JPS5873750A - Wear resistant sintered alloy - Google Patents

Abstract

PURPOSE:To obtain a sintered alloy with superior wear resistance by spraying an alloy prepared by adding specified amounts of Cr, Mo and/or W, V and/or Nb, Co, O, and Si and/or Mn to Fe to manufacture powder, mixing the powder with a specified amount of graphite, and molding and sintering the mixture. CONSTITUTION:An alloy consisting of, by weight, 3-10% Cr, 3-20% Mo and/ or W, 0.5-10% V and/or Nb, <15.0% Co, <0.5% O, 0.5-3% Si and/or 0.1-3% Mn, <2% impurities and the balance Fe is prepared. The alloy is melted and sprayed to manufacture alloy powder, and the powder is mixed with 0.8-2wt% graphite powder. The powdered mixture is compacted and sintered to obtain a sintered alloy having >=90% density ratio and >=500Hv apparent hardness and contg. 5-20% by area of fine carbide particles having <=15mum diameter dispersed uniformly in the matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is a hard and dense sintered bond with excellent wear resistance suitable for sliding part materials used in relatively high-grade applications such as rocker arms of internal combustion engines. It's about money.

In general, in sliding conditions under high-pressure surfaces, the lubricating oil film is sufficient for wood, and sliding members used under high-pressure surfaces have high wear resistance (including scuffing resistance and ♂ scuffing resistance). I! Sliding members such as rocker arms/bases, etc., are required to have so-called high-grade metal alloys containing a large amount of alloying elements such as Cr*Me, W aV, Nb, etc., which are based on F. Since it contains a large amount of carbide-forming elements such as carbon dioxide, it is possible to uniformly precipitate fine carbides through appropriate heat treatment.1. It has a hard core that provides excellent abrasion resistance.

When producing such high-speed steel materials by powder metallurgy, it is conventional to use F@t pace alloy powder with a target composition containing the alloying elements and C as described above. However, since such alloy powder is extremely hard, it has low compressibility and formability, and when it is rounded and compacted using compression molding means such as a normal press,
It has been difficult to obtain a sintered body with excellent wear resistance because a dense powder compact and, in turn, a dense sintered body cannot be obtained. Therefore, special techniques such as hot pressing, high-temperature isostatic pressing, and hot forging must be used as compression molding means, resulting in the problem of increased manufacturing costs. Furthermore, when the above-mentioned alloy powder is manufactured by the industrially widely used spraying method, the surface of the rounded powder containing a large amount of alloying elements such as Cr, V, and Nb that cannot be combined with oxygen is significantly oxidized. If the powder is used as it is, the sintering between the powder particles' does not progress sufficiently during sintering, and therefore a hard to high-density sintered body cannot be obtained. It may be possible to pre-reduce the alloy powder obtained by the TE-fog method before compacting, but this would result in a significant increase in manufacturing costs.In order to solve the above-mentioned problems, As a measure, we have already proposed a method of separately adding and mixing Ct graphite powder to an alloy powder with a special composition containing a and p. If the sintering time is increased at a higher sintering temperature, the F-P-c eutectic structure will grow rapidly, making the alloy brittle and making it difficult to obtain a uniform and fine carbide structure. There is a problem of force.

This invention was made in view of the above circumstances, and uses a spray-produced alloy powder of high-speed steel to eliminate P.
The purpose of the present invention is to provide a sintered alloy that is dense, highly hard, has fine carbides uniformly dispersed, and has excellent wear resistance without using any special compression means such as a hot press. .

