JPH05320818A - Wear resistant sleeve roll - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a sleeve roll by specifying the chemical compsn. of a wear resistant sleeve roll by a centrifugal casting. CONSTITUTION:The objective sleeve roll is manufactured by the centrifugal casting and its chemical compsn. is constituted of, by weight, 2.0 to 3.0% C, 0.2 to 1.5% Si, <=1.5% Mn, 10 to 20% Cr and 3 to 8% Nb, and the balance substantial Fe and Nb carbides are unevenly distributed on the outer face side of the roll. This low chromium material prepared is suitable for centrifugal casting and has a stronger wear resistance than that of a high chromium material and can withstand continuous use for long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasion resistant sleeve roll mainly used for a crusher roll.

[0002]

2. Description of the Related Art Conventionally, a crusher roll is a statically cast high Cr material (for example, C: 2.0 to 3.0 wt%, Cr: 25).
~ 30%) is used. This high Cr material is a material in which a large amount of high hardness M ₇ C ₃ type chromium carbide is generated in the structure and has good wear resistance.

[0003]

However, as described above, since the carbon content is high and the carbon content in the matrix structure is also high, the matrix structure is relatively brittle and chipping easily occurs. In addition, casting defects occur inside the statically cast roll,
There is a problem such as breakage during use. On the other hand, when centrifugal casting is performed, casting cracks frequently occur and stable production is difficult.

The present invention is a low-chromium material suitable for centrifugal casting, has a wear resistance higher than that of the conventional high-Cr material (for example, 27% Cr), and realizes continuous use of the roll for a long time. It is an object to provide a wear sleeve roll.

[0005]

As a means for achieving the above object, the present invention is a wear resistant sleeve roll formed by centrifugal force casting, the chemical composition of which is wt%, C: 2.0 to 3.0%, Si: : 0.2 to 1.5% Mn: 1.5% or less, Cr: 10 to 20% Nb: 3 to 8%, the balance being substantially Fe, and Nb carbide being unevenly distributed on the outer surface side of the roll.

[0006]

In the present invention, niobium carbide (NbC) is crystallized as a primary crystal by adding 3 to 8% of Nb. Since the specific gravity of this carbide is larger than that of the molten metal (the specific gravity of NbC is 7.8, it is unevenly distributed to the outer surface side by centrifugal casting. That is, a layer rich in niobium carbide is formed on the outer surface side,
This ensures wear resistance. On the other hand, on the inner surface side, a layer containing a small amount of niobium carbide is formed and workability is secured.

The hardness of the niobium carbide (NbC) is Hv 2400, and the hardness of M ₇ C ₃ type chromium carbide is
Harder than Hv 1800. Further, since niobium carbide has a more granular shape than chromium carbide, it is resistant to chipping wear.

[0008]

EXAMPLES First, the reasons for limiting the chemical composition of the high chromium cast iron material of the wear resistant sleeve roll of the present invention will be explained. In the following, all units of components are% by weight. C: 2.0 to 3.0% C combines with Cr to form various types of carbide having high hardness and improves wear resistance. If it is less than 2.0%, the amount of carbide will be too small and the abrasion resistance will be insufficient. If it exceeds 3.0%, the material becomes brittle.

Si: 0.2-1.5% Add 0.2% or more for deoxidation and improving the flowability of molten metal.
Addition of 1.5% or more deteriorates hardenability. In addition, the material becomes brittle. Mn: 1.5% or less Added for desulfurization of molten metal. Improves hardenability and wear resistance, but if 1.5% or more is added, the material becomes brittle.

Cr: 10 to 20% Cr partially forms a solid solution in the matrix to improve hardenability and combines with C to form a carbide, which improves wear resistance. Ten
If it is less than%, the effect is small. If it exceeds 20%, the amount of casting is increased and stable production becomes difficult. Nb: 3-8% Nb combines with C to form a high hardness MC type carbide.
Does not form double carbide with Cr or Fe. Also, it hardly forms a solid solution in the base. If it is less than 3%, Nb carbide does not crystallize as a primary crystal. Alternatively, even if crystallized, the segregation layer is not formed because the amount is extremely small (it cannot be determined). The segregation layer becomes thicker as the amount of Nb added increases, but if it is added at 8% or more, dissolution is very difficult, and further addition is unnecessary.

In addition to the above components, the cast iron material of the present invention comprises the balance Fe and inevitably mixed impurities (substantially Fe).
Is formed by. Both P and S are desirable because they make the material brittle, so it is preferable to keep P: less than 0.1% and S: less than 0.1%. Next, specific examples of manufacturing the sleeve roll according to the present invention will be described. For comparison, as a conventional example, a sleeve roll using a conventional high chromium cast iron material was also manufactured.

(Specific Manufacturing Example) As the molten metal, the one having the chemical composition shown in Table 1 was used.

[0013]

[Table 1]

The centrifugal casting conditions are as follows. -Chiller size: Diameter 600 x length 1300-G No: 140-Pouring temperature: 1406 ° C-Casting thickness: 100 mm test result-A layer with a large amount of niobium carbide was formed from the outer surface to a depth of 40 mm.

After the heat treatment (1000 ° C.), the hardness was measured, and it was found that the outer surface side (the portion containing a large amount of niobium carbide) ... H _RC 62 and the inner surface side (the portion containing a small amount of niobium carbide) ... H _RC 58.・ Nb is obtained by analyzing the composition of the inner surface of niobium carbide
It was 1.87%.

Comparative Example A molten metal having a chemical composition shown in Table 2 was used.

[0017]

[Table 2]

The casting conditions are the same as those of the concrete production examples. Test results: Chiller size: Diameter 1250 x Length 1000 ・ G No: 120 ・ Pouring temperature: 1398 ° C ・ Casting thickness: 110 mm Casting under the above conditions, When the mold was separated after 7 days, cracks had occurred.

[0019]

The present invention is an abrasion resistant sleeve roll formed by centrifugal force casting, the chemical composition of which is wt%, C: 2.0 to 3.0%, Si: 0.2 to 1.5% Mn: 1.5% or less, Cr: 10 to 20% Nb: 3 to 8%, the balance consisting essentially of Fe, and the Nb carbide being unevenly distributed on the outer surface of the roll. We were able to provide an excellent wear-resistant sleeve roll that can secure wear resistance that is superior to that of chrome materials and that can withstand continuous long-term use without causing chipping.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Cho Morikawa 64 Nishimukojima-cho, Amagasaki City, Hyogo Prefecture Kubota Amagasaki Plant Co., Ltd. (72) Inventor Kei Shikata 64 Kubota Amagasaki Plant, Amagasaki City Hyogo Prefecture Within

Claims (1)

[Claims] 1. An abrasion resistant sleeve roll formed by centrifugal force casting, the chemical composition of which is wt%, C: 2.0 to 3.0%, Si: 0.2 to 1.5% Mn: 1.5% or less, Cr: 10 to 20. % Nb: 3 to 8%, the balance being substantially Fe, and Nb carbide being unevenly distributed on the outer surface side of the roll, a wear-resistant sleeve roll.