Method for Non-Destructively Determining Material Properties

Abstract

An approach to determining the crash dynamic behavior of structural castings made of a AlSi10MnMg alloy in a simple and cost-effective manner is provided. In this approach eddy current testing is carried out using a high-resolution measuring coil which is adjusted to the cast-specific conductivity.

Claims

1. A method for non-destructive determining of material properties of electrically conductive components, comprising the act of: moving an electromagnetic eddy current testing sensor at least one of on and near a surface of at least one sample cast component in a manner producing a varying magnetic field in the sample cast component; sensing with the sensor eddy currents in the at least one sample cast component; and displaying in human-readable form a measurement signal indicative of the eddy currents resulting in the at least one sample cast component from the varying magnetic field, wherein the electromagnetic eddy current testing sensor in a high-resolution eddy current sensor adapted to a conductivity of the at least one sample cast component.

2. The method as claimed in patent claim 1, further comprising the acts of storing a reference eddy current measurement signal from a reference cast component with known impact-dynamic and/or crash-dynamic deformability; displaying in human-readable form the reference measurement signal with a gain of the reference measurement signal adjusted to a reference location in the display; and determining the relative impact-dynamic and/or crash-dynamic deformability of the at least one sample cast component relative to the impact-dynamic and/or crash-dynamic deformability of the reference cast component by comparing the displayed measurement signal of the at least one sample cast component to the displayed reference measurement signal.

3. The method as claimed in claim 2, wherein a testing temperature at which the eddy current in the at least one sample cast component is sensed is the same as a testing temperature at which the reference cast component is sensed.

4. The method as claimed in claim 2, wherein the at least one sample cast component is a plurality of sample cast components, and a testing temperature at which the eddy current in at least two of the plurality of sample cast components is the same.

5. The method as claimed in claim 1, wherein a material of the at least one sample cast component is an AlSi10MnMg alloy having a magnesium content between 0.05 and 0.60 wt %.

6. The method as claimed in claim 5, wherein the magnesium content of the AlSi10MnMg alloy is between 0.14 and 0.45 wt %.

7. The method as claimed in claim 6, wherein the magnesium content of the AlSi10MnMg alloy is between 0.14 and 0.30 wt %.

8. The method as claimed in claim 1, wherein a material of the at least one sample cast component is an alloy in a cast state without prior active heat treatment, an alloy after single-stage heat treatment, or an alloy after two-stage heat treatment with at least one of water and air-quenching.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 shows a measurement display of a reference measurement in accordance with the present invention;

[0013] FIG. 2 shows a measurement display of a first alloy composition in accordance with the present invention; and

[0014] FIG. 3 shows a measurement display of a second alloy composition in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 shows a measurement display of a reference measurement on a measurement screen. For this, use is made of a cast sample of an alloy whose crash behavior is known from other testing methods, for example from a method of the type mentioned in the introduction under the prior art.

[0016] This cast sample undergoes eddy current testing in a manner known per se, the measurement sensor used being a high-resolution measurement coil that matches the cast-specific conductivity.

[0017] This measurement coil is moved over the cast sample at a variable distance, tilting back and forth, so as to produce a changing magnetic field. The measurement values produced in this manner are mutually aligned dot clusters which, as shown in FIG. 1, form a straight measurement line 1 that rises from left to right. This forms the reference line for the subsequent measurements.

[0018] The gain of the measurement values of the reference line 1 is set such that the measurement line runs through the center 2 of the crosshairs of the display in FIG. 1.

[0019] Then, a new cast sample with unknown crash behavior undergoes eddy current testing, the gain of the measurement values which was used during the reference measurement being retained.

[0020] This again produces dot clusters which form a measurement line 3 and 4 in FIG. 2. Both cases relate to a heat-treated alloy consisting of AlSi10MnMg with 0.2 wt % Mg, wherein the cast sample described by the measurement line 3 had a lower testing temperature than that described by measurement line 4. The cast sample that produced the measurement line 3 had the same testing temperature as the reference sample. This shows that the cast sample made of this AlSi10Mn alloy with 0.2 wt % Mg has a better crash behavior than the reference sample.

[0021] Choosing an elevated testing temperature results in the measurement line 4. This could suggest that the ductility in the event of a crash will be worse than that of the sample producing the measurement line 3, but in fact this is solely due to the different testing temperatures of identical cast samples.

[0022] FIG. 3 shows two other measurement lines 5 and 6. These are respectively a cast sample of a heat-treated AlSi10Mn alloy with 0.4 wt % Mg, wherein the cast sample producing the measurement line 5 had the same testing temperature as the reference sample and the cast sample associated with the measurement line 3. This shows that the cast sample according to measurement line 5 displays almost the same crash behavior as the reference sample, but worse behavior than the cast sample made of the AlSiMg alloy with 0.2 wt % Mg.

[0023] An elevated testing temperature corresponding to measurement line 6 again changes the measurement result, not due to the material but purely due to the temperature, toward a worse crash behavior.

[0024] Regarding the cast samples, it is immaterial whether these are samples from the melt or already finished cast components.

[0025] Conventional tensile testing of the same cast samples shows no different results, regardless of how high or low the testing temperature was. Therefore, this allows no conclusions to be drawn regarding crash-dynamic behavior, or the wrong conclusions would be drawn from such results.

[0026] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.