In other words, Jin's li! The sintered alloy of l1llI is a high-speed steel material O component "t' h b Cr, No/W,
V/Nb, C0゜hayu, add Si or M with a molten metal deoxidizing element to suppress the oxygen content to below t-O,S*, and produce the base metal powder by spraying, and separately from the alloy powder. The sintered alloy of this invention is a mixture obtained by adding and mixing C as graphite powder, compacting and sintering.Specifically, the sintered alloy of this invention
3.0 to 10.0%, Mo, WOI type or 2 types in total amount 3.0 to 20.01% V, Nb (DIa ma round wire 2 types in total amount 0.5 to 10.0%) 1, Co f 15
．． Contains 0 or less, 0 is 0.54 or less, and 2
810.5-3.0, Mal 0.1-3.0, 1
Using a spray-produced alloy powder containing F. or 2-, the balance being F. and impurities of 211 or less, graphite powder of 0.8 to 2.0 mm is added and mixed to the alloy powder, and the powder is compacted and The sintered alloy of the present invention will be described in more detail below.

In producing the sintered alloy fitting of the present invention, spray-produced all-gold powder containing targeted amounts of each alloying element except C is used as described above. That is, Cr is 3.0 to 10
．． 01G, Mo a W 1 type t7'ha 2 types total amount -1"3.0~20.01i, v, Ntolmt or 2
The total amount of seeds is 0.5 to 10.0, and the total amount of Co is 15.0.
Contains less than tatami, Oto, less than 5, SiG,
5-3.0'II, Mu 0.1-3.011 of 1
seed! An alloy powder is used which contains two types of aluminum, the balance being F and impurities of 2.0 or less.

To explain the reasons for limiting the ranges of each component above, first, Cr #
MOa w e v e Nl) is a basic component element of 90 types of high-speed steel materials, and all of them are carbide-forming elements, and they do not only solidly dissolve in the base and strengthen the base (, It produces hard fine carbides and improves wear resistance.However, if the O range is too low, no noticeable effect will be obtained, and if the O range is too high, no further effect will be obtained. (On the contrary, the powder becomes hard and its compressibility and formability decrease. As a result, it becomes difficult to obtain a dense sintered body, and a special compression method is required for compression molding.) Therefore, the manufacturing cost is high, and the raw material cost is also high.For these reasons, Cr, M.

W e V = Nb can be limited to the above-mentioned O range, and among these alloying elements, V and Nb also have the effect of grain refinement and carbide refinement, and Cr.

Among the above-mentioned component ranges for Mo79 and V/Nk, the optimum range for Cr is 3.0 to 8.0, and the total amount of Me/%' is 5.0 to 15.0. The optimum ratio is 1.0 to 5.0 in total for V/Nb.

Co dissolves in the base and strengthens the base, and also improves the bonding between the generated carbide and the matrix and cox, contributing to improved wear resistance. However, if it is added in excess of 15.0 It is not a stupid 9 that does not increase the effect any further, but on the contrary it reduces the hardness of the matrix and increases the strike height, so 1
5 or less, more preferably 10.01 or less.81 is a written element that reduces forgeability and rollability in the case of ingot material, coarsens carbides, and reduces hardenability.
Normally, it is suppressed to 4 or less, but in the case of sintered alloys, since forging and rolling are not performed, there is no adverse effect, and on the contrary, by adding St, O molten metal is deamed during production of alloy powder! Effective and ah. That is, in this invention, Cr,
An alloy powder containing a large amount of components that easily combine with oxygen, such as V and Nb, is manufactured by the spray method (Atomize method). :, A/C, the surface of the alloy powder obtained in this case is easily oxidized, but as mentioned above, 8
By adding 1, oxidation is prevented during the production of alloy powder containing alloy components that are more likely to combine with oxygen.
As a result, the bonding (sintering) between the alloy powders during sintering is less likely to be inhibited by the oxide film, and the sintering properties are good, increasing the hardness and density, and making the sintered body more durable. It becomes possible to obtain AK.

However, if the amount of 8i is less than O,S*, the above-mentioned effect will hardly be obtained, and if it exceeds 3,0, the above-mentioned effect will not increase any further. Since the harm caused by the lowering force is large, it is limited to 0.5 to 3.0 cm.
And within this range, especially the range of 810.5 to 2.0
I like it.

