Laminated tool steel material and process for producing such tool steel material

摘要

A tool steel material is capable of having its carbides sufficiently fined in microstructure and also capable of reducing segregation of any of its constituent elements to the smallest possible amount in the material. In producing the material, a plurality of cast steel pieces are prepared and stacked to form a lamination pack. This lamination pack is then subjected to a hot-working process under pressure. As a result, the cast steel pieces of the pack are press-bonded to each other and unified. During this press-bonding process, the pack is also subjected to a diffusion heat treatment for enhancing diffusion of the elements of the material by permitting the elements to pass through a contact surface of each of the cast steel pieces, through which contact surface adjacent ones of the cast steel pieces are brought into contact with each other in the lamination pack.