KR-20260066373-A - Ni-Cr BASED ALLOY FOR RADIANT TUBE HAVING HIGHLY IMPROVED HIGH TEMPERATURE CREEP RESISTANCE AND METHOD OF MANUFACTURING THE SAME

Abstract

The present invention relates to a Ni-Cr alloy for radiation tubes having excellent high-temperature creep characteristics and a method for manufacturing the same.

Inventors

• 박재현

Assignees

• 재단법인 포항산업과학연구원

Dates

Publication Date

20260512

Application Date

20241104

Claims (4)

1. In wt%, Carbon (C): 0.17–0.3%, Chromium (Cr): 30–35%, Nickel (Ni): 45–55%, Manganese (Mn): ≤1%, Silicon (Si): ≤1%, Sum of one or both of Niobium (Nb) and Vanadium (V): 1–3%, Tungsten (W): 5–18%, Tantalum (Ta): 0.1–1.5%, Hafnium (Hf): 0.1–1.5%, Sum of one or both of Rhenium (Re) and Ruthenium (Ru): 0.1–3%, Boron (B): 0.001–0.02%, Yttrium (Y): 0.01–1.0%, Sum of Lanthanum (La) and Cerium (Ce): 0.1–1.0%, Balance of Fe and other unavoidable impurities A Ni-Cr alloy for radiation tubes with excellent high-temperature creep properties, including and satisfying Y/(La+Ce) = 0.8~1.2.
2. In claim 1, The above Ni-Cr alloy is a Ni-Cr alloy for radiation tubes having an austenite single-phase structure and excellent high-temperature creep properties.
3. A step of preparing a molten metal comprising, in weight%, carbon (C): 0.17~0.3%, chromium (Cr): 30~35%, nickel (Ni): 45~55%, manganese (Mn): 1% or less, silicon (Si): 1% or less, sum of one or two of niobium (Nb) and vanadium (V): 1~3%, tungsten (W): 5~18%, tantalum (Ta): 0.1~1.5%, hafnium (Hf): 0.1~1.5%, sum of one or two of rhenium (Re) and ruthenium (Ru): 0.1~3%, boron (B): 0.001-0.02%, and the remainder being Fe and other unavoidable impurities; Step of discharging the above molten metal into a ladle; and The method includes the step of casting the above-mentioned molten metal to obtain a Cr-Ni alloy, and A method for manufacturing a Ni-Cr alloy for radiation tubes with excellent high-temperature creep properties, wherein when tapping the above molten metal, yttrium (Y) 0.01~1.0%, the sum of lanthanum (La) and cerium (Ce) 0.1~1.0%, and Y/(La+Ce) = 0.8~1.2 are added to the molten metal being tapped, and the yttrium (Y) has a massive form with an average diameter of 5~10mm, the lanthanum (La) has a massive form with an average diameter of 8~13mm, and the cerium (Ce) has a massive form with an average diameter of 10~15mm.
4. In Paragraph 3, A method for manufacturing a Ni-Cr alloy for radiation tubes with excellent high-temperature creep characteristics, wherein the above-mentioned molten metal is cast by a centrifugal casting method using a mold.

Description

Ni-Cr-based alloy for radiant tube having highly improved high-temperature creep resistance and method of manufacturing the same The present invention relates to a Ni-Cr alloy for radiation tubes with excellent high-temperature creep characteristics and a method for manufacturing the same. Generally, radiant tubes are installed inside the annealing furnaces used in steel mills to heat cold-rolled steel sheets for plating or subsequent processes. The steel sheets are heated indirectly by radiant heat passing through the outer layer of the tubes after the interior of the tubes has been heated by a flame. These radiant tubes are constructed by centrifugally casting heat-resistant materials or welding a straight section of sheet metal into a tubular shape to a curved section produced by sand casting. When such radiation tubes are applied, for example, in the manufacture of electrical steel sheets, the operating temperature is 1000°C or higher, so the creep deformation resistance and fracture resistance characteristics at high temperatures are very important factors in determining the product's lifespan. Previously, nickel-based heat-resistant alloys such as Super22H containing 25~35% Cr and 40~50% Ni were mainly used for these radiation tubes. However, even with these heat-resistant alloys, there are problems such as increased replacement costs and reduced productivity due to shortened lifespan caused by the deterioration of creep characteristics (a phenomenon in which deformation occurs even below the yield strength and eventually leads to fracture when exposed to given stress and high temperature for a long time), such as cracking or sagging due to deformation when used for a long time. To address these issues, there have been attempts to improve high-temperature properties by adding rare earth elements. Patent Document 1 describes a technology that uses powder of 100 μm or less as a rare earth additive material. However, due to the disadvantage that rare earth elements cause a rapid oxidation reaction when in contact with high-temperature molten metal, alloying is difficult and the effect is not achieved, which has significant limitations in use. To improve this, Patent Document 2 proposes a Cr-Ni alloy for radiation tubes with excellent high-temperature deformation resistance and crack resistance, comprising, in weight percent, carbon (C): 0.17~0.3%, chromium (Cr): 30~35%, nickel (Ni): 45~55%, manganese (Mn): 1% or less, silicon (Si): 1% or less, sum of one or two of niobium (Nb) and vanadium (V): 1~3%, tungsten (W): 5~18%, tantalum (Ta): 0.1~1.5%, hafnium (Hf): 0.1~1.5%, boron (B): 0.001-0.02%, yttrium (Y): 0.05~1.5%, and the remainder being Fe and other unavoidable impurities, with an average spacing between dendrites of 30㎛ or less. A method for manufacturing the same is proposed. However, along with continuous demands for improving the lifespan of steel mill equipment and extending the replacement cycle of equipment parts, there is a growing need for radiation tubes with an extended lifespan for high-temperature operating conditions of over 1000°C. Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field. In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form. In this description, expressions such as “include” or “equipped” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described. Unless otherwise specifically defined in the specification of the present invention, % units mean weight %. The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this spec