JPS62167862A - Wear resistant steel - Google Patents

Abstract

PURPOSE:To obtain a wear resistant steel having superior strength, toughness and wear resistance and preventing the scratch of an opposite material by adding prescribed percentages of C, Si, Mn, Cr, Ni, Mo, W, V, Ti and B. CONSTITUTION:This wear resistant steel consists of, by weight, 1.2-3.0% C, <=1.0% Si, <=1.0% Mn, 12.0-27.0% Cr, 0.1-3.0% Ni, 0.7-1.5% Mo, 0.5-1.5% W, 0.5-1.0% V, 0.20-0.50% S and the balance Fe with impurities. The steel is refined as usual but ordinary hardening and tempering are preferably carried out after casting, softening annealing and mechanical working so as to provide desired performance. The wear resistant steel is suitable for use as a material for members of a hot rolling mill.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention has good strength and toughness, and is particularly excellent in wear resistance, and furthermore, it minimizes the possibility of single scratches on contacting mating members. The present invention relates to a wear-resistant steel suitable for use as a hot rolling equipment member.

Background technology Generally, in metal hot rolling equipment, rolling rolls,
Various guides (especially important for bar and profile rolling equipment)
, conveyance/guide rollers, and other members are indispensable, but it goes without saying that these members are required to have sufficient strength and toughness because they are constantly in contact with the moving, high-temperature rolled material. , having excellent wear resistance is also considered to be an extremely important requirement.

Therefore, wear-resistant cast iron, ductile cast iron, carbon steel equivalent to 545C specified by JIS, etc. have traditionally been used as materials for such hot rolling equipment components, but in recent years, the mainstream has been 5KD11 (5KD11), which has even higher performance. JIS standard) equivalent alloy steel and alloy steel called "Tranchinil-ni 1" (product name) (weight percentage: C: 1.00-1.70%, S
l: 2.00% or less, Mn: 2.00% or less, Cr:
There has been a shift towards those containing 10.00 to 15.00% and Mo: about 0.50%.

However, in recent years, metal hot rolling operations have been showing a tendency to become faster and faster, and materials for hot rolling equipment components are required to have the above-mentioned properties, especially wear resistance. Further improvements have been earnestly desired, and there are strong expectations for the emergence of materials that also have the property of being difficult to cause defects on the rolled material that comes into contact with the material. Even steels equivalent to Neil A 1'' and 5KDII could not fully meet these demands.

<Means for Solving the Problems> From the above-mentioned viewpoints, the present inventors have found that sufficient strength and toughness can be ensured with only general heat treatment next to casting, and that As a result of our research, we have developed a steel equivalent to 1# and 5KDII that also exhibits even better wear resistance, with the aim of providing a steel with sufficient performance to be applied to rolling equipment components, etc. , below (a) to (
The findings shown in c) were obtained. That is, (a) the above-mentioned ``trantine A1'' and 5KDII
The reason why the wear resistance of comparable steels cannot fully meet recent demands is that even though the quenching and tempering treatments applied to these materials during product manufacturing do not completely transform the structure into martensite, This is because some ferrite phase (approximately 20 capacitance) appears, and unless the appearance of this ferrite phase is suppressed and a complete martensitic structure is achieved, no further improvement in wear resistance can be expected;
(b) However, based on a steel with good wear resistance that contains a high proportion of Cr, which forms composite carbides and improves the hardenability of the steel, appropriate amounts of N1 and Mo are added and the amount of Mn is increased. By adjusting the
By adjusting the amounts of Ni, V, Ti, and B, the tendency for cracking to occur due to a complete martensitic structure is stably suppressed. , V , Tt
The wear resistance is further improved by the carbides formed by the steel, and in addition, the solar components are finely dispersed in the steel and play the role of a cushioning material, which reduces the contact with the other material.
(C) Therefore, steel whose composition has been adjusted as described above can be used for hot rolling rolls, various guide materials, etc. Or, when used as rolling equipment members such as conveyor rollers and guide rollers, it should exhibit excellent performance and significantly improve the quality of rolled products and the life of the equipment.

This invention is made based on the above knowledge, and the steel is made of: C: 1.2 to 3.0% (hereinafter, the component ratio is expressed as weight %), Si: 1.0% Hereinafter, Mn: 1.0% or less, Cr
: 12.0-27.0%, Ni: O, 1-3.0
%, Mo: 0.7-1.5%, W: 0.5
-1.5%, V: 0.5-1.0%, Ti: 0.05-0.50%, B: 0.20-0.50%, and the remainder is Fe and impurities. It is characterized by having extremely excellent abrasion resistance and ability to prevent eaves from contacting other materials by configuring it with a component composition consisting of the following.

The steel of this invention is produced by a normal method, but in order to exhibit the desired performance, it must be subjected to softening annealing (to facilitate machining) following casting and after machining. , it is preferable to perform general quenching and tempering treatments.