Mu is molten metal C0JIG like 8 quantity! It has an effect on Shun;
Therefore, it is effective in preventing powder oxidation during production of alloy powder and improving sinterability], and is also effective in improving the hardenability of tX, matrix, and steel. However, if the amount of Mo is less than 0.111L, these 0 effects cannot be obtained, and conversely, even if more than 3.011L is added, these effects will not increase, but the powder will harden and molding will be difficult. It is limited to 0.1 to 3.0 because the negative effects of thicken become more difficult. Within this range, 0.5 to 2.0- is preferable. ・0 means that most of it is in the form of oxides on the surface of the alloy powder □□□
As mentioned above, this surface oxidation flow line occurs during sintering, inhibits the sintering of the alloy powder, slows down the progress of sintering, and creates a sintered body with high hardness and high density. gain more,
41. In this invention, the alloy powder is obtained by the atomization method, which contains a large amount of oxidizing elements such as Ore Va Nb, and which easily causes oxidation of the powder.The influence of the above cannot be ignored. Therefore, in this invention, as mentioned above, an appropriate amount of molten metal deoxidizing elements si, /l, or Ms is added to suppress ott.

The above-mentioned negative effects caused by 0 become sharply noticeable when the 0 content exceeds 0.5, so it is usually suppressed to below 0.5, preferably below 0 and a.

In this invention, C is mixed as graphite powder into an alloy powder having the above-mentioned composition range, which is produced by a spray production method such as a water atomization method or a spread atomization method. This C reduces oxides on the surface of the alloy powder during sintering and promotes sintering between the alloy powder particles, or dissolves solidly in the matrix to strengthen it, and also contains Cr, Mo,
It forms carbides with W, V, and Nb and contributes to improving wear resistance. If C is included in the alloy powder, as mentioned above, it will not be effective in reducing oxides on the surface of the alloy powder, and it will also make the alloy powder extremely hard and deteriorate the compressibility and formability of the alloy powder. let If the amount of C added is less than 0.8, the above-mentioned effects will hardly be obtained, while if the amount of C exceeds 260, the carbide will become coarse and the wear resistance will deteriorate. Addition amount of C Ho, s~2. , O vomit, preferably 1. 'O ~ 1.8 regret.

The particle size of the alloy powder used is preferably about -100 mesh, and optimally about -200 mesh.
Also, the particle size of the graphite powder that is mixed separately as C is an average particle!
! When mixing the powder, which is preferably about 10 am or less, a lubricant such as zinc stearate is usually mixed as necessary.

As described above, the mixed powder consisting of alloy powder, graphite, and a lubricant added as necessary is compression-molded into a desired O-shape by an appropriate compression means.

As for this compression means, as in the conventional case, high temperature hydrostatic pressure a
There is no need to apply special measures such as 04I (HIP). In other words, since C is added as graphite powder separately from the alloy powder as described above, the alloying element either does not substantially contain C or contains C. A soft material with a very small amount is used, and therefore has good pressure and formability, so the compression force during compaction can be relatively small.Furthermore, SiAm, a deoxidizing element, is added to the alloy powder. The surface oxides are suppressed to a small amount, and the sinterability is significantly improved because the oxides are reduced during p-sintering by the graphite powder added separately from the alloy powder. Therefore, a sufficiently dense and hard sintered body can be obtained.

The compacted compact is preferably sintered at a temperature of 1150 to 1250° in a non-oxidizing atmosphere containing N2.
℃, more preferably 30℃ to about 1180 to 1230℃
It is enough to heat it for about 180 minutes and perform 7 steps, and after sintering it is 8 to 180 minutes.
b Set the base to Bainite or "1" Siltenside.

Of course, if necessary, it is also possible to add heat treatment such as quenching and tempering after sintering to adjust the material to a predetermined quality.

