METHOD FOR MANUFACTURING MACHINE STRUCTURAL MEMBER

• Main Authors: KAWASAKI KAZUHIRO, FUKAZAWA KENGO, MISAKA YOSHITAKA
• Format: Patent
• Language: English
• Published: 04.11.2011
• 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

PROBLEM TO BE SOLVED: To provide a method for manufacturing a machine structural member with which workability can be made to be satisfactory even if a steel raw material for improving the temper softening resistance is used.SOLUTION: This method includes; a step, in which the steel raw material composed by mass% of 0.3-1.5% C, 0.2-2.0% Mn and one or more kinds intentionally selected from the group of 0.5-2.0% Si, 0.1-1.5% Cr, 0.1-1.5% Mo, 0.05-0.5% V and 0.005-0.2% Nb, and the balance Fe with inevitable impurities, is softening-treated to make the metallographic structure composed of the ferrite having ≥30% area ratio and the pearite, or the metallographic structure composed of the ferrite and the spheroidal carbide or the metallographic structure composed of the ferrite and the granular carbide; a step for work-treating the softening-treated steel raw material into a prescribed shape; and a step, in which at least two times of high frequency-induction heat-treatment are performed to the work-treated steel raw material and the metallographic structure on the surface layer is made to the martensite and the metallographic structure in the intermediate layer adjoined to the surface layer is made to a tempered-martensite or a tempered-martensite, ferrite and pearite.