PURPOSE: To improve abrasion resistance as an excavation tooth by melting and forming steel having the prescribed composition into a tooth shape and, then, hardening and tempering the steel within the prescribed temperature zone.
CONSTITUTION: A steel material containing each of elements such as C, Si, Mn, P, S, Ni, Cr, Mo, B, V, and Nb within the range of the prescribed weight percentage is used as the material of an excavation tooth 1 plugged into an adapter 3 mounted on a bucket 3 and secured with a lock pin 4. The steel material having such a composition is melted and formed into the prescribed shape as the tooth 1 and, then, subjected to thermal treatment within the zone of temperature including 900 to 1000°C hardening treatment and 300 to 600°C tempering treatment. Also, material hardness can be enhanced by using such a material as having Vickers hardness kept between 550 and 700, and further having a mixed composition where a complex carbide mainly composed of Nb is precipitated into a matrix of tempered martensite, thereby contributing to the wear resistance of an excavation tooth member.
TAKAYASU HIROSHI
NAKAMURA SHIGEYOSHI
ONO TOSHIHIRO
HITACHI CONSTRUCTION MACHINERY