DE1288791B - Use of a cemented carbide alloy for machining cast iron and steel - Google Patents

Description

1 2

Sintered hard metal alloys usually consist of an unusually fine grain. This is great

Essentially of tungsten carbide and titanium carbide importance for achieving the desired valuable

(with or without content of tantalum and / or niobium properties with regard to the cutting ability of the

carbide) and a binding metal such as cobalt and / or alloy during machining. For this purpose, the

Nickel, with the carbides, the y phase and the bond size 5 being within such a range,

metal form the / S phase. that the coercive force, which is easily measurable, is not

It has now been found that their material additions are less than 200 and preferably not less than

composition according to alloys known per se is 220 Oersted, at least if the binder phase

with 60 to 80 percent by volume tungsten carbide, 10 to is mainly formed by Co. In the 25% titanium carbide, 0 to 20% tantalum carbide, niobium usually the grain size should have such a value

carbide and / or vanadium carbide, 0 to 10% chromium, that the coercive force 230 to 330 Oer

carbide, zirconium carbide and / or hafnium carbide, sted.

0 to 5% molybdenum and / or molybdenum carbide, the remainder It is generally known that the coercive force increases

at least 7.5 percent by volume of cobalt and / or nickel to the grain size of the carbide grains in a sintered and optionally also iron, the total hard metal behaving in such a way that a reduction

amount of cobalt, nickel and iron 9.5% not the grain size to an increase in the coercive force

exceeds and the iron content is not higher than leads, and vice versa. It is therefore possible to use the

6% is, as a material for machining, both of the casting coercive force for determining the grain size

Both iron and steel are particularly suitable. There is evidence of this general rule the mean grain size of the carbide grains 20 agreed with deviations. A large amount of Fe in the

less than 1.6 microns, preferably less than the binder metal phase, reduces the coercive force,

1.5 microns, and at the same time the alloy in the while some complex carbides as 97 phase the

Is made so that they increase 37.5 percent by volume coercive force. Ni can also deviate

± 7.5 y-phase (carbide solid solution), 8.5 ± 1% of this rule.

/ Ϊ-phase (binder metal), while the rest in 35 The alloy according to the invention can achieve the same properties, which are mainly superior to α-phase (tungsten carbide), even if stands, with insignificant amounts of one or more Co in whole or in part is replaced by Ni or, if additional phases, such as ^ -phase are also present, Co and / or Ni are partially substituted by Fe. As mentioned, a characteristic property of the alloy to be used according to the invention is to be carried out only to the extent that the ß-phase is face-centered in that it has a very fine-grain structure in a cubic and / or hexagonal, densely packed lattice connection with the has called phase distribution. maintains. Furthermore, the grain size should be the grain size. as TiC, TaC, NbC, VC, ZrC and 35 speak, whereby the composition and the HfC is composed and in solid solution a phase structure is otherwise the same and the latter contains a not insignificant part of WC. The / S-phase alloy has a grain size such that the coercion is a binding metal phase which, for example, holds a Co entive force of at least 200 and preferably at least, while the phase consists of pure WC is 220 Oersted. The determination of the grain size and possibly a small proportion of Mo in solid 40 in those alloys in which Co, as mentioned, contains solution. In addition, smaller amounts can be completely or partially substituted, which means that other phases can occur, e.g. B. one made of Mo ₂ C be that the structure of these alloys in a standing phase. Light or electron microscope with the structure. Particularly good results were obtained when those of an above-mentioned alloy are compared, the y-phase in percent by volume was 40 ± 5%. It was found 45 Co or Co and at most 0.5 volume percent Ni that the ß-phase contains a face-centered or Fe in the binder metal phase, cubic and / or hexagonal close-packed crystal in order to have the desired qualities in terms of the lattice. Therefore, in order to achieve wear resistance and toughness, the binder metal should moderately contain a larger proportion of Co and / or, as mentioned, the alloy according to the invention must contain Ni. The binder metal can also contain Fe, taking into account the relatively high content, the Co and / or Ni being unusually fine-grained, partly due to Fe in the y phase. The mean ones are substituted, preferably up to a grain size of the carbide grains, should therefore be less than 1.6 misolches, so that the binder metal phase is not crowned, and preferably less than 1.5 microns. As the aforementioned face-centered-cubic and / or hexa-lower limit, 0.5 micron can be mentioned, gonally close-packed grating loses. Normally, the mean grain size should be within the range of 0.7 to 1.4 microns for those skilled in the art. For difficulties, the aforementioned narrow phases of certain very tough grades, the range from 0.8 ranges to achieve in the manufacture of the alloy to 1.2 microns has proven to be particularly suitable, since the characteristic features of the alloy and the stoichiometric composition of the The structure of the structure is precisely defined and in a known manner is of course also important for achieving the desired characteristic of the sintering temperature, the duration of the sintering shaft. This co-operation and the properties of the starting material is dependent on the rials for the production within the aforementioned limits. Choosing. The content of WC in percent by volume should therefore not form part of the invention, therefore within the range of 60 to 80%. 65 As a rule, the inner range from 65 to Apart from the aforementioned ratio between the 75% has proven to be particularly suitable. The alloy phases should, as mentioned, have a grain structure of 10 to 25, preferably 15 to 25, by volume which, with regard to this phase ratio, should contain TiC as a percentage. The alloy can also be up to

