JPS6173867A - Hot wear resistant member of dispersion strengthening sintered alloy steel - Google Patents

Abstract

PURPOSE:To obtain a hot wear resistant member having superior resistance to wear, surface roughening and breaking by uniformly dispersing vanadium carbide and a metallic carbide or nitride in a high-alloy steel as a matrix. CONSTITUTION:This hot wear resistant member has a structure formed by uniformly dispersing fine vanadium carbide and one or more kinds of components selected among the carbides and nitrides of the group IVa and Va metals in the periodic table and solid solns. each consisting of two or more kinds of such compounds in a high-alloy steel having a composition consisting of, by weight, 0.5-5% C, 3-10% Cr, 1-10% W and/or 2-15% Mo, 1-5% V, 5-20% Ni, 5-20% Co and the balance Fe with inevitable impurities as a matrix. The structure is composed of 2-20% vanadium carbide, 2-20% metallic carbide or nitride and the balance high-alloy steel.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a hot wear-resistant member made of dispersion-strengthened sintered alloy steel having excellent wear resistance, roughness resistance, and cracking resistance. It is something.

[Conventional technology]

Generally, hot wear-resistant members such as hot rolling rolls and hot rolling guide rollers have a carbon content of 0.65 to 1.2%.

Cr: 3.5-4.5%.

W: 1.5-22%.

MO: 2-9%.

V: O, a~5%.

Contains, and if necessary, (:, o: 0.5-20%.

A molten carbide dispersion-strengthened alloy steel having a composition (the above weight %, below % indicates weight %) containing Fe and the remainder consisting of Fe and unavoidable impurities is cast into an ingot, and this ingot is forged and rolled. It is manufactured through a process of finishing it into a predetermined shape and size.

[Problem that the invention seeks to solve]

However, this conventional carbide dispersion-strengthened alloy steel hot wear-resistant member does not have sufficient wear resistance, and attempts have been made to increase the content of carbide-forming components in order to improve wear resistance. 1=, but in this case, segregation and coarsening of carbides occurred, and particularly the decrease in cracking resistance was remarkable. In addition, in order to solve the problem of segregation and coarsening of carbides, attempts have been made to manufacture the hot wear-resistant member using a powder metallurgy method, but in this case, sufficient roughness resistance was not shown. It was something that didn't exist.

[Means for solving problems]

Therefore, from the above-mentioned viewpoints, the present inventors conducted research from a material perspective in order to obtain a hot wear-resistant member with excellent wear resistance, roughness resistance, and cracking resistance. The above-mentioned hot wear-resistant member is made of a high-alloy steel base, fine vanadium carbide (hereinafter referred to as VC), and nitrides and carbonitrides of group 4a and 5a metals of the periodic table (hereinafter referred to as Ti and carbonitrides, respectively). N, Zr
N, Hf N, VN, Ta N.

Nb N, Ti CN, Zr CN, Hr CN, VC
N.

A structure in which one or more of Ta CN and Nb CN) and two or more of these solid solutions (hereinafter collectively referred to as metal carbon/nitride) are uniformly dispersed. and the content of VC and metal carbon/nitride is each 2 to 20%, and the remaining high alloy steel base is C: 0.5 to 5%.

Cr: 3-10%.

One or two of W: 1-10% and MO: 2-15%.

■ = 1-5%.

Ni: 5-20%.

CO: 5-20%.

Fe and unavoidable impurities: remainder.

When constructed of dispersion-strengthened sintered alloy steel having a composition of
The nitride ensures excellent wear resistance, while the base material ensures excellent skin roughness resistance and cracking resistance,
They obtained the knowledge that it has a significantly long service life in practical use.

This invention was made based on the above knowledge, and the reason why the component composition was limited as described above will be explained below.

A. The 3a VC component of VC has 1. itself has a micro Vickers hardness of 2
Since it has a high hardness of 940, it has the effect of significantly improving the wear resistance of the member, but if the content of a is less than 2%, the desired wear resistance cannot be secured; If the content exceeds that amount, the toughness of the member will drop sharply, so the content m is determined to be 2 to 20% in proportion to the entire member.

