KR20240061444A - Method For Manufacturing Highly Wear-Resistant Milling Roll Through Characteristic Analysys Of Powder - Google Patents

Abstract

The present invention relates to a method for manufacturing a highly wear-resistant rolling roll by high-temperature molding of wear-resistant powder containing vanadium-based carbide. The present invention includes the steps of (a) preparing a powder containing vanadium-based carbide, (b) classifying the powder prepared in step (a) and analyzing the carbide size and particle size distribution and powder physical properties of the classified powder, (c) ) Selecting raw material powder for manufacturing wear-resistant rolling rolls according to the analysis results of step (b), (d) high-temperature molding of the raw material powder in step (c) to manufacture bulk products of wear-resistant rolling rolls It is characterized by comprising the step of:

Description

{Method For Manufacturing Highly Wear-Resistant Milling Roll Through Characteristic Analysys Of Powder}

The present invention relates to a method of manufacturing a high wear-resistant rolling roll by high-temperature molding of wear-resistant powder containing vanadium-based carbide.

Recently, as the strength of steel materials has increased, rolling rolls used as tool steel in the rolling process of manufacturing raw steel materials into shapes such as plates or bars are also required to have higher wear resistance properties.

Since the rolling roll of the rolling process forms the final product by contacting the material being processed, the wear of the rolling roll increases as the strength of the steel material being processed increases.

As one of the high-wear-resistant rolling roll manufacturing methods, wear-resistant powder containing vanadium-based carbide is mainly used, and a representative example is the CPM-9V product manufactured using a gas atomizer method. The wear-resistant powder used here is ultimately manufactured as a bulk product through a hot isostatic pressing (HIP) process. For example, in Korean Patent Publication No. 10-2008-0043251, the HIP process is applied to high temperature molding of powder particles formed by powder metallurgy.

However, since the wear resistance characteristics of the bulk product finally manufactured through the HIP process for high temperature molding change depending on the powder particle size, a rolling roll manufacturing method that can secure optimal physical properties suitable for high wear resistance rolling rolls is needed in response to this. This is being demanded.

Korean Patent Publication No. 10-2008-0043251 (published May 16, 2008)

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The purpose of the present invention is to create a high-wear-resistant rolling roll through powder characteristic analysis that can secure optimal physical properties suitable for high-wear-resistant rolling rolls by high-temperature molding with raw material powder selected according to the analysis results of wear-resistant powder containing vanadium-based carbide. The purpose is to provide a manufacturing method.

A method for manufacturing a high wear resistance rolling roll through powder characteristic analysis according to the present invention to achieve the above object includes the steps of (a) preparing powder containing vanadium-based carbide; (b) classifying the powder prepared in step (a) and analyzing the carbide size, particle size distribution, and powder physical properties of the classified powder; (c) selecting raw material powder for manufacturing wear-resistant rolling rolls according to the analysis results of step (b); (d) manufacturing a bulk product of wear-resistant rolling rolls by high-temperature molding of the raw material powder of step (c).

In addition, in step (a), CPM-9V product was used as a powder containing vanadium-based carbide, and its composition was C 1.85 wt%, Mn 0.44 wt%, Si 0.98 wt%, Cr 5.18 wt%, Mo 1.33 wt%, V 8.8wt%, the remainder is Fe.

In addition, in step (c), a powder is selected that has a high Vickers hardness and a small amount of wear due to a large carbide fraction and area inside the powder.

In addition, in step (d), a hot isostatic pressure process (HIP) is used for high temperature molding, and the hot isostatic pressure process is characterized by heat treatment at an ambient temperature of 1100 to 1700°C, a pressure of 900 to 1100 bar, and a process time of 3 to 5 hours. do.

According to the present invention, powder containing vanadium-based carbide is classified, the fraction and area of carbide are analyzed for the classified powder, and the raw material powder for the wear-resistant rolling roll is selected according to the analysis results, so that the carbide size and fraction are large. By high-temperature molding of raw material powder, a high-wear rolling roll with high hardness and low wear can be manufactured.