Contains 20 percent by volume TaC ₅ NbC and / or VC. If it contains only TaC and / or NbC, the content of these alloying elements should normally not exceed 15%. The alloy preferably contains a relatively small amount, namely 0.5 to 10% TaC and / or NbC. In addition, the alloy can contain up to 10 percent by volume Cr ₂ C ₃ , ZrC and / or HfC and up to 5% Mo. The Mo converts at least partially to carbide, such as Mo ₃ C ₂ and MoC, when the alloy is sintered. In this connection it can be mentioned that small amounts of Mo can form a solid solution in the phase, which consists of WC. The Co and / or Ni content should be at most 9.5 percent by volume. As mentioned, these can be partially substituted by Fe, but only to the extent that the binder metal phase does not lose its face-centered cubic and / or hexagonal, densely packed lattice. The Fe content should not exceed 6 percent by volume and the total Co and / or Ni and Fe content should be 9.5 percent by volume. Usually the Fe content is at most 1 or 0.5 volume percent. The content of binding metal, which consists entirely or to a large extent of Co and / or Ni with or without a certain part of Fe, should be at least 7.5 and at most 9.5 percent by volume. The range from 8 to 9 percent by volume has proven particularly suitable.

To the aforementioned surprising improvement in cutting ability both for cast iron and for To achieve steel, the alloy must have the composition given above. The structure of the Alloy with regard to the phase composition and the grain size are decisive for the result Meaning, and it must also be the ones given above in this context Conditions are met at the same time.

The following are examples of compositions and phase ratios in volume percent of two alloys according to the invention indicated:

10

TiC

(Ta, Nb) C

Co

WC

Medium grain size

Coercive force

y phase

/ 5 phase

α-phase

20.0% 1.5% 8.5% 70.0% 1.3 micron 240 Oersted 41.0% 8.5% 50.5%

22%

9% 69%

1.2 microns

260 Oersted

44%

9%

47%

Below are some comparative examples of working tests with an alloy according to the invention and with other alloys specified for the

be considered suitable for the present purpose. In the table below, column A relates to the alloy according to the invention, while the Columns B to G relate to comparative alloys. Alloys B, C, D and F are examples of alloys commonly used for machining cast iron, while the alloy E is intended for so-called universal processing, d. H. both for machining cast iron as well as steel, and alloy G is intended for machining steel. The alloy contents and the phase quantities are given in the table in Indicated by volume. It can be emphasized that alloys C and F are fine-grained, however, have a y-phase content which is only 4 or 2 percent by volume.

data

Alloys
i D

TiC

(Ta ₅ Nb) C

Co

WC

Coercive force in Oersted

y phase

^ Phase

α-phase

Medium grain size
in microns

20.0
1.5
8.5

70.0
240

41.0
8.5

50.5

1.3

5.0
9.0

86.0
190
7.0
9.0

84.0

1.9

2.5

6.5

91.0

290

4.0

6.5

89.5

1.4 3.0
10.0
87.0
180

4.5
10.0
85.5

8.1

7.0
8.0
8.5

76.5
150

24.0
8.5

67.5

2.7

1.0

10.5

88.5

270

2.0

10.5

87.5

1.0

19.0 10.0 13.0 58.0 125 50.0 13.0 37.0

2.2

With the aforementioned cemented carbide alloys 55 B e i s ρ i e 1 1

practical tests and comparisons were carried out

guided. The following report on these experiments _Λ4 . . ,,. . . _ _o

comprising the Examples 1 to 3, which is Aue to working ^matenal ^ perhtisches Gußarbeitung of cast iron refer while the examples ^sen fi ^{HB 22Ü} (Brineli-

spiel4 refers to the machining of steel. 60 hardness)

The wear resistance of the alloys was determined by the workpiece brake drum

Measuring wear on the side surface and roughing _operation

the face of the cutting insert is determined, d. H.

flank wear and scouring. From cutting speed 93 m / min.

