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The AISI 41B30H steel is one of the materials used to produce cylinders for storing natural gas for vehicles. These pressure vessels are normally produced by flow forming of a seamless tube of this material and followed by spinning process, a hot forming process that closes the ends of the tube. In this work, the mechanical properties of an AISI 41B30H steel heat-treated in the intercritical region, to produces a dual-phase microstructure of ferrite-martensite have been studied and compared with that of the material in the normalized as-received condition. The determination of quenching temperature within the intercritical region was obtained using computer simulation with THERMO CALC software and these results have been validated by metallographic analysis. The forming properties have been analyzed by means of tensile tests.

ISO 11439 standards consider 4 types of high-pressure cylinders to storing natural gas for vehicles applications. Among them the type 2, metal-lined hoop wrapped cylinder, is the aim of this work. It describes a numerical model built using ANSYS application to determine stress on the metal liner and on composite material applied on the liner by filament winding process. Using design criterion for laminate composites, the total thickness of the composite layer has been evaluated to get an optimized value. Employing the element shell multilayer of ANSYS 8.1 and a model of the type 2 cylinder, the stress state in the metal liner and in each layer of the composite has been studied.