Cemented carbide and its production method, and rolling roll

Patent metadata

Field	Value
Publication number	US-10920304-B2
Application number	US-201716322231-A
Country	US
Kind code	B2
Filing date	Aug 1, 2017
Priority date	Aug 1, 2016
Publication date	Feb 16, 2021
Grant date	Feb 16, 2021

Abstract

A cemented carbide comprising 55-90 parts by mass of WC particles, and 10-45 parts by mass of an Fe-based binder phase, the binder phase having a composition comprising 2.5-10% by mass of Ni, 0.2-1.2% by mass of C, 0.5-5% by mass of Cr, 0.2-2.0% by mass of Si, 0.1-3% by mass of W, 0-5% by mass of Co, and 0-1% by mass of Mn, the balance being substantially Fe and inevitable impurities, and the cemented carbide being substantially free from composite carbides having major axes of 5 μm or more. This cemented carbide is produced by cooling at a cooling rate of 60° C./hour or more between 900° C. and 600° C., after vacuum sintering.

First claim

What is claimed is:

1. A cemented carbide comprising 55-90 parts by mass of WC particles, and 10-45 parts by mass of a binder phase containing Fe as a main component,
said binder phase having a composition comprising
2.5-10% by mass of Ni,
0.2-1.2% by mass of C,
0.5-5% by mass of Cr,
0.2-2.0% by mass of Si,
0.1-3% by mass of W,
0-5% by mass of Co, and
0-1% by mass of Mn,
the balance being substantially Fe and inevitable impurities; and
said cemented carbide being substantially free from composite carbides having major axes of 5 μm or more.

2. The cemented carbide according to claim 1 , wherein said WC particles have a median diameter D50 of 2-10 μm.

3. The cemented carbide according to claim 1 , said inevitable impurities in said binder phase are at least one selected from the group consisting of Mo, V, Nb, Ti, Al, Cu, N and O.

4. The cemented carbide according to claim 1 , wherein at least one selected from the group consisting of Mo, V and Nb in said inevitable impurities is 2% or less by mass in total.

5. The cemented carbide according to claim 4 , wherein at least one selected from the group consisting of Ti, Al, Cu, N and O in said inevitable impurities is 0.5% or less by mass each and 1% or less by mass in total.

6. The cemented carbide according to claim 4 , wherein a bainite phase and/or a martensite phase in said binder phase is 50% or more by area in total.

7. The cemented carbide according to claim 1 , wherein said cemented carbide has compressive yield strength of 1200 MPa or more.

8. A rolling composite roll comprising an outer layer made of the cemented carbide recited in claim 1 , said outer layer being metallurgically bonded to a peripheral surface of a steel sleeve or shaft.

9. A method for producing the cemented carbide recited in claim 1 , comprising
press-molding a mixture comprising 55-90 parts by mass of WC powder, and 10-45 parts by mass of metal powder comprising 2.5-10% by mass of Ni, 0.3-1.7% by mass of C, 0.5-5% by mass of Cr, 0.2-2.0% by mass of Si, 0-5% by mass of Co, and 0-2% by mass of Mn, the balance being Fe and inevitable impurities;
vacuum-sintering the resultant green body at a temperature from its liquid phase generation start temperature to said liquid phase generation start temperature+100° C.; and then
cooling the resultant sintered body at a cooling rate of 60° C./hour or more between 900° C. and 600° C.

Assignees

• Hitachi Metals Ltd

Inventors

• Ohata Takumi
• Matsumoto Shunji

Classifications

• C22C1/05

  Mixtures of metal powder with non-metallic powder (C22C1/08 takes precedence) · CPC title

• C22C1/051

  Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title

• B21B27/03

  Sleeved rolls {(B21B27/028 takes precedence)} · CPC title

• C22C29/005

  comprising a particular metallic binder · CPC title