STEEL MATERIAL, PROCESS FOR PRODUCING STEEL MATERIAL, AND APPARATUS FOR PRODUCING STEEL MATERIAL

• Main Authors: ICHIBA, MIKIYUKI, HIRAKAMI, DAISUKE, UEKI, YOSHIHARU, OKAMURA, TSUKASA, IWANAGA, KENGO, WATANABE, OSAMU, KODAMA, JUN-ICHI
• Format: Patent
• Language: English; French; Japanese
• Published: 08.10.2009
• Subjects: ALLOYS; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TREATMENT OF ALLOYS OR NON-FERROUS METALS

A process for producing a steel material is provided which includes subjecting a highly strengthened steel material (W) to a heat treatment to thereby cause part of the steel material to have a lower hardness than the remainder of the steel material (W).  The heat treatment comprises: a heating step in which that part of the steel material (W) which ranges from the surface to a certain depth is rapidly heated by induction heating or direct ohmic heating; and a cooling step in which the steel material (W) which has undergone the heating step is rapidly cooled at a given time period after the heating step.  In the heating step, the steel material (W) is heated to a temperature not lower than transformation point Ac1. L'invention concerne un procédé de production de matériau d'acier, qui consiste notamment à soumettre un matériau d'acier hautement renforcé (W) à un traitement thermique pour conférer à une partie du matériau d'acier une dureté moindre que le restant du matériau d'acier (W). Le traitement thermique consiste: en une étape de chauffage au cours de laquelle ladite partie du matériau d'acier (W), qui s'étend de la surface jusqu'à une certaine profondeur, est chauffée rapidement par induction ou par chauffage ohmique direct; et une étape de refroidissement au cours de laquelle le matériau d'acier (W), qui a subi l'étape de chauffage, est rapidement refroidi un certain temps après l'étape de chauffage. Lors de l'étape de chauffage, le matériau d'acier (W) est chauffé à une température qui n'est pas inférieure au point de transformation Ac1.