Patent ID: 8322253
Filing Date: 2012-12-04
Classification: B26B

Abstract:
1. A method of manufacturing a utility knife blade comprising: heating and quenching a coil of strip steel material comprising at least about 0.9% carbon to harden the strip steel material and to form a martensitic microstructure substantially throughout the coil of strip steel material; tempering the hardened strip steel material by reheating the hardened strip steel material to form a tempered martensitic microstructure substantially throughout the coil strip steel material having a first hardness; subsequent to tempering the hardened strip steel material, grinding a first angle along an edge of the material to form a cutting edge portion and a remaining portion; and subsequent to said grinding, re-hardening the strip steel material locally at said cutting edge portion by reheating and quenching the strip steel material locally at said cutting edge portion such that the microstructure of the strip steel material substantially throughout said cutting edge portion is untempered martensite having a second hardness that is greater than the first hardness, while the tempered martensite microstructure having the first hardness remains the microstructure substantially throughout the remaining portion.