Comparison of Knife Fabricated from Tool Steel by Heat Treatment and Knife Fabricated from Structural Steel by Hard Surface Welding

Abstract

Shears with the parallel knives are used for cutting bars to desired lengths from the mill stock. The knives are manufactured mostly from tool steel by heat treatment, while hard surface welding mainly used in repairs damaged parts. This paper presents a comparison of the ordinary knife fabrication from the tool steel X210CrW12 by heat treatment and knife fabrication from the structural steel St 52-3 by hard surface welding. Detail procedure of knife fabrication from tool steel is presented. The material X210CrW12 is received from supplier in soft annealed condition. After machining, following stress-relief annealing, preheating and austenizing, quenching, tempering and cooling on the end. The procedure of knife fabrication from the structural steel is simpler. The material St 52-3 is supplied in normalized condition. After machining and preheating, first welding is welding of ductile and high strength build-up layer, then following hard surface welding. An advantage of the fabrication by hard surface welding compared to the ordinary knives fabrication from tool steel is lower price, time of fabrication and possibility to extend total durability by several times repeating hard surface welding, but this requires skilled maintenance workers.