DE2436983B2 - PROCESS FOR DETERMINING HARDNESS AND CONVERSION BEHAVIOR AS WELL AS GRAIN-SIZED METALLIC MATERIALS - Google Patents

Description

The invention relates to a method for determining the hardenability and conversion behavior and the Grain size of metallic materials.

To determine the analysis of molten metal it is z. B. from DT-AS 20 35 420 known by means of a small mold to take samples from the molten metal in the ladle and after Cooling of the poured sample z. B. determine the composition of the material by means of spark analysis.

For the production of tensile test specimens for determination mechanical parameters such as tensile strength, 0.2 limit, elongation, constriction and modulus of elasticity, by means of notched impact specimens, insert, step hardness, core hardness, Brugger and Jominy specimens, one is from a z. B. 25 kg cast ingot assumed the z. B. was thermoformed by forging or rolling and then made by machining the sample was produced in the desired dimensions.

One reason for this relatively cumbersome, material and costly production Such samples consisted in the fact that for the test a sample with a homogeneous structure over their entire Length and across its cross-section was required. By casting, samples with such were homogeneous Vessels have not yet been able to be produced because the relatively thin and long samples at Casting the same voids formed. According to the »Foundry Lexicon«, it was 1972, pages 340 and 526, although known to either cast test rods onto the casting or to separate them to water. To do this, however, it was necessary to secure a tight feed, i.e. by pouring or letting it flow again to obtain dense, pore-free and void-free samples. When taking the ingot casting, the However, the sample is so fast that such replenishment cannot take place, so that voids are formed

Another reason why it was believed that the tests were only carried out on plastically deformed specimens to be able to, consisted in the desire to participate in the rehearsal

blackboard

Comparison of the conversion behavior with those of the sampling process

45 to produce the state as precisely as possible - in which this can be achieved from the material through hot deformation manufactured workpiece is located. In this way, workpiece parameters were determined. the The comparability of such workpiece parameters depends heavily on the extent to which the sample is actually in deformed the way later the workpiece made from the material.

As I said, the production of such samples requires a relatively large amount of material and processing, because the samples were made from one larger block worked out by reshaping. The deformation of the block doesn't just mean In terms of production technology, it also entails additional expenditure, but also delays the production of the sample.

The object of the present invention is, in addition to simplifying and making the production of samples cheaper Above all, the creation of a sample on which the material parameters can be determined, which are a general Statement about the hardenability and conversion ratio as well as grain sizes of a metallic material, regardless of the type and scope of its plastic deformation.

To solve this problem, it is proposed according to the invention that the test be carried out on by means of a mold drawn from the pouring stream, only brought into the desired shape by machining to make samples that are not plastically deformed. According to the invention by means of a mold from the Sample blocks taken from the pouring stream can then be heat-treated in the usual way.

Surprisingly, it has been shown that one does not necessarily need plastically deformed samples as before must use, but that according to the invention with plastically not deformed cast samples material parameters can be determined, which makes a general statement about the hardenability and transformation behavior as well as the grain size of metallic materials, regardless of the deformation.

Using the example of a forehead quenching hardness test (Jominy test), this is illustrated in the diagram, Figure 1, illustrates from which the almost identical course of the heir curves of a produced in the manner according to the invention Sample (dashed line) and a sample produced from a 25 kg block in a known manner by hot forming (solid line) can be found.

From Figure 2 it follows that the grain number according to A.S.T.M. measured on the sample prepared according to the invention both for the sample prepared in the previously known manner from the 25 kg block and for the Bloom and the final product determined. It follows that the inventively produced Sample is suitable for determining the grain size of the plastically deformed end product.

of the material ZF 1 (F) according to different

Heat treatment: 30min 880 ° C / L + 60 min 9CK) ⁰ C + switching to 660 ° C

1.5 h 660 ° C / W ferrite pearlite

2 hours 660 "C / W
Ferrite pearlite

Cast sample 35 mm 0 as cast
25 kg block forged to 35 mm 0, bloom 250 rnm 0 forged to 35 mm 0

65% 65% 60% 35% 35% 40%

60% 60% 60%

40% 40% 40%

fr-

The table shows the transformation behavior using the example of steel ZF 1 (F). Here too the result Comparison between the sample produced according to the invention, referred to as the "cast sample", and one from the 25 kg block and one made from the bloom Sample that the conversion behavior, as it was determined with the aid of the cast sample produced in the manner according to the invention, just as well and exactly determined can be, such as on one from a 25 kg block or the sample taken from the bloom in a previously known manner.

When carrying out the method according to the invention, casting specimens with smaller dimensions can be used than before, where one had to start with blocks weighing more than 20 kg when preparing samples. This reduces the cost of materials on the one hand. Furthermore, the previously common hot deformation is used of the ingot is dispensed with according to the invention, so that the production of samples is further cheaper and also accelerated. It thus proves to be technical more advanced than previously known processes.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Method for determining the hardenability and transformation behavior and the grain size of metallic Materials that they have in their final state produced by plastic deformation, d a by characterized in that the test is carried out on plastically not deformed, only by machining into the desired shape samples are taken.