DE2040870B2 - CONTINUOUS WIRE RESISTANCE ANNEALING PROCESS - Google Patents

Description

The invention relates to a continuous wire stand that can be eliminated. Because the wire is made by Strorn resistance annealing process -Only coarsening the grain impulses is heated, some places are twice structure, b / v. a continuous wire resistance annealed, which however does not cause any damage annealing process, in which the wire is being used, because with such a rapid glow there is no name ^ - whose electrical resistance occurs with the help of worthy grain growth. The properties of the electric current at the recrystallization temperature of 35 annealed wire correspond on average is brought to obtain a coarser grain size. the properties of wire based on conventional In practice, a whole range of wire types and ways of resistance are known. the Annealing process, which in principle is divided into two groups of grain size, is also divided into two groups during resistance annealing let: by trying to coarsen, that one starts with the

1. Churgcn annealing processes, in which the wire temperature increases relatively quickly and another is wound in bundles or on coils in furnaces. B bell stoves. Salt cooling flow.gkew prevented. Although the wire several bath stoves. Roller hearth furnace. Muffle furnace ti. Like checks durch.auft. around here the conditions for being glowing. The heat transfer happens ^{to create a} Kormvachsturr, but is because of it by radiation and / or convection. ⁴⁵ great inertia of grain growth either cmc ",. , an inexpediently long annealing section is required, or

7. Continuous annealing processes in which the _{dcr crna} | _tene advantage remains very small.

Wire by an overall of externally heated tube _{following the} conventional Widerstandsglühverführt or drive directly or inductively resistively heated is ν rwicgend annealed copper, and for this ^{vv 'r} "-. 50 material, the process is also good because the check

The long annealing time is characteristic of the batch annealing process, which is softened even at relatively low temperatures. in order to enter the compact wire coils and to bring the grain size easily / u to a uniform temperature in general. Furthermore, because the long annealing time in these processes can prevent the grain growth, alloy constituents and impurities are absent, and the high temperatures in these furnaces lead to an increase in this (sticking ) of the Drathwindungen Icaht up the desired properties ^Vl 'CHT to occur. Furthermore, the cleanliness of the can may, however, a microstructure having coarse crystals m, which at the wire after annealing process, caused for. example, by the known processes only by a grain Changes in the furnace atmosphere, which can be achieved through growth, can easily result in a non-uniform vaporization of the drawing fat adhering to the wire or a moderate structure, which does not cause property fluctuations in the wire components, such as zinc, to be perfect. In general, it is wire However, on the other hand, with the known resistance annealing processes, these processes can be achieved at all thanks to the long Annealing time and the impossible to produce coarse grain sizes,
According to the invention, the coarsening of the grain structure properties of the material within the structure with a continuous wire resistance of wide limits can be regulated relatively effortlessly. The annealing process is achieved in that the annealing process is carried out in two.

<Jie among others van der ZieligescUwindigkeil, the used protective gas, the cooling, the wire thickness, the Cilühstrecklänge and the Scilidustemperalur des Pnilues is co-determined, a controllable amount Germs are generated, whereupon in the second stage 5 at a higher temperature the actual annealing is carried out in such a way that the wire is finished di.-ser Ciliihsiufe is completely recrystallized.

In the case of resistance annealing, the metal is softened by recrystallization. In the region There are three areas of crystallization: recovery, primary revision, and grain growth. The primary Recrystallization happens in such a way that germs grow in the form deformed structures, which then grow into finished grains or crystals. 15th

H, Mm Grain growth grows in part at the primary recrystallization, crystals formed on top of the other crystals. The properties of the »■ eic! 'En wire are dependent on the grain size. With increasing grain size, strength and decrease Stop as the toughness increases. The grains-IV is regulated by the annealing temperature so that the desired properties are obtained. At the Resistance annealing comes because of the short annealing time Vaum a notable crystal growth. The Dk grain size of the resistance-annealed wire remains essentially at the same level as in primary recrystallization is achieved. d. that is, the number of crystals is the same as that of the resulting crystals Crystal seeds.

The rate of nucleation is never staik from that T'-temperature dependent. The number of germs increases with increasing temperature. Therefore applies to the resistance annealing the following: The higher the temper If only during nucleation, the smaller the grain size remains. With the conventional will to resist nucleation occurs at a very high temperature d; the temperature because of the short Gluhzcit ' is increased very quickly, so that the wire worked in this way generally has a low kornerolic having. If a coarser grain size is desired, the nucleation should be at low temperature happen.

The present invention advantageously solves this problem so that the annealing is carried out in two stages. In the first annealing stage, a suitable number of crystal nuclei is formed, and to be achieved by adjusting the temperature so that the available zen. a precisely desired amount of germs is produced. In the second stage then "the growth of the nuclei formed takes place until complete recrystallization has taken place. This second stage has to take place at a higher temperature than the first stage because of the short time it takes to complete it only an insufficient number of nuclei in the first annealing stage, so it follows that in the deformed structure in the second stage many new nuclei arise, which result in an uneven grain structure, and the wire does not acquire the desired properties first stage, however, * u much nuclei gebjdet, this gives a small grain size, bringing the benefits of Keimbildungsglüheiw be lost. In practice gesSt dieslr annealing process using _6s three or four contact roller !! and one or more ^St D £ ^q Fiction? fertil will be described in detail below with reference to the drawings, in which two embodiments, intended only as examples, are shown described.

F i g. 1 shows the system for a two-stage annealing process, in which the wire is between the first and second stages, i.e. Ii, between nucleation and Growth phase is not cooled;

F i g. Figure 2 shows the system for a two-stage annealing process in which the wire is between nucleation and Growth phase is cooled.

