TOOL FOR PIERCING MILL

摘要

A tool for a piercing mill with excellent wear resistance and a method for producing the tool for a piercing mill are provided.;A scale layer is formed in a surface layer of a substrate steel having a composition containing, on a mass % basis, C: 0.05% to 0.5%, Si: 0.1% to 1.5%, Mn: 0.1% to 1.5%, Cr: 0.1% to 1.5%, Mo: 0.6% to 3.5%, W: 0.5% to 3.5%, and Nb: 0.1% to 1.0% and further containing Co: 0.5% to 3.5% and Ni: 0.5% to 4.0% so as to satisfy 1.0

主权项

1. A tool for a piercing mill, the tool comprising a scale layer in a surface layer of a substrate steel, wherein the substrate steel has a composition containing, on a mass % basis:
C: 0.05% to 0.5%, Si: 0.1% to 1.5%, Mn: 0.1% to 1.5%, Cr: 0.1% to 1.5%, Mo: 0.6% to 3.5%, W: 0.5% to 3.5%, and Nb: 0.1% to 1.0%, and further containing Co: 0.5% to 3.5% and Ni: 0.5% to 4.0% so as to satisfy formula (1) below, with the balance being Fe and incidental impurities; wherein the scale layer includes a net structure scale layer that is formed on a substrate steel side, has a thickness of 10 to 200 μm in a depth direction, and is complicatedly intertwined with a metal; and wherein a microstructure on the substrate steel side in a range of at least 300 μm in the depth direction from an interface between the net structure scale layer and the substrate steel contains a ferrite phase at an area fraction of 50% or more, the ferrite phase containing 400/mm2 or more of ferrite grains having a maximum length of 1 to 60 μm,
1.0