B. Content of metal carbon and nitride m These components also have high hardness like VC, so
It has the effect of improving the wear resistance and oxidation resistance of parts, but if the m content is less than 2%, the desired effects cannot be obtained, while if the m content exceeds 20%, the toughness Therefore, the content of M was determined to be 2 to 20% in terms of the proportion of the entire member. In addition, in the carbon and nitride of these metals, the micro-Gokkers hardness is
TiN is 2450. Ti Co, 25 No, 7 (
, has a high hardness of 2840, and "CO,84" 0.11 has a high hardness of 3200, and is an inexpensive component, so it is particularly desirable to include these components.

Composition of C8 matrix (a) C The C component contains Cr, W, and Mo, which are solid solutions in the matrix to increase its hardness, as well as other alloying components.

and V, etc., to form mainly Ms C-type carbide, which has the effect of increasing the room temperature and high temperature strength of the member and improving the wear resistance.
．． If the content is less than 5%, the desired effect cannot be obtained, while if the content exceeds 5%, the toughness of the member will decrease.
It was set at ~5%.

(b) Cr A part of the Cr component dissolves in the base material to improve the corrosion resistance and hardenability of the member, and the remaining part forms carbide as described above, improving the wear resistance of the member. However, if the content is less than 3%, the desired effect cannot be obtained, while if the content exceeds 10%, the impact resistance of the member will decrease. The content thereof was determined to be 3 to 10% in proportion to the base material (the same applies hereinafter).

(c) W and MO These components form carbides as described above and have the effect of improving the room temperature and high temperature strength and wear resistance of the member, but their content is W: 1 % and MO: less than 2%, the desired effect cannot be obtained in the above action, while the content is W: 10% and Mo: less than 2%, respectively.
If it exceeds 15%, the toughness of the member will decrease, so the content should be adjusted to W: 1 to 10%9MO.
: 2 to 15%.

(d) V ■ component has the effect of increasing the tempering hardenability of the base material and thereby improving the wear resistance of the member, but its content is 1%.
If the content is less than 5%, the desired wear resistance cannot be ensured, while if the content exceeds 5%, the toughness of the member will decrease, so the content was set at 1 to 5%.

(e) Ni The Ni component has the effect of improving the stress corrosion resistance of parts and thereby significantly improving the roughness resistance.
) is less than 5%, it is not possible to secure the desired excellent roughness resistance, while when the content exceeds 20%, the wear resistance of the member tends to decrease. The amount was determined to be 5-20%.

(f) C0 The C0 component has the effect of significantly improving high-temperature creep resistance (high-temperature strength) and thereby increasing the cracking resistance of the member, but if its content is less than 5%, the desired excellent cracking resistance is not achieved. On the other hand, even if the content exceeds 20%, no further improvement effect will appear, so considering economic efficiency,
Its content was set at 5-20%.

In addition, the hot wear-resistant member of the present invention is provided by first reducing a raw material powder for forming a base material, (a) oxide powder of Cr, W, Mo, V, Ni, and CO, and carbon powder, and then reducing the powder to a predetermined amount. A method that consists of blending and mixing to obtain a high-alloy steel composition, and then heating and reducing the mixed powder in a vacuum or in a hydrogen stream.

(b) A method of melting high alloy steel having a predetermined composition and atomizing the high alloy steel melt.

By method (a) or (b) above! Next, VC powder and metal carbon/nitride powder are blended into a predetermined composition, and this is wet-pulverized and mixed to form a mixed powder. 9/-
The green compact is press-molded at a pressure of With the powder compact given a predetermined shape,
Sintering is performed by heating and holding at a temperature of 1200 to 1300°C in a vacuum or hydrogen atmosphere, followed by heating temperature: 1200 to 1300°C, pressure crab 500 to 200°C as necessary.
Hot isostatic pressing was carried out under the conditions of 0 atmospheric pressure, and finally using a salt bath, quenching temperature: 1200 ° C, tempering temperature:
It can be manufactured by performing heat treatment under conditions of 560 to 580°C.