Examples and comparative examples of this invention are described below.

Example l Cr3.011. Mo2.0%, Wl, OIG, Vo,
51G.

810.5 excellent, Mwa Q, 1 fluent, remainder practically F
・An alloy powder with an oxygen content of 0.211 was produced by a water atomization method, and after being sieved into -200 sieves and sieves,
1.4'3 g of graphite powder and 1.0 g of lubricant were added and mixed, and granulated to -42 mesh, 6.5 ton/s+
” After compacting with O compression force, N2 is
Sintered at 150°C for 60 minutes, Fa-3% Cr-2
o-1嗟W-0,5*V-0,5'A Si-0,1l
A sintered alloy of lMn-1,2C was obtained.

Example 2 Cr 4. O ring-Mo 5.04 e W 6. O
% -V 2.0 Sorry eCo 5.01, 811.0
m, the balance being essentially Fa and oxygen content of 0.2 4. Produce the alloy powder by water a) Maize method, ★ mixing graphite powder and lubricant 1 granulating and compacting in the same manner as in Example 1. After the destination.

Sintered at 1220℃ for 60 minutes in a N2f gas flow to obtain F・-4
*Cr-51!1Mo-611W-21GV-511C
A sintered alloy named Cr-51j1-1.2C was obtained.

Example 3 Cr 4.09b, Mo 5.01 *ws, o*
, N2.091.

An alloy powder containing 10.0% Co, 811.0%, 0.5% Nb, and the remainder substantially F and 0.2tlI oxygen was produced by a water atomization method, and after sieving to -200 mesh, graphite was added. After adding and mixing 1.2% of the powder and 1.0% of the lubricant and forming and compacting in the same manner as in Example 1, N was sintered at 1230°C in a gas flow to form Fs-
41Cr-51Mo-61W-21V-1091Co-
A sintered alloy with the following composition was obtained: 1.5i-o, so-Nb-1,0C. Example 4 Cr 6.0%, Mo 8.0m, w'to*
, Vl o, o.

An alloy powder containing 813.0% Mn, 2.0% Mn, the balance substantially F and an oxygen content of 0.31 was produced by a water atomization method, and the sieve content on a -200 mesh was 1.7% graphite powder and 1.7% Mn. Example 1 by adding and mixing lubricant 1.0 or more
After granulation and compaction in the same manner as above, N was sintered at 1230°C in a gas stream to form Fa-61Cr-ss''M
o-4'1kW-101V-3'1G81-2 Sorry Mn-
A sintered alloy having a composition of 1,511C was obtained.

Example 5 Cr 10. OIG, Me 8.011, N4.
01G, N2. O I regret it.

Co15.0%, Mn3.011. Nb10.01! ,
An alloy powder with the remainder substantially F and an oxygen content of 0.3 was produced by a water atomization method, sieved to -200 mesh, and then mixed with graphite powder 2. O* and lubricant 1.0 ml were mixed, granulated and compacted in the same manner as in Example 1, and then N,
is sintered at 1250℃ in a gas flow to produce F・-1011C.
r-8 Mo-4 W-21V-15 Co-31Co
A phosphorus-free alloy with a composition of -3l1Nb-1,8C was obtained.Example 6 Cr4.0*, Mo12.01. N8.011-N6.
O I regret it.

8 (2,0'A * Mn 1.0 reference, Nb 4.
01G - An alloy powder with a balance of substantially F and an oxygen content of 0.3 was produced by a water atomization method, and -200 mesh was sieved with 2.2 g of graphite powder and 1 G of lubricant added and mixed. , After granulation and compaction in the same manner as in Example 1,
Sintered at 1250°C for 60 minutes in a N gas flow to obtain
4 Cr -121GMo -sarrogancew-6mV-248
1-111M! l-41! A sintered alloy called Nb was obtained.

