The effect of hydrogen-induced cracking on the integrity of steel-components

Abstract

The occurrence of hydrogen embrittlement is a much researched phenomenon, known to cause mechanical property degradation and catastrophic failures. The ductility loss brought about by hydrogen ingress is encountered even in unstressed bodies where such cracking is termed hydrogen induced cracking (HIC) and is in phenomenological contrast to catastrophic failures encountered by stressed bodies subjected to hydrogen producing environments. This article will discuss HIC in some detail. This form of cracking is especially detrimental and often observed in oil country tubular goods (OCTG) which are subjected to sour gas. Consequently, the significance of MLC is most appreciated by oil companies at various stages of oil extraction, transportation and storage. In this article the chemical and metallurgical genesis of HIC, its harmful impact on material and component integrity are discussed. It has been noted that MnS inclusions are extremely harmful to this form of cracking. Similarly, centreline segregation in the ingot stage and deoxidation practices during steelmaking were found to affect HIC. Some case studies of HIC obtained from literature are presented. The variables affecting the propensity to HIC are provided in brief. Suitable measures to reduce or eliminate HIC in steels are also discussed.