morphology of the fracture of the SCC crack is observed by means of the metallographic microscope and the SEM to find out the cause for the said crack.It is identified via the analysis that there exist Class D inclusions on the fringe of the fracture;hydrogen is acuminated in the inclusion area,forming the stress gathering and the cracking origins;under the co-effect by both hydrogen and the stress,the hydrogen brittle defect is developed in the inclusion defective part,and thus leads to embrittlement of the base metal in the defect part.As a result,the effective stressed area of the specimen is reduced,resulting in fast crack expansion and early-stage fracture of the specimen.