Next, the reason why the component composition of the wear-resistant steel of the present invention is limited as described above will be explained.

■C The C component has the effect of forming high hardness carbides together with Cr, W, etc. and improving the wear resistance of steel, but if its content is less than 1.2%, the desired effect will not be achieved. On the other hand, if the content exceeds 3.0%, there is a risk of cracking due to heat effects, so the C content should be 1.
．． It was set at 2 to 3.0%.

Note that it is preferable to adjust the C content to 1.8% or more.

■ 5i The S1 component is necessary for ensuring flowability and deoxidizing during casting, and even if it is in a very small amount it will have a certain effect, but if it exceeds 1.0% The S1 content was determined to be 1.0% or less because if it is contained, it will cause grain coarsening of the steel and cause deoxidization.

■ Mn In addition to acting as a deoxidizing agent for steel, the Mn component is also an effective component for forming a complete martensitic structure.
If the Mn content exceeds 1%, it will form sulfides together with S, leading to hot embrittlement of the steel.
．． It was set as 0% or less. It should be noted that Mn also exhibits a certain effect even in a very small amount, but it is recommended that Mn be contained in an amount of 0.6% or more.

■ Cr The Cr component forms a composite carbide with W and C and has the effect of improving wear resistance, but it also has a positive effect on improving wear resistance by improving the hardenability of steel. However, if the content is less than 12.0%, the desired effect cannot be obtained because the composite carbide formed will only have low hardness.
．． If the Cr content exceeds 0%, there is a risk of cracking due to heat, so the Cr content should be 12.0 to 2.
It was set at 7.0chi.

■ Ni The N1 component has the effect of preventing dendrites and improving the toughness of steel, including this effect, and improving the impact value.
Furthermore, it is an effective component for forming a complete martensitic structure, but if its content is less than 0.1%, the desired effect cannot be obtained, and on the other hand, if it is contained in an amount exceeding 3.0%. The N1 content was set at 0.1 to 3.0% because there is a risk of cracking and the hardness does not decrease even after tempering, making machining difficult.

■ MO The Mo component has the effect of improving the hardenability of steel and improving the toughness and yield point by refining grains, but if its content is less than 0.7%, the desired effect is not achieved. On the other hand, if the content exceeds 1.5%, cracks may occur, so the MOC content was set at 0.7 to 1.5%.

@ W The W component has the effect of partially combining with C to form M2O to improve wear resistance, and partially dissolved in martensite to improve tempering resistance. It also exhibits the effect of increasing high temperature strength, but its content is 0.5
If it is less than 1%, the desired effect cannot be obtained from the above action;
If the W content exceeds 5%, the effect will not be significantly improved and this will cause an economic disadvantage, so the W content should be 0.5 to 5%.
It was set at 1.5%.

■ V The V component has the effect of improving the yield point of steel, combining with C to form hard MC carbides and improving wear resistance, and also has the effect of increasing impact value. However, if the content is less than 0.54, the desired effect cannot be obtained, and on the other hand, if the content exceeds 1.0%, the toughness will deteriorate. 0.5
It is set at ~1.0%.

■ Tl The T1 component has the effect of uniformly dispersing MC type carbide (TiC) in steel and improving high temperature creep properties and wear resistance, but if its content is less than 0°05%, the above The desired effect cannot be obtained in the action, and on the other hand, if the content exceeds 0.050%, the effect will not be significantly improved and it will cause an economic disadvantage, so the T1 content should be 0.05 to 0.50%. Established.

■ B Component B has the effect of improving the toughness of steel, as well as the effect of improving heat resistance, thermal conductivity, and corrosion resistance, and further acts as a buffer material when finely dispersed in the steel. It is something. Therefore, based on this action as a buffer material, the lubricity with the contacting member and the "prevention of scratches" on the contacting member are significantly improved.

The above-mentioned buffering effect of B is due to the fact that, from a metallographic point of view, the interatomic bonding force of B in the α-axis direction (between layers) is much weaker than the interatomic bonding force in the C-axis direction (intralayers). This is due to the fact that when shearing force is applied, the bonds between the layers are broken and crystals tend to form interosseous structures. Although this effect is common to solid lubricants such as molybdenum disulfide and graphite, it also has a positive effect when added to steel as an alloying element, and can also be used as a buffer material even when heated to over 500℃. The effect of B is outstanding in that it does not impair the functions of.

However, if the B content is less than 0.20 inches, the effect based on the above action is not sufficient, and in particular, only steel can be obtained that is unsatisfactory in terms of the preventive effect of seizure with contact members and the preventive effect of eaves on the contact members. do not have. On the other hand, even if B is contained in an amount exceeding 0.50%, the above-mentioned effects will not be significantly improved or the rigidity will be adversely affected. For this reason, the B content was limited to 0.20 to 0.50%.