Comparative Example I Iron powder, F・-Cr alloy powder, F・-Mo alloy powder, F・-W were used to have the same composition as Example 2 except that St was omitted.
Alloy powder, F・-7 alloy powder 111, Co powder, and graphite powder were mixed together, and tc# lubricant jll-1 and OIG were added.
Sorry Ml -6 Yu W-21V-591Co -1,29I
Comparative Example 2 A sintered alloy was obtained with a composition in which Sl was removed from the alloy powder of Example 2, and the oxygen content was 0.
．． 3- alloy powder, namely Cr4.0, Mo
5.0 regret'-' W 6.0 * e V 2. O'
Same as Example 2 except that 4-Co 5.04 e Ci-44-1 alloy powder with substantially F function and oxygen content of 0,391 was produced by water atomization method, and graphite powder was not added. F・-41ICr-5, Sorry Mo
-61W-21V-5 (A sintered alloy with a composition of q-1,0IC was obtained. :□・Comparative Example 3.
``''''''''Composition extracted from the alloy powder of Example 2 (alloy powder with a Dllll amount of 0.6, that is, Cr 4.0 Me 5.04-W 6.0
An alloy powder containing substantially 2 F and an oxygen content of 06% was produced by a water atomization method, and then Fs- was produced in the same manner as in Example 2.
41Cr-! S1'Mo-61! W-211V-511
A sintered alloy having a composition of Co-1,01IC was obtained.

Comparative Example 4 The oxygen content of the composition obtained by removing Mu from the alloy powder of Example 50 is 0.
81e) Alloy powder, i.e. Cr 10.0% a
Mo8.01, W4.01G,, V2.01,
Co15.011, Nb10.01. An alloy powder containing substantially F and an oxygen content of 0.8 was produced by the water atomization method, and F@-1 was prepared in the same manner as in Example 5.
(NICr-811Ma-41W-2*V-1511C
A sintered alloy having a composition of o -101Nb -1,611C was obtained.

The sintered body properties of the sintered alloys of Examples 1 to 6 and Comparative Examples 1 to 4, that is, the apparent hardness, density ratio, and 1.

(ratio to true density), ・Table 1 shows the measurement results for the maximum particle diameter of carbides and the area ratio of carbides.・Furthermore, with these sintered alloys, the ay car -Muno R1 was prototyped and combined with a low-alloy chill cam, the spring load was increased by 5096 than the normal load, and the speed was 2000 rpm, 30
A 0-hour acceleration condition durability evaluation test was conducted to find the maximum wear on the mouth, cam arm pad, and do, and the maximum wear on the cam major diameter (tt-).
The results were also shown in Table 1. In Fig. 1, 2 indicates the rocker arm and 3 indicates the other party's cam.
As is clear from the table, all of the sintered alloys according to Examples 1 to 6 of the present invention have an apparent hardness Hma (10 o'clock) of 500 or more, a density ratio of 90 or more, and carbide particles of 15 μm or less. are uniformly dispersed in the matrix with an area ratio of 5 to 25. The durability test results also show that the amount of wear on the elbow was less than 20 μm and the amount of wear on the cam cover was less than 100 μm, which was extremely low, and it is clear that the wear resistance was extremely good.

On the other hand, Comparative Example 1 has the same composition as Example 2 except that 8i is omitted, but due to the addition of each alloying element Xt-ferroalloy powder, the diffusion of each element into the iron base is different from the opaque component. As a result, sintering does not proceed sufficiently, resulting in low hardness and density, and in addition, carbides and formed elements are unevenly distributed in the compact, resulting in 6゛''EC, b''''1' ′″′
"'-...,, o 4 (2)""-゛ゞ.

As a result, wear resistance is low and the mating material is also worn out.

