Patent ID: 7393421

Claim:
A process for thermal forming and quenching a tubular structure of heat treatable steel alloy to produce a molded structure characterized by a martensitic phase structure, the process comprising: (a) introducing a tubular member of heat treatable steel alloy into a shape-defining mold cavity; (b) heating the tubular member to a level above its softening point such that the steel alloy assumes a substantially austenitic phase structure; (c) molding the heated tubular member by introducing a molding gaseous fluid into the mold cavity wherein the molding gaseous fluid applies gas pressure against portions of the tubular member at the interior of the tubular member such that the tubular member is pushed outwardly to assume a shape substantially conforming with the mold cavity; and (d) quenching the molded tubular member to at least partially transform the austenitic phase structure to a martensitic phase structure by flowing a quenching gaseous fluid through the interior of the molded tubular member while the tubular member is held within the mold cavity with exterior surface portions of the molded tubular member held in contacting relation with the surface of the mold cavity.