DE1955449C - Copper iron aluminum alloys - Google Patents

Description

A well-known proposal (USA.-PatentschKft 3 384 517) relates to copper-iron-aluminum alloys. which contain 35 to 75 percent by weight copper, 20 to 50 "η iron and 15 to 5% aluminum. It These alloys are a copper-rich mixed crystal, containing 5 to 10 "Ό aluminum, and an iron-rich mixed crystal containing 10 to 20% aluminum, the latter as disperse phase is present and can be brought into a fibrous form by hot forming, ι ο

The reason for the good mechanical properties of such materials is that the copper-rich mixed crystal as a continuous phase the iron-rich mixed crystal as a disperse phase contains, after reshaping in fibrous form. which acts as a reinforcement of the basic mass. In spite of the good mechanical properties of such materials still leave their corrosion resistance to be desired.

It is therefore unlikely that, because of their extensive oxidation, these base alloys can even be used under normal atmospheric conditions or even in the navy.

The invention now brings similar alloys, but with improved corrosion resistance exhibit.

However, corrosion resistance is of particular importance. The corrosion resistance certain materials depends largely on the environmental conditions in the context of the application away. The material can be used in conventional tests to determine the corrosion resistance, namely by dipping in a 3% saline solution, give good results. This gives you certain Clues about the usability of the material in the Navy. Such examinations can show that the material in question is satisfactory in that it does not become stained or superficial corrodes, in other words, that it corrodes under normal environmental conditions without discoloration is constant. However, this does not mean that such a material is used shows no signs of corrosion on the surface at sea. Other materials can despite the fact that they do not correspond to the extreme stresses encountered in shipping, in more corrosive ways Atmosphere at higher temperatures can be very satisfactory when it comes to good scale resistance and a change in the color of the material is of no major importance. There are the various types and levels of corrosion resistance; as can be seen from the description is, according to the invention, it is about alloys of the basic composition in the sense of older proposal, which are particularly resistant to corrosion in at least one respect.

According to the invention, the base alloy consists of 35 to 75% Cu, 20 to 50% Fe and 15 to 5% Al, which consists of a copper-rich mixed crystal with 5 to 10% Al and embedded therein a disperse phase in the form of an iron-rich mixed crystal with 5 to 20, preferably 5 to 10% Al, further alloying elements are added in order to make the iron-rich, solid solution more noble and / or to produce an adhesive protective film on this iron-rich phase. These additional alloying elements are nickel, chromium, tungsten, molybdenum and cobalt as a group and titanium. Niobium. Tantalum. Zirconium and silicon as the other group. The percentage by weight of these additional alloying elements is h, s about 15%. The first group leads to more noble properties of the alloy, whereas the second group, ·, · _{favors the formation of a protective layer on the VV 1} K-stolT. In some cases, one or more alloy elements can be used. which serve as additives according to the invention, also more than one function

fulfill. ·,

The limit values considered above are unu-r Consideration "of usual analysis teachers and Understand production fluctuations.

It has been shown that when used alone \>. R, Chromium e "s to a concentration in the iron kingdom Phase comes, whereas with the sole use of nickel this to a lesser extent in üi-r Copper phase is enriched. If <k When alloying elements are used, there is an advantageous influence in both phases. The soluble The ability of both alloying elements in the iron-rich phase is somewhat increased. However, it cannot do everything in it the cause of the improvement in properties can be seen.

Preference is given to alloys according to the invention with considerable proportions of additives, namely flour greater than about 15% per alloy element. The alloy contains nickel and / or chromium. so should the nickel content is preferably between 3 and 12% and the chromium content between 3 and 9%. Alloys with five components, namely 47.4% copper, 30.7% iron, are particularly suitable. 7% aluminum. 7.4% nickel and 7.5% chromium. In this alloy the aluminum is essentially evenly distributed between the iron-rich and copper-rich phases. Corrosion tests with these Alloys have shown that the corrosion resistance is markedly improved. even when applied in the context of shipping.

According to a particular embodiment of the alloys according to the invention, these have a matrix from a copper-rich mixed crystal, containing 5 to 10% aluminum, in which an iron-rich, disperse mixed crystal containing about 5 to 10%. but possibly up to 20% aluminum, is present. According to the invention, these alloys contain both nickel and chromium.

In the case of the alloys, the older proposal gave particular importance to the fibrous shape is to be assigned to the iron-rich phase, in the present invention the meaning is not so much that. The alloys according to the invention do not necessarily have to have the disperse phase in the form of have fibrous deposits. In the above-mentioned five-component alloys, found that the corrosion resistance is remarkable in the state immediately after casting as well as after mechanical deformation.

To improve the properties of the copper-iron-aluminum alloys according to the invention To show, the results of tests with comparable alloys are given below. Table 1 shows the compositions of the alloys tested, with alloy A being the base alloy and the alloys B, F, G, H, I and K contain nickel and chromium. These alloys Hilden a group because in this 5-component system the nickel content is varied, whereas the aluminum and chromium content is essentially

i 955 449

remains constant. Alloy D contains nickel and chromium in essentially equal, comparative terms but smaller proportions, whereas alloy M has a particularly low aluminum content having. Alloy L also contains carbon, while alloys C, E and J contain as corrosion inhibitors Addition either only nickel or only chromium.

table

.euation Cu Fc ΛI Cr Ni C. Λ 61.0 27.5 11.5 F. 50.47 33.2 7.0 7.47 1.86 G 49.96 32.78 7.0 7.47 2.79 H 49.44 32.37 7.0 7.47 3.72 B. 47.38 30.71 7.0 7.47 7.44 I. 43.30 27.06 6.89 7.91 15.02 K 48.63 22.03 7.06 5.98 16.24 M. 46.20 29.75 5.0 7.65 Π.4 D. 49.70 36.3 7.0 3.74 3.26 L. 47.38 32.33 7.0 5.81 7.44 0.04 C. 51.34 34.61 7.5 6.37 E. 51.5 34.03 7.0 7.47 J 51.4 36.15 7.27 5.02

Comparative tests were carried out in the laboratory on the corrosion resistance of the alloys in the as-cast state, specifically in a stationary 3% sodium chloride solution. The following table shows the weight loss in g / dm ² .

