Roll for hot rolling having enhanced abrasion resistance and reduced carbide segregation

• US 6,095,957 A
• Filed: 01/29/1998
• Issued: 08/01/2000
• Est. Priority Date: 06/18/1996
• Status: Expired due to Term

• Current Assignee: Kawasaki Steel Corporation (JFE Holdings Incorporated)
• Original Assignee: Kawasaki Steel Corporation (JFE Holdings Incorporated)
• Inventors: Yuda, Kohji, Ichino, Kenji, Koseki, Tomoya, Toyooka, Takaaki
• Primary Examiner(s): Cuda, Irene
• Application Number:
  US09/011,152
• Time in Patent Office: 915 Days
• Field of Search: 492/54, 492/58
• US Class Current: 492/54
• CPC Class Codes: B21B 27/00 Rolls, roll alloys or roll fabricationshape of working surfaces required by special processes B21B1/00; Lubricating, cooling or heating rolls while in use
• CPC Class Codes: B32B 15/011 all layers being formed of iron alloys or steels

Abstract

High-quality high-speed steel roll which is markedly excellent in abrasion resistance and free of carbide segregation even in the case of production by centrifugal casting of economical benefit; it comprises an outer layer containing, by all weight ratios, C; 2.4-2.9%, Si; not more than 1%, Mn; not more than 1%, Cr; 12-18%, Mo; 3-9%, V; 3-8% and Nb; 0.5-4%, and meeting with the following equations (1) and (2) at one time,

0.27≧Mo (%)/Cr (%)≦0.7                       (1)

C (%)+0.2·Cr (%)≦6.2                       (2)

the outer layer further containing as the balance Fe and unavoidable impurities.

Claims

1. A hot-rolling roll characterized in that the roll comprises an outer layer containing, by weight, C;

2.4-2.9%, Mo;

3-9%, V;

3-8% and Nb;

0.5-4%, and with Mo, Cr and C being controlled within the limitations of both of the following equations (1) and (2) at one time,

space="preserve" listing-type="equation">0.27≦

Mo (%)/Cr (%)≦

0.7 (1)

space="preserve" listing-type="equation">C (%)+0.2·

Cr (&

)≦

6.2 (2)

the outer layer further containing as the balance fe and unavoidable impurities.

3. A hot-rolling roll according to claims 1 and 2, characterized in that the outer layer further includes a MC type carbide and a M₇ C₃ type carbide in their total area of 13-30%.

4. A hot-rolling roll according to claim 3, characterized in that the M₇ C₃ type carbide is present in an area of not less than 6%.

5. A hot-rolling roll according to claims 1 and 2, characterized in that the roll further includes an inner layer formed of a spherical graphite cast iron or a graphite steel and held in integrally fusion-bonded relation to the outer layer, the inner layer containing, by all weight ratios, C;

2.5-4.0%, Si;

1.5-3.5%, Mn;

not more than 1.5%, Cr;

not more than 3%, Mo;

not more than 3%, V;

not more than 3% and Nb;

not more than 2%, and further containing as the balance Fe and unavoidable impurities.

6. A hot-rolling roll according to claims 1 and 2, characterized in that the roll further includes an intermediate layer interposed between the outer layer and the inner layer and held in integrally fusion-bonded relation to the outer and inner layers, the intermediate layer containing, by all weight ratios, C;

0.8-3.0%, Si;

0.3-3.0%, Mn;

not more than 1.5%, Cr;

not more than 10%, Mo;

not more than 4%, V;

not more than 5% and Nb;

not more than 3%, and further containing as the balance Fe and unavoidable impurities.

7. A hot-rolling roll according to claim 6, characterized in that the ratio of the intermediate layer admixed into the inner layer material is in the range of 5-20%.

8. A hot-rolling roll according to claim 6, characterized in that the ratio of the intermediate layer admixed into the outer layer material is in the range of 5-50%.

9. A hot-rolling roll according to claim 5 or 6, characterized in that either one or both layers of the inner and intermediate layer s further include either one or both components of Ni;

not more than 5% and Co;

not more than 6%.

10. A hot-rolling roll of according to claim 1 or 2, characterized in that the outer layer is derivable from centrifugal casting.

2. A hot-rolling roll characterized in that the roll comprises an outer layer containing, by all weight ratios, C;

2.4-2.9%, Si;

not more than 1%, Mn;

not more than 1%, Cr;

12-18%, Mo;

3-9%, V;

3-8% and Nb;

0.5-4%, and meeting with the following equations (1) and (2) at one time,

space="preserve" listing-type="equation">0.27≦

Mo (%)/Cr (%)≦

0.7 (1)

space="preserve" listing-type="equation">C (%)+0.2·

Cr (%)≦

6.2 (2)

the outer layer further including one or more of Ni;

not more than 1.5%, Co;

not more than 6% and B;

not more than 0.1%, the outer layer further containing as the balance Fe and unavoidable impurities.