Figure 1 is an SEM photograph showing the particle distribution of connected carbide in powder with a powder size of 500㎛ or more;
Figure 2 is an SEM photograph showing the size and distribution of carbides inside the powder by powder particle size;
Figure 3 is a graph showing the carbide area ratio inside the powder by powder particle size;
Figure 4 is a flow chart of a method for manufacturing a high wear resistance rolling roll through powder property analysis according to an embodiment of the present invention;
Figure 5 is a graph showing particle size distribution for four groups of classified powders;
Figure 6 is an SEM photograph showing the dispersion state of carbides after performing the HIP process on four groups of classified powders;
Figure 7 is a graph showing the fraction and area of carbide for four groups of classified powders;
Figure 8 is a graph showing Vickers hardness for four groups of classified powders;
Figure 9 is a graph showing the amount of wear for four groups of classified powders;
Figure 10 is an SEM photograph showing the surfaces of four groups of classified powders.

Hereinafter, the present invention will be described by explaining embodiments of the present invention with reference to the attached drawings. The same reference numerals in each drawing indicate the same member. Additionally, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Additionally, when a part is said to “include” a certain component, this means that it may further include other components, rather than excluding other components, unless specifically stated to the contrary.

In general, the particle size of the powder material used to manufacture rolling rolls shows a normal distribution, and powders with a powder size of 500 ㎛ or more are inexpensive and are economically advantageous. Referring to FIG. 1, the distribution of connected carbide particles in powder over 500㎛ becomes a factor that may reduce hardness and wear resistance characteristics during high-temperature molding through hot isostatic pressure process (HIP).

The gas atomizer process completely dissolves the material alloy to be manufactured to form molten metal, and then sprays high-pressure gas onto the molten metal falling through a nozzle to produce the final powder. Here, when changing from molten metal to powder, the cooling rate may vary depending on the powder particle size, and because of this, differences may occur in the size and distribution of internal carbides at powder particle sizes of 50㎛, 100㎛, 200㎛, and 300㎛, as shown in Figure 2. there is. At this time, the average carbide size for each powder particle size was 0.064±0.053㎛, 0.054±0.060㎛, 0.137±0.099㎛, and 0.204±0.161㎛. In addition, when analyzing the area occupied by the carbide inside the powder (Area percentage), it is 17.437 ± 0.8815%, 11.68 ± 1.776%, 11.56 ± 15%, corresponding to the powder particle size (50㎛, 100㎛, 200㎛, 300㎛), as shown in Figure 3. It was found to be 2.074% and 14.17±2.485%.

Referring to FIG. 4, the high wear resistance rolling roll manufacturing method through powder property analysis according to an embodiment of the present invention prepares powder containing vanadium-based carbide (S100), classifies the prepared powder, and determines the carbide size of the classified powder. and particle size distribution and powder physical properties are analyzed (S200), and according to the analysis results, raw material powder for manufacturing wear-resistant rolling rolls is selected (S300), and the selected raw material powder is subjected to high-temperature molding to produce bulk products of wear-resistant rolling rolls. It consists of a manufacturing step (S400).

In the S100 step, CPM-9V product is used as a powder containing vanadium-based carbide, and its composition is C 1.85wt%, Mn 0.44wt%, Si 0.98wt%, Cr 5.18wt%, Mo 1.33wt% , V 8.8wt%, the remainder is Fe.

In step S200, the powder of the CPM-9V product is classified according to powder size to prepare four groups of powders. Referring to Figure 5, the first group powder is an initial powder and classified into a particle size of about 400㎛ or less (40mesh), the second group powder is classified into a particle size of about 300㎛ or less (50mesh), and the third group powder is classified into a particle size of about 200㎛ or less. Classification (70mesh), Group 4 powder is classified into powders (140mesh) with a particle size of about 100㎛ or less.

Bulk materials are manufactured as base materials for high wear-resistant rolling rolls through the hot isostatic pressure process (HIP) for four groups of powders. In the example, the hot isostatic process (HIP) is performed at 1165°C, 1000 bar, and 4 hours.

As a result of the hot isostatic pressure process (HIP), carbides were well separated and dispersed in the first to fourth group classified powders, as shown in the SEM photo of FIG. 6.

