Abstract: A process for manufacturing a containment device including: providing steel slab including (in wt. %) C: 0.05%-0.4%; Si: ?2.0%; Mn: ?2.0%; P: ?0.1%; N: ?200 ppm; remainder iron and inevitable impurities; hot rolling the slab to steel strip after reheating the slab, or utilizing the casting heat by hot-charging the slab, or by direct rolling the slab after casting, followed by cooling the strip to coiling temperature and coiling; cold rolling the strip at between 40 and 95% thickness reduction to form cold-rolled strip; continuous annealing by reheating to temperature above Ac1, homogenising at least 5 seconds, followed by rapid cooling; producing the device. The device has steel at least 10 vol. % martensite and/or bainite and reduced properties of anisotropy. Containment device manufactured by the process and producing isolation barrier material for high temperature and/or pressure sealing for containment devices are also disclosed.