Comparative Example 2 used an alloy powder with almost the same composition as Example 2, except that Si mirror was included. Since it was included in the 0% alloy powder, the amount of oxygen in the powder itself was low, but the powder was significantly hardened. As a result, sintering does not progress sufficiently due to factors such as poor compressibility and formability in the powder compaction process, and lack of reducing action by graphite powder during sintering, resulting in hardness. Both the thickness and density are lower than those of the embodiments of the present invention. However, compared to Comparative Example 1, the use of alloy powder does not cause insufficient diffusion of each component element, so the carbides are uniformly and finely dispersed9, and the wear resistance is the same as Comparative Example 1!・In addition, in Comparative Examples 1 and 2, the temperature was 1250°C in order to sinter sufficiently.
Experiments conducted by the present inventors have confirmed that there is a need for sintering at higher temperatures for a considerable length of time.

Comparative Example 3 used alloy powder with the same composition as the example except that stt was omitted; □ was used, and tqc was also separately added and mixed. Due to insufficient deoxidation, the oxygen content of the alloy powder was as high as 0.6 (
As a result, sintering progressed insufficiently, and the hardness and density were lower than in Example 2. Furthermore, carbides are formed in a concentrated manner in areas where oxides on the powder surface have been reduced during sintering, and as a result, large-diameter carbides are unevenly distributed, and the wear resistance is also lower than in Example 2.

Furthermore, in Comparative Example 4, an alloy powder having the same composition as in Example 5 was used except that Mu was omitted, and C was also added separately, but in this case as well, the deoxidation of the molten metal was The amount of oxygen in the alloy powder was as high as 0.8, which was insufficient, resulting in low hardness, low density, and low wear resistance as in Comparative Example 4.

As is clear from the above explanation, the sintered alloy of the present invention has C
By adding and mixing C as a graphite powder separately with the high-speed steel alloy powder, in other words, by using an alloy powder that does not substantially contain C or even if it does contain it, it is possible to form an alloy. It improves the compressibility and formability of the powder so that a dense compacted body can be obtained, and as a raw material alloy powder - 11 of the alloying elements of high speed steel series, 81 and/or effective for deoxidizing molten metal. Using an alloy powder containing Mnt and suppressing the oxygen content to a small amount (0.5 tatami or less), that is, an alloy powder with few oxides on the surface, and then sintering with graphite powder separately added and mixed as described above. At the time of sintering, the oxides on the surface of the alloy powder are reduced, and due to the overall effect of these elements, the mutual sinterability of the powder particles is improved during sintering, and carbides are formed finely and uniformly. Therefore, according to the present invention, it is possible to produce an alloy powder without adding P, without requiring special compression techniques such as hot pressing1, and without requiring preliminary reduction treatment of alloy powder. , low cost, high hardness, high 1! It has now become possible to obtain a sintered alloy that is Fjf and has high wear resistance.

[Brief explanation of the drawing]

Figure 1 shows the use of the sintered alloy of this invention.
This is a schematic front view showing an example of the vicinity of Tsudo. Applicant: Tosoyu Automobile Industry Co., Ltd. (and 1 other person) Agent: Patent attorney Takehito Toyota (and 1 other person)

Claims (2)

[Claims] (1) Cr: 3.0-10.01 (weight 9, same below) Me, W (D 1811 *Id) Total amount of 2 types: 3.0-20.0, V, MO 1 type or 2 Total amount of seeds"t'0.5~10.0, C・'i15.0
Contains 0, o and s tatami, respectively, and 510
．． ．． Using a spray-produced alloy powder containing 5 to B, O, and MnO, 1' to 3.0 and 1 or 2 types, the balance being Fa and 2 or less impurities, 4. A wear-resistant sintered alloy, characterized in that it is obtained by adding and mixing graphite powder of 0.8 to 2.0 to an alloy powder, compacting it, and sintering it. (2) Density ratio is 90 or more and apparent hardness H is 500
The wear-resistant sintered alloy according to claim 1, wherein fine carbide particles having a p1 diameter of 15 mm or less are uniformly dispersed in the matrix at an area ratio of 5 to 2011 G.