The Effect of Hydrogen on the Master Failure Curve of APL 5L Gas Pipe Steels (original) (raw)

Abstract

The effect of hydrogen on the material failure curves of APL 5L gas pipe steels was analysed from viewpoint of the notch fracture mechanics. The material failure curves based on two-parameter fracture criterion have been determined for API 5L X52, X70 and X100 gas pipe steels. The notch fracture toughness c K , and the effective T-stress were employed to describe the material failure curve. Tests were carried out on electrolytic hydrogen charged SENT, CT, RT (Roman Tile) and DCB specimens with a notch. Fracture initiation was detected by acoustic emission. Material failure curves for hydrogen charged steels and steels without hydrogen were constructed. It was shown that there is critical hydrogen concentration, which causes significant reduction of local fracture resistance of pipe steels. Procedia Engineering 10 (2011) 942-947 T , has been successfully used to quantify the constraints of notch tip fields for various proposed geometry and loading configurations [5]. We suggest extending the curve of c ef c T f K , , for different steels charging by hydrogen. The results of test for the different specimens geometries with the notch aspect ratio a/t = 0.5 are presented for the case of electrolytic hydrogen charging during 30 days and compared with the results of initial state of the steels. The experimental assessment points ( c ef c T K , , , ) for four specimen geometries (CT, SENT, RT and DCB) of APL X52 steel are summarized in Fig.3. These experimental assessment points allow c ef c T K , , ) based on notch fracture mechanics. Int J Fracture 2011; 167: 173-182.

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