Effective Process Design for the Production of HIC-Resistant Linepipe Steels
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JMEPEG (2013) 22:2493–2499 DOI: 10.1007/s11665-013-0544-9
Effective Process Design for the Production of HIC-Resistant Linepipe Steels J. Nieto, T. Elı´as, G. Lo´pez, G. Campos, F. Lo´pez, R. Garcia, and Amar K. De (Submitted May 30, 2012; in revised form March 22, 2013; published online April 11, 2013) Production of slabs for sour service applications requires stringent control in slab internal quality and secondary processing so as to guarantee resistance against hydrogen-induced cracking (HIC). ArcelorMittal Steelmaking facility at Lazaro Cardenas, Mexico had recently implemented key steelmaking and casting processing technologies for production of sound, centerline free slabs for catering to the growing API Linepipe and off-shore market for sour service applications. State-of-the-art steelmaking with use of residual-free Direct-reduced Iron and continuous casting facilities with dynamic soft reduction were introduced for the production of slabs with ultra clean centerline. Introduction of controlled cooling of slabs for atomic hydrogen control well below 2 ppm has enabled production of slabs suitable for excellent HICresistant plate processing. Substantial tonnages of slabs were produced for production of API X52-X65 grade plates and pipes for sour service. Stringent quality control at each stage of steelmaking, casting, and slab inspection ensured slabs with excellent internal quality suitable for HIC resistance to be guaranteed in final product (Plates & Pipes). Details of production steps which resulted in successful HIC-resistant slab production have been described in this article.
Keywords
centerline segregation, direct-reduced iron, HIC, linepipe steel, soft reduction
1. Introduction Pipelines transporting sour gas containing (H2S) crude oil or gas are susceptible to hydrogen absorption at the inner surface of the pipe because of the anodic dissolution reaction of the type Fe fi Fe+2 + 2e, H+ + e fi H (Ref 1). The atomic hydrogen diffuses through interstices of iron and recombines as molecular hydrogen at free surfaces either at the pipe surface or internally at free surface provided by discontinuities within steel matrix such as inclusions, cavities, etc. (Ref 1, 2). The hydrogen gas accumulated inside the steel matrix may eventually be of several atmospheric pressures as the source can be inexhaustible and lead to hairline cracks, delayed cleavage fracture, etc. (Ref 2, 3). Pipelines for sour service, therefore, are subjected to critical qualification tests such as hydrogeninduced cracking (HIC), and sulfide stress corrosion cracking (SSCC) that evaluate resistance to hydrogen-induced cracking in a simulated severe sour service condition. Well-known sinks for hydrogen in steel are matrix-inclusion (mainly elongated MnS) interface, centerline segregation, and shrinkage cavities. MnS inclusions if not shape-controlled gets
This paper is based on AIST 2013 Richard J Fruehan Award for Best Paper. J. Nieto, T. Elı´as, G. Lo´pez, G. Campos, F. Lo´pez, and R. Garcia, ArcelorMittal La´zaro Ca´rdenas, 26113 La
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