To provide a high strength and high toughness link chain in which the high strengthening of the link chain and the improvement of the delayed breakage resistance of the link chain for preventing unexpected breakage under a special atmosphere or an outdoor atmosphere, can be obtained and furthermore brittleness breakage under a low temperature atmosphere such as a cold district can be prevented, and to provide a manufacturing method of the link chain.
The high strength and high toughness link chain is composed a mass% of 0.15-0.8% C, 0.2-2.0% Si, 0.6-2.5% Mn, 0-0.005% Al, ≤0.05% P, ≤0.05% S, 0.4-2.0% Cr, ≤0.5% Mo, 0.0005-0.005% B and balance Fe with inevitable impurities, contains, in steel as a steel structure by vol.%, 5-15% retained austenite, ≤10% bainitic ferrite and polygonal ferrite, and ≥90% carbon concentration-treated martensite, and has a ≥80 J/cm2 dynamic toughness value and a ≥120 MPa-m1/2 static toughness value.
SUGIMOTO KOICHI
KOBAYASHI JUNYA
INA DAIKI
UNIV SHINSHU
Takashi Ishida
Tetsuji Koga
Hiroshi Kamematsu
Nakamura Asayuki
Nagasaka Tomoyasu