BS EN ISO 4506:2018 pdf download – Hardmetals – Compression test (ISO 4506:2018)
This document specifies a method of determining the ultimate strength and proof stress of cemented carbide under uniaxial compressive loads.
2 Normative references
There are no normative references in this document.
3? Terms? and? definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
Axial loading of a test piece, placed between two cemented carbide or pcd (polycrystalline diamond) coated cemented carbide bearing blocks at room temperature, until the intended deformation occurs or until the test piece fractures.
5 Symbols and designations
Table 1 shows symbols and designations.
The test piece shall be affixed between two well-centred and rigidly secured cemented carbide anvils with a hardness not less than 1 800 HV. These contact surfaces shall be perpendicular to the loading axis and parallel to each other within 0,5 µm/mm. An example of a suitable anvil is given in Figure 1.
7 Test piece
7.1 The dimensions of the test piece shall conform to Figure 2. The end faces and the cylindrical surfaces of the enlarged ends shall be ground. Other surfaces should not be ground. (Grinding or polishing may affect the result of the test.) 1)
7.2 The minimum diameter of the test piece shall be measured with an accuracy of ±0,02 mm. 8 Procedure 8.1 Rate of stress increase The rate at which the load is applied shall be as unifor
m as possible, and any changes in this rate shall be made gradually and without shock. The rate shall not exceed 8 000 N/s, corresponding approximately to 100 N/(mm 2 × s). 8.2 Determination of proof stress
8.2.1 The proof stress, for example the 0,2 % proof stress, is determined according to Figure 3. This method is based on the fact, valid for almost all metals, that if a load is removed after the elastic limit, D, has been exceeded, the load-compression curve will follow a linear path that is roughly parallel to the loading curve below the elastic limit.
8.2.2 Determination of proof stress using the graphic intersection method is carried out as follows.
18.104.22.168 Apply a pre-load not greater than that required to keep the test piece positioned properly in the machine.
22.214.171.124 Determine the stress-strain curve. Because of the shortness of the test zone and the hardness of the material, practical difficulties are involved in measuring changes in length using displacement gauges of the clamp-on type (extensometers) or using a laser extensometer. It is recommended that changes in length be measured using a resistive strain gauge. Two or three gauges should be applied symmetrically at the centre of the test zone. The active length of the gauges should not exceed 8 mm. The results obtained represent an average of the change in length of the test zone.
126.96.36.199 On the graph thus plotted (Figure 3), make OB equal to the specified residual strain (offset), and draw a line BA from B parallel to OC. Ordinate F C of intersection point Q has the value F cq and represents the load that corresponds to the proof stress. It is sometimes difficult to ascertain the direction of line OC from a graph; in such cases, this line can be drawn on the basis of an agreed value of the Young’s modulus.BS EN ISO 4506 pdf download.