In Fig. 1 the wire runs over the contact rollers 1 and 2, where the preheating takes place. In this common preheating stage, with so Worked at low temperatures so that the wire does not oxidize and in no case the recrystallization nuclei form. This preheating only serves as an auxiliary stage, which can also be dispensed with. The nucleation annealing according to the invention occurs between the contact rollers 2 and 3, in which the Current is chosen so that at the end of this annealing stage exactly the right amount of crystal nuclei in the wire is available. This annealing stage is immediately followed, without the wire being cooled in the meantime becomes, between the contact rollers 3 and 5 the growth rabbit at. in which the complete crystals form. The structure is after this second annealing stage completely recrystallized. On the contact roller 5, the wire is cooled so far that the wire is no longer oxidized. The cooling is usually done according to the conventional method using water. Water emulsion or the like, the contact roller 5 being in the coolant and the wire running through it. To avoid oxidation, the distances between the contact rollers 2 and 3 and 3 bi., 5 generally provided with a protective gas jacket. On the route between the contact rollers 5 and 6 is the wire of a light dry heat subjected, which is carried out at such low temperatures that no oxidation happens on the wire and in no case grain growth can occur.

That in F ^; i g. The system shown in FIG. 2 differs from the system in FIG. 1 in that after the nucleation phase (between the contact rollers and 3), the contact roller 3 is also cooled in the same way as on the contact roller of the example described above. Between the contact rollers 3 and 4, as on the path of the contact rollers 1 and 2, the wire is preheated, but this can also be dispensed with if necessary. This arrangement ensures that the contact roller 3 is damaged neither by oxidation nor by contamination, as is the case with the one shown in FIG. I shown the system can easily be the case. The subsequent annealing takes place in the manner shown in FIG. illustrated way.

With the method according to the invention, fabric wires (Fourdrinier wires) were annealed with success. When glowing tissue shot diets (80 ° / ₀ Cu, 20% Zn), a wire diameter of 0.23 mm and a pulling speed of 8.8 m / s were carried out according to the conventional process, ie with a one-step process for the O , 2-Grem: e achieved a minimum value of 16.5 kp / mm ⁴ and a maximum value of about 0.008 mm for the grain size. With the two-stage process according to the invention, under the same conditions, the value for the 0.2 limit was 12.8 kp / mm ² and for the grain size the value was 0.025 mm

achieved. In the one-step process, the length of the annealing section was around 800 mm, and in the two-step process, the nucleation section was around 1400 mm long. The temperature at the end of the first annealing about 400 to 500 ⁰ C, at the end of the second stage is about 850 to 95O ⁰ C.

In simulation tests, two current pulses of suitable strength and duration were fed into the wire, and the wire was cooled in between. The length of the wire in the device used was about 250 mm, the duration of the current pulses was 50 to 300 ms, and a hydrogen gas stream served as the coolant. For pure nickel wire (diameter 0.17 mm) a 0.2-limit value of 15.9 kgf / mm gave ^a at a temperature of about 300 ^C C in the first stage and about 1000 ° C in the second stage. If the temperature in the first stage (nucleation) remained lower or rose higher than the stated value, values of 18.1 to 19.0 kp / mm * were achieved with the same main annealing stage for the 0.2 limit. In tests with pure copper wire (diameter 0.15 mm), after suitable preheating (approx. 25OX), the value 6.9 kp / mm ^{2 was} obtained for the 0.2 limit, while otherwise it was about 7.5 kp / mm ² lay. In the second annealing step of the experiments with copper wire, the temperature was increased to about 95O ⁰ C. The effect is relatively small with Cu wire, as is to be expected based on the explanations given.

The specified temperatures are only to be regarded as guidelines, because they are from a large Number of factors influenced, such as B. the drawing speed, the protective gas, the cooling, the Wire thickness, the length of the annealing section, the solidus temperature, etc.

The inventive method can also be used in Apply in connection with inductive heating, but this is with the current state of the art should not yet come into question, since inductive heating is only used when it is unnatural Working speeds or low temperatures.

1 sheet of drawings

15 t;

Claims (3)

1 2 running speed of the wire is low, and this makes these processes expensive. If the capacity claims: by lengthening the furnace or by increasing the number of the furnace at the same time 1. Continuous wire resistance annealing 5 wires increased, so this only leads to one drive to coarsen the grain structure, d a - very cumbersome and complicated furnace construction g e k e η η ζ e i c h n, e t that the glow tion. With the inductive method, the capacity remains is carried out in two stages, the first being extremely low, so this procedure for wire im Level at an empiriHi certain lower general only seldom and for thin wire over-temperature, which, among other things, is out of the question for the Ziehio. As for the continuous speed, the protective gas used, the process, so one is increasingly Cooling, the wire thickness, the length of the annealing to the resistance annealing process (resistive annealing path and the soliduotemperature of the wire) passed over, as it depends on very high levels, a controllable amount of germs speeds up and, compared with the rest of the incandescent material, it is incandescent is, whereupon in the second stage at 15 ovens, due to the small dimensions of the required higher Temperature characterizes the actual annealing so borrowed annealing device. In particular made becomes that the wire after completion one applies this procedure to-.ammen with today the phase v> »is constantly recrystallized. Wire drawing machines, whereby the 2. The method according to claim 1, characterized marked hardened wire drawn directly into the annealing device that the wire between the first and 20 is conducted. The disadvantage of the resistance annealing process is that the second stage is cooled. rens, however, it must be stated that it is through the 3. Application of the method according to claim 1 extremely fast, instead of in fractions of a second Annealing of wire on copper or a finding annealing, often does not succeed in the wire Copper alloy. to give desired properties. 25 In the German patent specification 1 186 223 is a Resistance annealing process described in which the The wire is annealed by means of current pulses: this should remove the irregularities of the wire, the z. B. em-