EVALUATION OF MECHANICAL PROPERTIES OF THE AISI 41B30H STEEL WITH THE CHANGING OF THE VOLUME FRACTION OF FERRITE AND MARTENSITE PHASES BY MEANS DIFFERENT HEAT TREATMENT TEMPERATURES IN THE INTERCRITICAL REGION.

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. The results indicate that the performance of the heat-treated dual-phase 41B30H steel in forming operation will be better than the as-received normalized material and encourages further research work to show whether advantages could be taken from intercritical heat-treatment in flow forming process by the industrial plant.