DE707940C - Process for the production of objects with a smooth surface with coarse grain formation from magnetic steel sheets or strips - Google Patents

Description

Process for the production of objects with a smooth surface with coarse grain formation 9 from magnetic steel sheets or strips Ee # is known that in objects made of soft iron, which are magnetically soft and have good electrical properties, such as magnetic yokes, above all a low one Must have remanence and low coercive force and which should under certain circumstances have a low watt loss, the coarsening of the cortex plays a decisive role. For this purpose, the iron can also contain alloy components, for example silicon, which improve the electrical properties. The coarsening of the grain can be achieved in a manner known per se by appropriate cold forming and by appropriately adapted annealing temperatures. But if a so it treats iron or steel sheet or strip with coarsened grain of a further cold processing z. B. subjected by bending or deep drawing, then the disadvantage turns out that the surface is very rough and cracked. This property is particularly unpleasant when a smooth surface is important, for example for nickel plating or painting.

According to the invention, it is possible to achieve a smooth, clean surface with coarsened grain in the ZD finished product and thus the precondition for favorable magnetic and electrical properties in that, after the cold deformation which determines the cross-section of the material, the degree of which depends on the grain coarsening to be achieved later can be made, first an annealing is connected, which is selected depending on the composition of the material so low that, if a grain coarsening is avoided, the elongation is increased and the strength is reduced so that further cold processing is possible without impairing the surface texture. If the finished product is then annealed by cold processing, including punching, which is known to be associated with a strengthening of the parts adjacent to the cut edges, at temperatures that trigger recrystallization, then a finished product is obtained that is cleaner , smooth surface a grain that is coarser than the initial state. having. Further details can be found in the example below.

F-in steel with 0.0501, C, 0.03 '/, -% 1 "and an Si content of 0.51 /, was first subjected to the usual cold working and annealing treatment Annealed at 58o11 C. Fig. i shows the fine-grained structure of this state, which is sufficiently fine-grained for further processing. The finished part was then made from the material and then annealed in the finished state at 80 ° C. The material treated in this way had the extremely coarse shown in Fig. 2 Grain, which has the well-known good effects on the electrical and magnetic properties, but the surface of the finished parts is still completely smooth.

The degree of cold deformation mentioned in the previous example and the specified annealing temperatures naturally change in their order of magnitude something in the presence of other materials. But you can go through some easily preliminary tests to be carried out are determined.

Claims (1)

PATENT CLAIM: Process for the production of objects with a smooth surface with coarse grain formation, which are magnetically soft and have good electrical properties, e.g. B. low remanence and low coercive force, must have, made of soft, optionally alloyed iron or steel sheets or strips, characterized by the measures to be taken in the following order: a) The sheets or strips are in a known manner by cold forming to the desired Brought final thickness, b) then annealed at a temperature below the recrystallization temperature, for example 5 ° C. existing cold processing brought to the form required for the use of the objects, the sum of this cold processing and the previous cold deformation according to a) representing a critical cold deformation, and d) finally subjected to the recrystallizing final annealing in a known manner.