号数 ばね論文集40号(1995年)
ページ数 pp.57ー102
種類 共同研究報告
論文名 弁ばね用高強度Si‐Cr鋼オイルテンパー線の研究
Title Studies on High-Strength Oil-Tempered Chromium-Silicon Alloy Steel Wire for Valve Springs
著者 ばね技術研究会
Author Valve Spring Working Group Research Committee on Durability of High-Strength Steel Wire
抄録 弁ばね用材料の高強度化(ここでは引張強さの高いことを高強度と呼ぶ。)に伴って,加工性及び耐へたり性の低下が懸念され,耐疲労性についても,単純に向上を期待できないため,本委員会では化学成分,線の引張強さ,低温焼なまし温度,ショットピーニングによる圧縮残留応力などが線及びばねの諸特性に及ぼす影響について調査・研究を行った。すなわち,従来のJIS G 3566に定めるのオイルテンパー線(引張強さ1900,2000MPa)と,炭素量を規格の上限まで増量し,バナジウムを添加し,引張強さを2000, 2100MPaに調質した高強度鋼オイルテンパー線を用意し,上述の諸要因の影響を比較した。その結果,供試高強度鋼線はJIS規格の比較鋼線に比べて加工性は同等,耐久性は大幅に向上,耐へたり性は同等以上であり,その優位性が確かめられた。また,高強度鋼線の耐久性や耐へたり性をさらに向上させるには,単なる素線の高強度化ではなく,化学成分の変更や低温焼なまし条件の適正化,さらにショットピーニングなどの表面処理技術の改善が従来以上に重要なことがわかった。
Abstract

It is afraid that increasing the strength of oil-tempered steel wire for valve springs might result in a loss of workability, fatigue strength and creep resistance. The committee, therefore, investigated the effects of the chemical composition, wire strength, annealing condition, residual stress induced by shot peening, etc., on the mechanical properties of wires and valve springs.
The material used for this study was made of the conventional oil-tempered high tension steel wire (JIS G 3566) by increasing its carbon level to the JIS-prescribed upper limit and adding some vanadium. It was then made into two specimens by tempering to tensile strength levels of 2,000 and 2,100MPa, respectively. For the purpose of comparison, two other specimens were made of conventional oil-tempered wire (JIS G 3566) by tempering to strength levels of 1,900 and 2,000MPa, respectively.
In conclusion, high-tension steel wire of this study has been found to possess equal workability with improved fatigue strength, and better creep resistance, when compared with the standard steel wire (JIS G 3566), thus demonstrating the superiority of high-tension steel wire for valve springs. To further improve fatigue strength and creep resistance, it has been found more important to make changes in chemical compositions, and to make further improvements in shot peering process and in other surface-treating technologies, rather than only increasing the tensile strength of the wire.

著者の所属  
Belonging  
Key Words Oil-tempered wire, Valve spring, Fatigue strength, Creep resistance, Workability, Annealing, Shot peening