AU663143B2

AU663143B2 - Method of improving the reverse bending fatigue strength of copper-base alloys

Info

Publication number: AU663143B2
Application number: AU31187/93A
Authority: AU
Inventors: Andreas Dr Bogel; Wolfgang Dr Durrschnabel
Original assignee: Wieland Werke AG
Current assignee: Wieland Werke AG
Priority date: 1992-01-17
Filing date: 1993-01-14
Publication date: 1995-09-28
Anticipated expiration: 2013-01-14
Also published as: EP0552479B1; FI104640B; DE4201065C2; FI930161A0; EP0552479A1; AU3118793A; DE4201065A1; DE59207289D1; FI930161A; JP3479919B2; JPH07166264A

Description

I- i_ 663143

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT o 0 00 0 00 ~srco 0 PrcroP PI 00 00 O 'r Applicant(s): WIELAND-WERKE AG 00 00 r

I

Invention Title: METHOD OF IMPROVING THE REVERSE BENDING FATIGUE STRENGTH OF COPPER-BASE ALLOYS The following statement is a full description of this invention, including the best method of performing it known to me/us: METHOD OF IMPROVING THE REVERSE BENDING FATIGUE STRENGTH OF COPPER-BASE ALLOYS FIELD OF THE INVENTION 00This invention relates to a method of improving the oroe reverse bending fatigue strength of wrought copper-base 0*0000 S0 alloys which are cast to an initial form and hot and/or cold worked to a final form.

BACKGROUND OF THE INVENTION For the service value of spring elements subjected t to bending stresses, the reverse bending fatigue strength of the material is a decisive criterion for the selection of the material and the design of the element.

The reverse bending fatigue strength aRB is normally determined in accordance with DIN 50 100 (fatigue test).

The reverse bending fatigue strengths reached by some of the most important spring materials are shown in Fig. 1 for example, Wieland manual "Kupferwerkstoffe", 5th edition (1986), page 235) It is the object of this invention to improve the reverse bending fatigue strength of wrought copper-base alloys as compared with wrought alloys produced by conventional methods.

SUMMARY OF THE INVENTION According to this invention, this object is accomplished by producing the initial alloy form by a 2 a ~a o ao° o o *o o o 000900 040000 0 30 a I o o o o a 6a a spray casting method and by using a copper-base alloy which contains nitride-forming elements, selected from zirconium, titanium, magnesium, chromium, aluminum, manganese, boron, niobium (columbium), tantalum, vanadium, alone or in combination, in total concentrations ranging from 0.001 to 3.0% (by weight).

Surprisingly, it has been found that for a certain class of copper :)ase alloys, the reverse bending fatigue strength of the final product can be increased by producing the original form of the initial workpiece by a spray casting method (for example, the Osprey method in accordance with British Patent 1.379.261 and British Patent 1.472.939) rather than by conventional semi or fully continuous casting methods.

The spray cast method involves atomizing a melt, solidifying the jet consisting of droplets into a billet, strip or hot rolling cake and then forming and processing these by conventional methods.

Thus, billets can be extruded to form bars, wires or tubes which may be brought into the final form by further cold forming steps if required.

Cakes can be normally hot rolled and processed to final size by subsequent cold rolling steps and intermediate anneals. For thin strips, it may be possible to skip the hot rolling operation and to start directly with the cold rolling step, similar to the procedure used for strips produced by the known continuous casting process.

According to one embodiment of the invention, a copper-base alloy is used which contains nitride-forming elements in concentrations ranging from 0.001 to Known nitride-forming elements include, in the order of their effectiveness: zirconium, titanium, magnesium, chromium, aluminum and manganese. Of these, zirconium is the most effective element for the spray casting method. If its effectiveness is taken as reference

~P

3 then the effectiveness coefficients of the other elements mentioned above are as follows: titanium magnesium 70%, chromium 40%, aluminum 30%, manganese By definition, the zirconium equivalent is the sum of the products of the nominal contents of the abovementioned nitride-forming elements and their effectiveness factors.

The recommended range within which the zirconium equivalent should be kept is 0.01 to 0.1% (cf. Fig. 2, which shows the influence of the Zr equivalent in the sprayed alloy on the change in reverse bending fatigue streng'h).

