Roll surface layer material for hot rolling with excellent fatigue resistance produced by centrifugal casting, and composite roll for hot rolling produced through centrifugal casting

Patent metadata

Field	Value
Publication number	US-9975158-B2
Application number	US-201214352441-A
Country	US
Kind code	B2
Filing date	Oct 15, 2012
Priority date	Oct 19, 2011
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

There is provided a roll surface layer material including a roll surface layer with excellent fatigue resistance. The roll surface layer material has a composition including, on a mass % basis, C: 2.3% to 2.9%, Si: 0.2% to 0.8%, Mn: 0.2% to 1.0%, Cr: 5.0% to 7.5%, Mo: 4.4% to 6.5%, V: 5.3% to 7.0%, Nb: 0.6% to 1.5%, and Co: 0.1% to 4.0% so as to satisfy 14.0≤(Mo+1.7V)≤17.0 (where Mo represents a content (mass %) of Mo and V represents a content (mass %) of V) and further including Al: 0.001% to 0.03% and/or REM: 0.001% to 0.03%, wherein a carbide is contained at an area fraction of 13% to 40%. A composite roll obtained by integrally welding a shaft member to the roll surface layer member is treated as a centrifugal cast roll that includes a surface layer with excellent fatigue resistance.

First claim

The invention claimed is:

1. A roll surface layer material produced by centrifugal casting for a hot rolling mill, the roll surface layer material having excellent fatigue resistance and a compression 0.2% proof strength of 2000 MPa or more, and being used for a centrifugal cast roll for a hot rolling mill composite roll having a hardness of 79 to 88 HS, a composition of the roll surface layer material consisting of, on a mass % basis:
Carbon (C): 2.3% to 2.9%;
Silicon (Si): 0.2% to 0.8%;
Manganese (Mn): 0.2% to 1.0%;
Chromium (Cr): 5.0% to 7.5%;
Molybdenum (Mo): 4.4% to 6.5%;
Vanadium (V): 5.3% to 7.0%;
Niobium (Nb): 0.6% to 1.5%;
Cobalt (Co): 0.1% to 4.0%, and
at least one of aluminum (Al) or rare earth metals (REM) in an amount of 0.001% to 0.03%,
so as to satisfy formula (1) below, with the balance being iron (Fe) and incidental impurities including phosphor (P): 0.05% or less, sulfur (S): 0.05% or less and nitrogen (N): 0.06% or less,
and wherein an area fraction of carbides in the roll surface layer material is in the range of 13% to 20%,
14.0≤(Mo+1.7V)≤17.0  (1)

wherein Mo represents a content (mass%) of molybdenum and V represents a content (mass%) of vanadium.

2. A centrifugal cast roll for a hot rolling mill composite roll having a hardness of 79 to 88 HS, the centrifugal cast roil having excellent fatigue resistance and a compression 0.2% proof strength of 2000 MPa or more, and including a surface layer and an internal layer integrally welded to the surface layer, a composition of the roll surface layer material consisting of, on a mass % basis:
Carbon (C): 2.3% to 2.9%;
Silicon (Si): 0.2% to 0.8%;
Manganese (Mn): 0.2% to 1.0%;
Chromium (Cr): 5.0% to 7.5%;
Molybdenum (Mo): 4.4% to 6.5%;
Vanadium (V): 5.3% to 7.0%;
Niobium (Nb): 0.6% to 1.5%;
Cobalt (Co): 0.1% to 4.0%, and
at least one of aluminum (Al) or rare earth metals (REM) in an amount of 0.001% to 0.03%,
so as to satisfy formula (1) below, with the balance being iron (Fe) and incidental impurities including phosphor (P): 0.05% or less, sulfur (S): 0.05% or less and nitrogen (N): 0.06% or less,
and wherein an area fraction of carbides in the roll surface layer material is in the range of 13% to 20%,
14.0≤(Mo+1.7V)≤17.0  (1)

wherein Mo represents a content (mass%) of molybdenum and V represents a content (mass%) of vanadium.

Assignees

• Jfe Steel Corp

Inventors

• Ichino Kenji
• Mochida Tetsuo
• Shibata Hiromitsu

Classifications

• C22C37/06

  containing chromium · CPC title

• C22C37/10

  containing aluminium or silicon · CPC title

• C21D1/25

  Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten") · CPC title

• B22D13/02 Primary

  of elongated solid or hollow bodies, e.g. pipes, in moulds rotating around their longitudinal axis · CPC title

• B21B27/02

  Shape or construction of rolls (for rolling metal of indefinite length in repetitive shapes specially designed for the manufacture of particular objects B21H8/02 {; B21B27/005 takes precedence}) · CPC title