Next, the present invention will be explained using Examples and comparing with Comparative Examples.

〈Example〉 First, steel having the composition shown in Table 1 is melted by a normal method, and after casting it into a mold and paring the mold, the steel is melted by a conventional method to facilitate machining. Annealing (8
60°C x 10hr), machining (turning), quenching (10
After 50℃X A hr, forced air cooling), tempering to 470
℃×4 hr) and surface polishing, outer diameter: 6
011. Diameter of groove valley = 5ON, length = 35mm and groove width:
A 201 ul guide roller for round bar conditioning rolling equipment having the shape shown in FIG. 1 was manufactured. It should be noted that for comparative materials R and S, it is no secret that the above heat treatments were omitted.

Next, the surface hardness (Shore hardness: Hs) of the obtained guide rollers was measured, and the guide rollers were subjected to a drag test to compare the wear resistance properties.

In the friction test, as shown in Fig. 2, a SUS304 stainless steel round bar 2 (surface hardness: Hs40) with a diameter of 13 mm was pressed against a rotating sample guide roller 1 at a load (W) of 25 kg and a friction speed: The test was carried out by measuring the width of the wear marks generated on the surface of the sample guide roller 1 after contacting without lubrication under the conditions of 1 m/cross and friction distance: Loom.

The obtained results are also shown in Table 1.

As is clear from the results shown in Table 1, it can be seen that the steel of the present invention has significantly superior wear resistance compared to the comparative materials. Actual operational tests showed that the guide roller made of the steel of the present invention was 22 to 30 times as much as the guide roller made of ductile cast iron, and 5 to 3 times that of the guide roller made of chilled cast iron.
It was confirmed that the service life of the roller is 6 times longer than that of a steel guide roller equivalent to 5KD11.

In addition, FIG. 3 is a micrograph showing the casting structure of the invention steel A in Table 1, and FIG. 4 is a micrograph showing the quenching and
This is a micrograph showing the tempered structure, and the material in Figure 4 is (FeCr) C5, and the base is martensite, which has been tempered and ε carbide precipitated. It is clear that the steel of the present invention can stably realize a hard structure free of ferrite phase by simply subjecting it to extremely common quenching and tempering treatments.

Furthermore, FIG. 5 is a graph showing the results of friction tests conducted with various friction loads (W) on the invention steel A, comparative material 0, comparative material R, and comparative material S. The results were conducted under the same conditions as those used to obtain the results in Table 1, except that the friction load was changed, and from this Figure 5, it can be seen that as the friction load increases, the steel of the present invention becomes more resistant to the comparison material than the comparison material. It can be seen that its excellent wear resistance properties become more noticeable.

In addition, FIG. 6 shows the present invention steel B and comparative material Q in Table 1.
3 is a graph showing the relationship between the friction test time and the wear width. The friction test conditions at this time were: Round bar material for pressing: Cr-Mo steel with a diameter of 13 mm (surface hardness: Hs80), Friction speed: 20 m/type, Friction load: 10 kg, No lubricant was used. Met. FIG. 6 shows that as the usage time increases, the superior wear resistance and characteristics of the steel of the present invention become more noticeable compared to the comparative materials.

Through these tests, it was also confirmed that the steel of the present invention has an excellent ability to prevent seizure with the material it comes into contact with and an excellent ability to prevent scratches on the material it comes into contact with.

Overall Effect> As explained above, according to the present invention, excellent strength,
It is possible to obtain wear-resistant steel that has toughness, wear resistance, and ability to prevent scratches on mating materials, and is suitable for round bar rolling equipment components for reinforcing bars, aluminum wire manufacturing equipment components, special steel bar rolling equipment components, and various types. When applied to material rolling equipment components, etc., it is possible to significantly improve equipment life and product quality, resulting in extremely useful industrial effects.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view of the idle roller for round bar conditioning rolling equipment manufactured in the example, Fig. 2 is a schematic diagram showing the outline of the friction test, and Fig. 3 is a casting of the steel of the present invention. Fig. 4 is a metallurgical microscopic photograph showing an example of the microstructure of the steel of the present invention after quenching and tempering. Comparative Diagram FIG. 6 is a diagram comparing the relationship between friction test time and wear scar width for the steel of the present invention and the comparison material. In the drawings: 1... Test guide roller, 2... Round bar.

Claims (1)

[Claims] In terms of weight percentage, C: 1.2 to 3.0%, Si: 1.0% or less, Mn: 1
．． 0% or less, Cr: 12.0-27.0%, Ni: 0.
1-3.0%, Mo: 0.7-1.5%, W: 0.5-
1.5%, V: 0.5-1.0%, Ti: 0.05-0
．． 50%, B: 0.20 to 0.50%, and the remainder consists of Fe and impurities.