Centrifugally cast hot-rolling composite roll

Patent metadata

Field	Value
Publication number	US-9358758-B2
Application number	US-201414758694-A
Country	US
Kind code	B2
Filing date	May 2, 2014
Priority date	May 2, 2013
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

A centrifugally cast hot-rolling composite roll comprising (a) an outer layer made of cast iron having a chemical composition comprising by mass 2.5-3.5% of C, 1.3-2.4% of Si, 0.2-1.5% of Mn, 3.5-5.0% of Ni, 0.8-1.5% of Cr, 2.5-5.0% of Mo, 1.8-4.0% of V, and 0.2-1.5% of Nb, the balance being Fe and inevitable impurities, a mass ratio of Nb/V being 0.1-0.7, and a mass ratio of Mo/V being 0.7-2.5, and meeting the condition of 2.5≦V+1.2Nb≦5.5, and having a structure comprising 0.3-10% by area of a graphite phase; (b) a shaft portion made of ductile cast iron in which the area ratio of ferrite is 35% or less; and (c) an intermediate cast iron layer.

First claim

What is claimed is:

1. A centrifugally cast hot-rolling composite roll comprising (a) an outer layer made of cast iron having a chemical composition comprising by mass 2.5-3.5% of C, 1.3-2.4% of Si, 0.2-1.5% of Mn, 3.5-5.0% of Ni, 0.8-1.5% of Cr, 2.5-5.0% of Mo, 1.8-4.0% of V, and 0.2-1.5% of Nb, the balance being Fe and inevitable impurities, a mass ratio of Nb/V being 0.1-0.7, and a mass ratio of Mo/V being 0.7-2.5, and meeting the condition of 2.5≦V+1.2 Nb≦5.5, and having a structure comprising 0.3-10% by area of a graphite phase; (b) a shaft portion made of ductile cast iron; and (c) an intermediate cast iron layer.

2. The centrifugally cast hot-rolling composite roll according to claim 1 , wherein the total amount of V and Nb in said intermediate layer near the boundary with the shaft portion is 70% or less of that at said discard diameter of the outer layer; and wherein the Cr content in said intermediate layer near the boundary with the shaft portion is 80% or more of that at said discard diameter of the outer layer.

3. The centrifugally cast hot-rolling composite roll according to claim 2 , wherein said outer layer further comprises 0.1-5.0% of W.

4. The centrifugally cast hot-rolling composite roll according to claim 3 , wherein the chemical composition of said outer layer meets the conditions of the following formulae (1)-(3):
Si≦3.2/[0.283(C−0.2V−0.13Nb)+0.62]  (1),

(C−0.2V−0.13Nb)+(Cr+Mo+0.5W)≦9.5  (2), and

1.5≦Mo+0.5W≦5.5  (3).

5. The centrifugally cast hot-rolling composite roll according to claim 1 , wherein said outer layer further comprises 0.1-5.0% of W.

6. The centrifugally cast hot-rolling composite roll according to claim 5 , wherein the chemical composition of said outer layer meets the conditions of the following formulae (1)-(3):
Si≦3.2/[0.283(C−0.2V−0.13Nb)+0.62]  (1),

(C−0.2V−0.13Nb)+(Cr+Mo+0.5W)≦9.5  (2), and

1.5≦Mo+0.5W≦5.5  (3).

7. The centrifugally cast hot-rolling composite roll according to claim 1 , wherein said outer layer further comprises at least one selected from the group consisting of 0.003-5.0% of Ti, 0.01-2.0% of Al, 0.01-0.5% of Zr, 0.001-0.5% of B, and 0.1-10.0% of Co by mass.

8. The centrifugally cast hot-rolling composite roll according to claim 1 , wherein the matrix of said outer layer has Vickers hardness of 560 or more.

9. The centrifugally cast hot-rolling composite roll according to claim 1 , wherein the circumferential residual compression stress of said outer layer surface at a longitudinal roll center is 150-500 MPa at a discard diameter.

10. The centrifugally cast hot-rolling composite roll according to claim 1 , wherein the said outer layer has fracture toughness K IC of 18.5 MPa·m 1/2 or more.

11. The centrifugally cast hot-rolling composite roll according to claim 1 , wherein the matrix of said outer layer contains 3.2% or less by mass of Si.

Assignees

• Hitachi Metals Ltd

Inventors

• Oda Nozomu
• Segawa Takayuki
• Nozaki Yasunori

Classifications

• B21B27/021

  Rolls for sheets or strips · CPC title

• C22C38/54

  with boron · CPC title

• C22C37/08

  with nickel · CPC title

• B21B27/00

  Rolls, {roll alloys or roll fabrication}(shape of working surfaces required by special processes B21B1/00); Lubricating, cooling or heating rolls while in use · CPC title

• C22C38/02

  containing silicon · CPC title