Table 2

Days 7th Λ F. G H B. 0 I. 0 until 14th 1.11 1.00 2.58 0.24 0 until 28 1.01 0.79 1.63 0.33 " 0 until 52 3.99 0.96 0.86 1.08 0.25 0 until 56 4.34 0 0 until 70 1.01 0.77 0.77 0 until 91 0.06 0.22 0 until 99 0.97 0.69 0.63 0 until 114 0.24 0 until 127 3.93 0.94 0.63 0.64 0 until 141 0.09 0.27 0 until 155 0.91 0.61 0.57 0 until 169 0.30 0 until 186 0.83 0.59 0.50 0 until 206 0.78 0.52 0.47 0.31 0 until 239 3.72 0.19 0 until 365 0.28 0 until

K 0 M. D. L. C. E. J 0.15 0 1.79 5.27 1.56 2.66 0.20 0 2.92 0.01 5.32 1.33 3.24 0 3.50 4.98 1.39 3.51 0.34 0.23 0 3.71 1.44 4.25 3.92 0.21 3.16 1.42 0.28 4.14 4.05 0.21 2.88 1.42 0.34 406 4.06 0.25 2.73 1.43 0.38 4.22 1.41 4.10 0.24 2.55 2.43 4.09 1.37 4.05 0.35

0 to 7
Obis 14
0 to 28
Obis 52
0 to 56
0 to 70
0 to 91
Obis 99
Obis 114
Obis 127
Obis 141
0 to 155
0 to 169
0 to 186
0 to 206
0 to 239
0 to 365

If one compares the data of alloys A and B, it can be seen that the influence of the nickel and Chromium content on the ternary alloy is considerable.

If alloy B is hot rolled, it only shows up after a corrosion test over 42 days few rust spots, and after 3 months immersion it was found that alloy B was cast and when hot-rolled was still much less corroded than alloy A and also all other ternary copper-iron-aluminum alloys exceeded in these investigations.

Alloy B remained both in the as-cast state and hot-rolled when used internally, at least Bare for 6 months and can therefore be used as a substitute for brass for decorative purposes can be used, which is already matt under normal environmental conditions.

The color of the alloys is between steel gray and champagne. The alloys according to the invention In terms of their magnetic properties, they can be between non-magnetic and ferromagnetic lie.

From Table 2 it can be seen that alloys F, G, H. I and K are not quite as durable, possibly because the compositions are not exactly comparable. It is found that the corrosion resistance this group of alloys increases with the proportion of nickel. Through this at least one rule of thumb for selection for special purposes is obtained. The investigations of alloy M were continued, but this alloy is evidently particularly corrosion-resistant.

Alloy D may show little because of its low chromium and / or nickel content improved properties compared to other alloys containing nickel and chromium.

Alloy L with its carbon content is heat-age hardenable after deformation, s-? that one can set the desired hardness. The corrosion resistance is good; although the alloy is at did not prove so very well to these very rough test conditions, but it turned out to be sufficient

is resistant to tarnishing or surface discoloration. Alloy J is no better than alloy A. In the tests with the saline solution, however, is exceptionally good in terms of superficial discoloration or starting. It is very suitable for making cutlery and seems to be a good substitute for corrosion-resistant steel. For this reason one can also use these and other alloys apply according to the invention in construction.

Some of the alloys of the present invention can be easily hot rolled, some cold rolled, and some roll both cold and warm. In some deformed alloys, the iron-rich will disperse Phase probably present fibrous, whereby the mechanical properties of the Alloys are improved.

Test bars made of alloy B in the as-cast state have a breaking strength of about 83.5 kg / mm ² , at 0.1% limit 44 kg / mm ² with an elongation of 17%. In cold rolling with a cross-section reduction of about 18% and seven intermediate anneals at 970 ° C., the tensile strength is 105 kg / mm ² and the yield strength is 37 kg / mm ² .

Claims (4)

Patent claims: 1. Copper-iron-aluminum alloy made from 35 to 75% Cu, 20 to 50% Fe and 15 to 5% Al, from a base of copper-rich mixed crystal, containing 5 to 10% aluminum, and a disperse phase in the form of an iron oak Mixed crystal containing 5 to 20%, preferably 5 to 10% aluminum, characterized by at least one additional alloy element in the form of nickel, chromium, tungsten, Molybdenum, cobalt, titanium, niobium, tantalum, zirconium and / or silicon in the corrosion resistance improving amounts up to 15% each. 2. copper-iron-aluminum alloy according to claim I, characterized in that the proportion of nickel is 3 to 12%. 3. copper-iron-aluminum alloy according to claim 1 or 2, characterized in that the proportion of chromium is 3 to 9%. 4. copper-iron-aluminum alloy according to claim 1 to 3, characterized by a content 47.38% copper, 30.71% iron, 7% aluminum, 7.47% chromium and 7.44% nickel.