〔Example〕

Next, the hot wear-resistant member of the present invention will be specifically explained using examples.

0.2 to 0.7 in order to produce raw material powder for base formation.
Or, W with an average particle size in the range of μm.

Oxide powders of Mo, V, Ni, Go, and Fe and carbon powder were prepared, and after blending and mixing these powders into a predetermined composition, the mixture was heated at a temperature of 1150°C for 30 minutes in a hydrogen stream.
By carrying out reduction treatment under the conditions of time holding, raw material powders for forming a base material having the component compositions shown in Table 1 and having an average particle size within the range of 1 to 10 μm are produced, and then, as a result of the Using the obtained raw material powders for forming bases of camphor, VC powders each having an average particle size within the H curve of 3 to 15 μm17), and carbon/nitride powders of various metals, these raw material powders were The composition shown in the table was mixed, mixed 24 hours a day in a ball mill, dried, and then subjected to reduction annealing in a hydrogen gas atmosphere at a temperature of 900°C for 2 hours, followed by 10Xff/ The green compact is press-formed into a predetermined shape at a pressure of m, and after intermediate processing is performed on the green compact to make it into a predetermined size, it is heated to a predetermined temperature within the range of 1250 to 1280°C in a vacuum or nitrogen atmosphere for 1 hour.
Sintered under the conditions of time holding and further temperature: 1250℃,
Hot isostatic pressing is carried out under pressure crab conditions of 1000 atm.
Final temperature: After quenching from 1200℃, temperature: 58
By applying heat treatment consisting of three times of tempering treatment held at 0°C for 1 hour, the material has substantially the same composition as the blended composition, and outer diameter: 330 mφ x inner diameter: 19
Hot wire rod rolling rolls 1 to 21 of the present invention having dimensions of 0 sφ x wall thickness = 95# were manufactured, respectively.

Next, these hot wire rod rolling rolls 1 to 1 of the present invention were assembled into a steel wire heating temperature of 1000 to 1050°C.
Hot rolling was carried out for 70 hours at a rolling reduction of 15 to 25%, and after hot rolling, the maximum wear depth on the roll surface was measured and the surface texture was evaluated as 1! I guessed it. These results are also shown in Table 1. Table 1 also shows the Rockwell hardness (C scale) and transverse rupture strength. Furthermore, as a conventional hot wire rod rolling roll, C: 0.91%, Cr
: 3.9%, W: 2.01%, 1ylo: 4.
A carbide dispersion-strengthened alloy steel manufactured by casting, forging, and rolling was prepared from a molten metal having a composition of 2%, V: 3.2%, CO: 10%, Fe and unavoidable impurities: the remainder. Table 1 shows the test results of this conventional hot wire rod rolling roll under the same conditions.

〔Effect of the invention〕

From the results shown in Table 1, hot wire rod rolling rolls 1 to 21 of the present invention all have higher hardness and strength than conventional hot wire rod rolling rolls, and exhibit excellent wear resistance. Not only that, but it also has excellent surface roughness resistance and cracking resistance, so the surface of the rolled wire rod was extremely smooth until the end.

As mentioned above, the hot wear-resistant member of the present invention has all the excellent wear resistance, roughness resistance, and cracking resistance required of these members, so it is suitable for practical use. It exhibits excellent performance over an extremely long period of time.

Claims (1)

[Claims] (1) Fine vanadium carbide, nitrides and carbonitrides of group 4a and 5a metals of the periodic table, and solid solutions of two or more of these (hereinafter referred to as metal carbonitrides) are added to the base of high alloy steel. ), and the content of vanadium carbide and metal carbon/nitride is 2 to 20%, respectively, and the remaining high alloy steel The base material is one or two of C: 0.5-5%, Cr: 3-10%, W: 1-10% and Mo: 2-15%, V: 1-5%, Ni. A hot wear-resistant member made of dispersion-strengthened sintered alloy steel, characterized in that it has a composition (the above weight %) consisting of: 5 to 20% Co, 5 to 20% Co, and the remainder Fe and unavoidable impurities.