STEEL MATERIAL FOR SEAT BELT TORSION BAR, MANUFACTURING METHOD OF STEEL MATERIAL FOR SEAT BELT TORSION BAR, AND SEAT BELT TORSION BAR COMPONENT

• Main Authors: CHIBA MASAMICHI, SAKATA MASAYUKI
• Format: Patent
• Language: English; Japanese
• Published: 10.10.2019
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

To provide a steel material for seat belt torsion bar capable of exhibiting high twisting characteristic and high initial torque even with general steel components.SOLUTION: There is provided a steel material for seat belt torsion bar containing C:0.03 to 0.25 mass%, Si:over 0 to 0.35 mass%, Mn:over 0 to 0.6 mass%, P:over 0 to 0.05 mass%, S:over 0 to 0.05 mass%, Al:0.005 to 0.2 mass% and the balance Fe with inevitable impurities, and having a metal structure containing ferrite and the balance having at least one of pearlite and spheroidal carbide, crystal grain size number of the ferrite of 8.5 or more, half width of X ray diffraction peak on a (211) surface of the ferrite of 0.90° or less.SELECTED DRAWING: None 【課題】一般的な鋼成分であっても、得られる部品において高い捻回特性と高い初期トルクを発揮することができるシートベルトトーションバー用鋼材を提供する。【解決手段】Ｃ：０．０３〜０．２５質量％、Ｓｉ：０超〜０．３５質量％、Ｍｎ：０超〜０．６質量％、Ｐ：０超〜０．０５質量％、Ｓ：０超〜０．０５質量％、及びＡｌ：０．００５〜０．２質量％、を含み、残部がＦｅ及び不可避的不純物からなり、金属組織が、フェライトを含み、残部がパーライト及び球状炭化物の少なくとも一方からなり、フェライトの結晶粒度番号が８．５番以上であり、フェライトの（２１１）面におけるＸ線回折ピークの半価幅が０．９０°以下である、シートベルトトーションバー用鋼材である。【選択図】なし