HIGH-FREQUENCY DEEP HARDENING METHOD OF LARGE-SIZED CAST IRON TOOTH-SHAPED MEMBER

摘要

PURPOSE:To improve the toughness, impact resistance and wear resistance over the entire part of a tooth-shaped member for construction machinery by casting said member of a spheroidal graphite cast iron contg. a specific ratio of Mn and subjecting the member to a deep part hardening treatment under specific conditions. CONSTITUTION:The large-sized tooth-shaped member for construction machinery to be used for excavating, crushing, etc., is cast of the spheroidalgraphite cast iron contg. 0.60-2.00wt% Mn. The tooth-shaped member is subjected to =1 passes of quick heating and heating stoppage by a high-frequency induction heater so as to attain approximately 850 deg.C surface temp. according to the thickness of the member. The heat of the quick surface heating is driven deep into the core part of the member to heat the core part up to about 850 deg.C and in addition, the 2nd stage of heating for the purpose of hardening is executed quickly up to about 900 deg.C and the member is quench-hardened by a prescribed coolant. The quench hardened part is formed down to 30-40mm depth from the surface of the tooth-shaped member and the tooth-shaped member having the excellent wear resistance and strength and good durability is produced.