JP3335770B2 - Evaluation method of scale peelability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accurately and efficiently evaluating the scale peelability or adhesion of a steel material, especially a steel material having a small amount of scale.

[0002]

2. Description of the Related Art A scale of steel material is a serious problem because it peels off at the time of cold working and is scattered as dust, thereby significantly deteriorating the working environment. Therefore, recently, there is an increasing need for a scale measurement method as a countermeasure.

[0003] In cold working, the degree of working (working strain) varies greatly depending on the object, and it is necessary to quantitatively grasp the scale peelability under each condition. Conventionally, as a method for evaluating scale releasability, there has been the following method for measuring the mechanical releasability (hereinafter, referred to as mekades characteristics) of a scale performed on a wire or the like.

[0004] First, the material is cut to the same length as the tensile test specimen, the tensile tester gives the same elongation as the bending roller of the mechanical descaler, the scale is peeled off, and the weight loss of the test specimen is reduced. Wanted the mechanical death characteristics of

[0005]

However, in the above-mentioned method, since a small weight change due to scale peeling is measured with a large test piece, a reading error at the time of weight measurement is large. Steel was developed, and its measurement error became an increasingly big problem.

Further, in this method, since the weight of the test piece is measured as described above, the test piece may be scraped by, for example, chuck indentation at the time of imparting tensile strain, which also increases the measurement error and further increases the predetermined error. This makes it difficult to accurately measure the amount of scale peeling during distortion.

[0007] The present invention solves the above-mentioned problems, and provides a method for accurately and efficiently evaluating scale peelability even for a steel material having a small amount of scale generation.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a test piece taped at both ends and used as a material to be evaluated is subjected to a load by a tensile tester until a constant strain is reached, and the test is carried out until the constant strain is reached. This is a method for evaluating scale releasability, in which a scale peeled and dropped from a piece is adsorbed by a magnet, the weight of the adsorbed scale is weighed, and the scale releasability of the steel material is evaluated based on the weighed value.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention and the operation thereof will be described below in detail with reference to the drawings.

FIG. 1 is a schematic side view showing one embodiment of the present invention. First, a test piece 1 having a fixed area as a surface to be evaluated 2 left in the center and taping 3 with vinyl tape at both ends. Is attached to a tensile tester 4 and a test piece 1
The extensometer 5 for measuring the amount of strain of is set.

A magnet 6 is fixed by a fixing jig 7 at opposite positions on both sides of the surface 2 to be evaluated of the test piece 1. In this state, the test piece 1 is pulled by a tensile tester 4 to give a certain strain. The strain is held at that time, the scale amount peeled off from the test piece 1 and adhered to the magnet 6 is weighed by that time, and the scale peelability is similarly evaluated by the weighed value under the next strain condition. Is the way.

Here, the magnet 6 for recovering the scale that has peeled off from the test piece 1 is fixed with the upper end separated from the test piece 1 and the lower end close to the test piece 1. The reason is that if the upper end of the magnet 6 is too close to the test piece 1, the scale falling from the test piece 1 extending upward will ride on the cover of the magnet 6, and if it is too far away from it. This is because the magnetic force of the magnet 6 is weakened and the scale recovery rate is reduced.

On the other hand, the lower end is set so as not to be in contact with the test piece 1 because the recovery rate of the scale is the best. The distance between the upper and lower ends of the magnet and the test piece 1 may be determined at any time according to the strength of the magnetic force of the magnet.

A point to be noted when fixing the magnet 6 is that the steel material as the test piece 1 is stretched during the test.
That is, it is set so as to cover the elongated exposed surface of the steel material. If the magnet is wound with paper, for example, the scale attached to the magnet can be efficiently collected, which is effective.

Hereinafter, as a specific example of the present invention, a result of collecting a scale based on the method of the present invention and measuring the amount of the scale will be described.

First, the steel material after the hot rolling is applied to an electronic balance (0.
Measurable (up to 200 g) size (thickness: 7 mm, width: 24 mm, length: 150 mm)
, And the surface was covered with a vinyl tape, leaving a length of 30 mm at the center.

This was set in a tensile tester, extensometers were set at both ends thereof, and a magnet wrapped with a medicine wrapping paper was fixed so as to face the exposed portion of the steel surface of the test piece.
At this time, the distance between the test piece and the lower end of the magnet was fixed at 1 mm, and the distance between the test piece and the upper end of the magnet was changed.
The scale recovery rate at that time (the recovery rate in the case of “the amount of weight loss of steel material = recovery scale amount” was set to 100%) was evaluated.

However, the chucks at both ends of the test piece were treated so that no indentation was left on the steel material. The result is shown in FIG. As can be seen from the figure, when the distance between the test piece and the upper end of the magnet is 3 to 5 mm, the recovery rate is almost 100%.

FIG. 3 shows the result of investigating the relationship between the scale thickness of the steel surface (measured before the tensile test) and the amount of peeling scale using a microscope with the distance between the test piece and the upper end of the magnet set to 4 mm. As shown in the figure, there is a clear correlation between the amount of exfoliated scale and the scale thickness of the steel surface, and it is also possible to evaluate the amount of scale generated in steel from the amount of exfoliated scale. It can contribute to a good evaluation.

As described above, according to the present invention, a very small amount of scale peeling can be measured with high accuracy, and this makes it possible to evaluate the scale peeling property of a steel material with high accuracy.

[0021]

As described above, according to the evaluation method of the present invention, a scale is peeled off from a test piece by applying a load to the test piece, the scale is attracted by a magnet, and the weight of the attracted scale is weighed and peeled off. The scale that has been peeled off from the steel specimen can be collected efficiently and at a high recovery rate because the steel is evaluated for its properties. However, even a small amount of steel is measured directly by the peeled scale itself instead of measuring the weight change of a heavy test piece as in the past, so a high-precision weighing machine can be used, and the highly accurate scale peelability Evaluation becomes possible.

Further, according to the present invention, errors due to chuck indentation when applying tensile strain by measuring the weight of a test piece as in the prior art can be eliminated, and a more accurate scale measurement can be performed. Sex evaluation methods have also been established.

Further, from the result of investigation of the relationship between the scale thickness of the steel surface measured before the tensile test and the amount of the peel scale, there is a clear correlation between the amount of the peel scale and the scale thickness of the steel surface. The scale generation amount of the steel material can be evaluated from the scale amount, and it can contribute to the quantitative evaluation at the time of material development for the purpose of scale control.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an embodiment of the present invention and showing a procedure for adsorbing and recovering a scale that has peeled and dropped from a strained test piece with a magnet.

FIG. 2 is a drawing showing a relationship between an interval between a test piece and an upper end of a magnet and a scale recovery rate.

FIG. 3 is a drawing showing a relationship between a scale thickness on a steel material surface and a peeling scale amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Test piece 2 Evaluated surface 3 Taping 4 Tensile tester 5 Extensometer 6 Magnet 7 Fixing jig

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-90141 (JP, A) JP-A-5-273115 (JP, A) JP-A-5-28417 (JP, A) 2136 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 19/04

Claims (1)

(57) [Claims] 1. A test piece, which is a material to be evaluated with taping at both ends, is subjected to a load by a tensile tester until a certain strain is obtained, and a scale peeled and dropped from the test piece until the test piece reaches the certain strain is magnetized. A method for evaluating scale peelability, comprising weighing the weight of the adsorbed scale and evaluating the scale peelability of the steel material by the weighed value.