The fraction and area of carbide are analyzed for the classified powders of the first to fourth groups. As a result of the analysis, in the fourth group of classified powders (40mesh) with large powder particle size, the carbide fraction inside the powder was 24.38% and the area was 0.418㎛ ² , which was relatively higher than the classified powders of other groups (see Figure 7).

When analyzing the Vickers hardness of the classified powders of the first to fourth groups, the classified powder of the fourth group (40mesh) was found to be 594 HV, which is relatively higher than the classified powders of other groups (see Figure 8). .

When analyzing the weight loss of the classified powders of the first to fourth groups, the weight loss of the classified powders of the fourth group (40mesh) was found to be 6 mg, which is relatively less than the classified powders of the other groups (see Figure 9).

In this analysis, as in the 4th group classified powder (40mesh), the larger the carbide size and fraction, the higher the hardness and the lower the amount of wear. The fourth group's classified powder (40mesh) showed a small amount of wear and was analyzed to have relatively excellent wear resistance characteristics. From this, it can be seen that there is a conflicting relationship between the size of carbide and the amount of wear.

Figure 10 is an SEM photograph showing the surfaces of four groups of classified powders, and the surfaces of each group of classified powders appear in two aspects (Torn surface, Scratched surface).

Most (80-90%) of the surfaces of the first group of classified powders (140mesh) appeared as torn surfaces, and the surfaces of the second group of classified powders (70mesh) showed a reduced torn surface. It was found that some scratched areas were formed, and the Torn surface of the classified powder (50mesh) of the third group was further reduced, showing less scratched area than that of the fourth group. Most (80-90%) of the surface of the classified powder (40mesh) appeared as a scratched area.

As in the 4th group classified powder (40mesh), the larger the carbide size, the higher the probability of scratched area occurring, and as a result, the amount of wear was small, showing that the wear resistance characteristics were relatively excellent.

In step S300, raw material powder for manufacturing wear-resistant rolling rolls is selected according to the analysis results. In other words, when selecting raw material powders, select raw material powders with as large a powder particle size as possible, excluding defective factors in high-wear rolling roll products such as the generation of connected carbides inside the powder and uneven distribution of carbides.

In step S400, the selected raw material powder is molded at high temperature to manufacture a bulk product of wear-resistant rolling rolls. Here, hot isostatic pressure sintering method is applied for high temperature forming. Here, the hot isostatic pressure process (HIP) is a heat treatment performed at an ambient temperature of 1100 to 1700°C, a pressure of 900 to 1100 bar, and a process time of 3 to 5 hours. In the example, it is performed at 1165°C, 1000 bar, and 4 hours.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be.

Claims (4)

(a) preparing a powder containing vanadium-based carbide;
(b) classifying the powder prepared in step (a) and analyzing the carbide size, particle size distribution, and powder physical properties of the classified powder;
(c) selecting raw material powder for manufacturing wear-resistant rolling rolls according to the analysis results of step (b);
(d) manufacturing a bulk product of the wear-resistant rolling roll by high-temperature molding of the raw material powder of step (c). According to paragraph 1,
In step (a), CPM-9V product is used as a powder containing vanadium-based carbide, and its composition is as follows. A method of manufacturing a high wear resistance rolling roll through powder characteristic analysis.
C 1.85wt%,
Mn 0.44wt%,
Si 0.98wt%,
Cr 5.18wt%,
Mo 1.33wt%,
V 8.8wt%,
The rest Fe According to paragraph 1,
In step (c), a high abrasion resistance rolling roll manufacturing method through powder characteristic analysis is characterized in that a powder having a high Vickers hardness and low wear amount is selected because the carbide fraction and area inside the powder are large. According to paragraph 1,
In step (d), a hot isostatic pressure process (HIP) is used for high temperature molding,
The hot isostatic pressure process is a method of manufacturing a high wear resistance rolling roll through powder property analysis, characterized in that the heat treatment is performed at an ambient temperature of 1100 to 1700°C, a pressure of 900 to 1100 bar, and a process time of 3 to 5 hours.