The examples clearly show that the wear rate is 0.32 mm per revolution

strength of the alloy according to the invention in connection. "

same as the other tested alloys, a substantial 1 mm

borrowed is improved. Feed length 35 mm per workpiece

Number of workpieces .. Flank wear, mm scouring in microns

Alloy quality ABIC

20th

0.31 54

20 0.50 131

20 0.43 170 Flank wear, mm

Alloy quality A E I G

0.25 70

0.37 180

0.32 95

Example 2

Material cast iron GG 26 (after

DIN 1961)

Workpiece hub

Working method internal turning, roughed

area

Cutting speed 148 m / min.

Feed 0.2 mm per revolution

Depth of cut 3 to 5 mm

Feed length 40 mm per workpiece

Number of workpieces .. Flank wear, mm bulge in microns

Alloy quality AiB D

18 0.31 111

18 1.34 185

18 1.66 213

Example 3

Material cast iron SIS 0115

(Swedish standards)

Workpiece tube, 0 200 mm

External turning mode of operation

Feed 0.25 mm per revolution

Depth of cut 1.5 mm

Feed length 200 mm

Cutting speed,

m / min

Flank wear, mm excavation in microns cutting speed,

m / min

Flank wear, mm scouring in microns

Leg
A. agony
B. 220 220 0.42 0.62 20th 25th 240 240 0.51 0.77 25th 34

220 0.73 28

240 0.81 38

35

40

45

Example4

Material carbon steel 1 ° / ₀ C,

HB 280 (Brinell hardness)

Workpiece shaft, 0 100 mm

External turning mode of operation

Cutting speed 110 m / min.

Feed 0.45 mm per revolution

Depth of cut 1.5 mm

Feed length .... .. 750 mm

55 Scouring in microns

Claims (8)

Patent claims: 1. Use of a fine-grain, sintered hard metal alloy based on tungsten carbide, titanium carbide and auxiliary metal consisting of 60 to 80 percent by volume tungsten carbide, 10 to 25 percent by volume Titanium carbide, 0 to 20 percent by volume tantalum carbide, niobium carbide and / or vanadium carbide, 0 to 10 percent by volume chromium carbide, zirconium carbide or hafnium carbide, 0 to 5 percent by volume Molybdenum and / or molybdenum carbide, the remainder at least 7.5 percent by volume cobalt and / or nickel, optionally also iron, the The total amount of cobalt, nickel and iron does not exceed 9.5 and that of iron does not exceed 6%, provided that the mean grain size of the carbide grains is less than 1.6 microns and preferably is less than 1.5 microns and that the alloy is made to be 37.5 ± 7.5 Volume percent y-phase, 8.5 ± 1 volume percent / 3-phase contains, as a material for cutting tools for machining both cast iron and steel. 2. Use of a fine-grain, sintered hard metal alloy according to claim 1, whose y-phase is 40 ± 5.0 percent by volume, for the purpose of claim 1. 3. Use of a hard metal alloy according to claim 1 or 2, the mean grain size of the carbide grains of which is greater than 0.5 microns, for the purpose according to claim 1. 4. Use of a hard metal alloy according to one of claims 1 to 3, the content of which Tantalum carbide and / or niobium carbide is 0 to 15%, preferably 0.5 to 10%, for the purpose according to claim 1. 5. Use of a hard metal alloy according to one of claims 1 to 4, the titanium carbide content of which 15 to 25% for the purpose of claim 1. 6. Use of a hard metal alloy according to one of claims 1 to 5, the binder metal content of which 7.5 to 9.5, preferably 8 to 9%, for the purpose of claim 1. 7. Use of a hard metal alloy according to one of claims 1 to 6, the iron content of which is not more than 1.0%, for the purpose of claim 1. 8. Use of a hard metal alloy according to one of claims 1 to 7, the tungsten carbide content of which 65 to 75% for the purpose of claim 1.