Hydrogen-induced cracking and healing behaviour of X70 steel

JOURNAL OF ALLOYS AND COMPOUNDS

卷:484

Article

Dong, C. F.¹  Li, X. G.¹  Liu, Z. Y.¹  Zhang, Y. R.¹ 

[1] Univ Sci & Technol Beijing, Ctr Corros & Protect, Minist Educ, Key Lab Corros & Protect, Beijing 100080, Peoples R China

关键词: X70 pipeline steel;    Hydrogen-induced cracking;    Crack healing;    Hydrogen permeation;   

DOI  :  10.1016/j.jallcom.2009.05.085

来源: Elsevier

【 摘 要 】

In this paper, the electrochemical hydrogen charging for X70 pipeline steel in H2SO4 solution was carried out and the influence of non-metallic inclusions and microstructure on the hydrogen-induced cracking (HIC) and healing behavior of X70 pipeline steel was investigated by SEM and TEM technique. Based on the results of hydrogen permeation tests, the diffusivity of hydrogen at room temperature and the density of hydrogen trapping sites in X70 steel were estimated. Heat treatment was used to heal the hydrogen-induced cracks in X70. It was found that non-metallic inclusions, such as nitrides and oxides, played different roles on HIC of X70 steel. Oxides are more sensitive than nitrides to HIC in X70 steel. Cracks initiated and grew preferentially along the grain boundary of polygonal ferrite instead of the acicular ferrite when the sample was charged of enough hydrogen. It also demonstrated that proper heat treatment can heal such cracks. The healing process was divided into two steps: firstly, many cracks dissociated into several detached segments; secondly, theses segments regressed into spherical voids. The mechanism of crack healing was also discussed. (C) 2009 Elsevier B.V. All rights reserved.

【 授权许可】

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