The method of this invention lends itself particularly well to improving the reverse bending fatigue strength of copper-base alloys of the following compositions in weight 1. copper-iron-zinc-phosphorus alloy of the following composition' 1.8 2.6% iron; 0.05 0.2% zinc; 0.015 0.15% phosphorus; remainder copper and normal impurities with the addition of one or more elements from the group comprising titanium, zirconium, magnesium, tin up to max. at least one of titanium, zirconium and magnesium being present in the alloy.

2. Copper-iron-phosphorus alloy of the following composition: 0.05 1.5% iron; 0.01 0.45% 25 phosphorus; remainder copper and normal impurities with the addition of one or more elements from the group comprising magnesium, titanium, zirconium, beryllium, tin up to max.

at least one of titanium, zirconium and magnesium being present in the alloy.

30 3. Copper-chromium alloy of the following composition: 0.3 1.2% chromium; remainder copper and normal impurities with the optional addition of one or more elements from the group comprising zirconium, titanium, iron, silicon up to max. 4. Copper-chromium-titanium-silicon alloy of the following composition: 0.1 0.5% chromium; 0.01 titanium; 0.01 0.25% silicon; remainder copper and normal 0 0 0 00 o 0 B 0 00 00000.

0 0 0 0 0 0 0 o o Oo *0* 0 0 0 0 0 O0 0 0 0 Q 0 0 o0 e, L I -1

I-

4 impurities with the optional addition of one or more elements from the group comprising zinc, iron, nickel up to max. 0.4%.

Copper-zirconium alloy of the following composition: 0.02 0.3% zirconium; remainder copper and normal impurities with the optional addition of one or more elements from the group comprising iron, chromium, tin, phosphorus up to max. 0.4%.

6. Copper-nickel-tin alloy of the following composition: 5.0 15.5% nickel; 2 8.5% tin; remainder copper and normal impurities with the addition of one or more elements from the groups comprising manganese, iron, zinc up to chromium, titanium, magnesium, zirconium up to phosphorus up to at least one of titanium, zirconium and magnesium being present in the alloy.

7. Copper-nickel-tin-titanium-chromium alloy of the following composition: 0.2 3.0% nickel; 0.2 tin; 0.1 1.5% titanium; 0.5 1% chromium; remainder copper and normal impurities with the optional addition of one or more elements from the group comprising iron, zinc up to 1%.

A 4 I 4 1114 U 4 44 8. Copper-nickel-tin-aluminum alloy of the following composition: 4 10% nickel; 1 3% tin; 1 3% aluminum; remainder'copper and normal impurities with the optional addition of one or more elements from the groups comprising manganese, iron, zinc, silicon up to 1%; zirconium, chromium, titanium up to magnesium and phosphorus up to 0.3%.

30 9. Copper-nickel-silicon alloy of the following composition: 1 4% nickel; 0.2 0.8% silicon; remainder copper and normal impurities with the addition of one or more elements from the groups comprising iron, manganese, zinc, tin up to chromium, titanium, 35 magnesium up to zirconium, phosphorus up to at least one of titanium, zirconium and magnesium being present in the alloy.

tIt d L (4l4 I- 5 Copper-tin-phosphorus alloy of the following composition: 1 11% tin; 0.01 0.35% phosphorus; remainder copper and normal impurities with the addition of one or more elements from the groups comprising zinc up to iron, manganese, nickel up to chromium, titanium, magnesium up to zirconium up to at least one of titanium, zirconium and magnesium being present in the alloy.

11. Copper-zinc alloy of the following composition: 2 51% zinc; remainder copper and normal impurities with the addition of one or more elements from the groups comprising lead up to 4% iron, tin up to 2%; nickel up to silicon up to 2%1 chromium, titanium, magnesium up to zirconium up to phosphorus up to at least one of titanium, zirconium and magnesium being present in the alloy.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in greater detail with reference to the following drawings wherein: Figure 1 is a graph of load cycles versus reverse bend fatigue strength for conventional wrought copper alloys.

Figure 2 is a graph of Zr equivalent versus nitride-forming effectiveness.

Figure 3 is a schematic view of spray casting apparatus useful in practising the method of the invention.

Figure 4 is a graph of load cycles versus reverse bending fatigue strength for alloy A cast in accordance with a prior art method and alloy B sprayed in accordance 30 with the method of the invention.

DETAILED DESCRIPTION An alloy A with 0.73% chromium, 0.08% zirconium, and remainder copper by weight) with normal impurities was cast in the form of billezs by the conventional continuous casting method and extruded at 900 0 C to form bars which were then reduced to 0.3 mm thick strips by rolling. By an appropriate annealing and forming sequence,

P

00 a 4 0O *1 4 (t C 4 C I a 2 00 the material was subsequently worked down to f inal thickness with a tensile strength of apprc~r. 590 N/mmn 2 a Vickers hardness of approx. 170 HV and an electrical conductivity of 48.1 m/0 mm 2 to O I5~ £0 0

S

Ga 6 An alloy B with 0.80% chromium, 0.09% zirconium, and remainder copper by weight) with normal impurities was spray cast to form a billet in accordance with Fig.

3.

On top of a spray casting chamber 1, a crucible 2 is placed and contains the melt 3. Through a stopper valve the melt 3 passes into a nozzle 4. In the nozzle 4, the atomizing gas 5 hits the melt 3 and atomizes the solid melt jet into a conical droplet jet 6. The droplet jet 6 hits a rotating base 7, which may be part of a formed billet, for example.

The formed billet, too, was extruded at 900°C to form a bar which was subsequently rolled to form a 0.3 mm thick strip by various cold forming steps and intermediate anneals, as used above for the continuously cast billets. The tensile strength achieved was 560 2 2 N/mm 2 with an electrical conductivity of 49.8 m/Qmm and a Vickers hardness of 150 HV.

Samples of 10 mm width were cut from the strip 20 specimens of both alloys and used to determine the reverse bending fatigue strength 5RB by means of a reverse bend test.

After 10 7 load cycles each, a reverse bending 0. fatigue strength of 8RB 190 N/mm 2 was measured for alloy A and a reverse bending fatigue strength of RB 220 N/mm for alloy B.

Fig. 4 shows the complete curves of the reverse bending fatigue strength 5 RB* It will be noted that the reverse bending fatigue strength of the specimens produced by the spray casting method is clearly superior to the reverse bending fatigue strength of the specimens produced by the continuous casting method.

Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or i -I I -7modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

T I tttr ti t i ,r a.

Claims

1. In a method of making a wrought copper-base alloy comprising melting the copper alloy and producing an initial form from which the final form is obtained by conventional hot and/or cold forming steps, the improvement for increasing the reverse bending fatigue strength of the copper-base alloy, comprising producing the initial form by a spray casting method using a copper-base alloy which contains nitride-forming elements selected from zirconium, titanium, magnesium, chromium, aluminum, manganese, boron, niobium (columbium), tantalum, vanadium, alone or in combination, in total concentrations ranging from 0.001 to by weight.

2. The improvement as claimed in claim 1, wherein a copper-base alloy is spray cast which includes nitride- forming elements in concentrations ranging from 0.001 to by weight.

3. The improvement as claimed in claim 2, wherein a copper-base alloy is spray cast which includes nitride- forming elements as zirconium equivalent in concentrations ranging from 0.01 to 0.1% by weight.

4. The improvement as claimed in any one of claims 1 to 3, wherein a copper-iron-zinc-phosphorus alloy of the i following compositi-ita in weight is spray cast: 1.8 2.6% iron; 0.05 0.2% zinc; 0.015 0.15% phosphorus; remainder copper and normal impurities with the addition of one or more elements from the group comprising titanium, zirconium, magnesium, tin up to max. at least one of titanium, zirconium and magnesium being present in the alloy.

5. The improvement as claimed in any one of claims 1 9 to 3, wherein a copper-iron-phosphorus alloy of the following composition in weight is spray cast: 0.05 iron; 0.01 0.45% phosphorus; remainder copper and normal impurities with. the addition of one or more elements from the group comprising magnesium, titanium, zirconium, beryllium, tin up to max. at least one of titanium, zirconium, and magnesium being present in the alloy.

6. The improvement as claimed in any one of claims 1 to 3, wherein a copper-chromium alloy of the following composition in weight is spray cast: 0.3 1.2% chromium; remainder copper and normal impurities with the optional addition of one or more elements from the group comprising zirconium, titanium, iron, silicon up to max.

7. The improvement as claimed in any one of claims 1 to 3, wherein a copper-chromium-titanium-silicon alloy of the following composition in weight is spray cast: 0.1 chromium; 0.01 0.5% titanium; 0.01 0.25% silicon; remainder copper and normal impurities with the optional gas addition of one or more elements from the group comprising Srt zinc, iron, nickel up to max. 0.4%.

8. The improvement as claimed in any one of claims 1 to 3, wherein a copper-zirconium alloy of the following composition in weight is spray cast: 0.02 0.3% zirconium; remainder copper and normal impurities with the optional addition of one or more elements from the group comprising iron, chromium, tin, phosphorus up to max. 0.4%. 1.

9. The improvement as claimed in any one of claims 1 to 3, wherein a copper-nickel-tin alloy of the following composition in weight is spray cast: 5.0 15.5% nickel; 2 8.5% tin; remainder copper and normal impurities with the addition of one or more elements fr)m the groups comprising manganese, iron, zinc up to chromium, S l *titanium, magnesium, zirconium up to phosphorus up to at least one of titanium, zirconium and magnesium being present in the alloy.

The improvement as claimed in any one of claims 1 to 3, wherein a copper-nickel-tin-titanium-chromium alloy of the following composition in weight is spray cast: 0.2 3.0% nickel; 0.2 3.0% tin; 0.1 1.5% titanium; 0.5 1% chromium; remainder copper and normal impurities with the optional addition of one or more elements from the group comprising iron, zinc up to 1%.

11. The improvement as claimed in any one of claims 1 to 3, wherein a copper-nickel-tin-aluminum alloy of the following composition in weight is spray cast: 4 nickel; 1 3% tin; 1 3% aluminum; remainder copper and normal impurities with the optional addition of one or more elements from the groups comprising manganese, iron, zinc, silicon up to zirconium, chromium, titanium up to magnesium and phosphorus up to 0.3%. o*

12. The improvement as claimed in any one of claims 1 to 3, wherein a copper-nickel-silicon alloy of the m. following composition in weight is spray cast: 1 4% nickel; 0.2 0.8% silicon; remainder copper and normal impurities with the addition of one or more elements from *o the groups comprising iron, manganese, zinc, tin up to chromium, titanium, magnesium up to zirconium, phosphorus up to at least one of titanium, zirconium and magnesium being present in the alloy. o a o

13. The improvement as claimed in any one of claims 1 to 3, wherein a copper-tin-phosphorus alloy of the following composition in weight is spray cast: 1 11% tin; 0.01 0.35% phosphorus; remainder copper and normal Simpurities with the addition of one or more elements from the groups comprising zinc up to iro., manganese, *4 0o nickel up to chromium, titanium, magnesium up to Li L.r t S- 11 zirconium up to at least one of titanium, zirconium and magnesium being present in the alloy.

14. The improvement as claimed in any one of claims 1 to 3, wherein a copper-zinc alloy of the following composition in weight is spray cast: 2 51% zinc; remainder copper and normal impurities with the addition of one or more elements from the groups comprising lead up to 4% iron, tin up to nickel up to silicon up to 2%; chromium, titanium, magnesium up to zirconium up to phosphorus up to at least one of titanium, zirconium and magnesium being present in the alloy. DATED this 25th day of July 1995. WIELAND-WERKE AG By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent Attorney' of Australia i t I {i 44; t A i t I METHOD OF IMPROVING THE REVERSE BENDING FATIGUE STRENGTH OF COPPER-BASE ALLOYS ABSTRACT OF THE DISCLOSURE Ott The reverse bending fatigue strength of a wrought s r0 o. copper-base alloy is improved compared with conventionally produced wrought alloys of similar composition by producing the initial hot and/or cold :.oD workable body by the spray casting method using a copper-base alloy which contains nitride-forming elements (such as zirconium, titanium, magnesium, chromium, aluminum, manganese, boron, niobium, tantalum, vanadium) alone or in combination, in the total concentration range from 0.001 to 3.0% by weight. The initial body then can be processed by conventional hot and/or cold working operations to a final form. o K'