Mechanical properties test sampling and processing We commonly use the wire cutting method and the water cutting method for the sample cutting method. When sampling the blank, water cooling prevents the sample from overheating and work hardening, which affects its mechanical properties and process performance. When sampling, we mark the blanks and specimens that do not affect their properties to ensure that the location and direction of sampling can always be identified.
Sampling by wire cutting method, the material is heated by molybdenum wire discharge to melt the body, so that the sample is separated from the whole. Near the melting area, the material has undergone a large temperature area that melts below the phase transition point, and we will leave enough cutting The allowance is to remove the material in the overheated area by processing the sample so as not to affect the performance of the sample. This allowance is specified as follows: generally, it should not be less than the thickness or diameter of the sample, and the minimum should not be less than 2mm. Because the water cutting sampling method uses high pressure water to cut the sample, it has no effect on the sample.
Processing requirements for tensile test specimens:
1. The mechanical properties of the sample should be prevented from cold deformation or heating during the machining process. Generally, cutting is appropriate, the depth of the feed should be appropriate, and it should be fully cooled. In particular, the depth of the last-pass cutting or grinding should not be too large, so as not to affect the performance.
2. For rectangular specimens, it is generally necessary to retain the original surface layer and prevent damage. The burrs on the sample should be removed, and the sharp edges should be rounded, but the radius should not be too large. The specimen is allowed to be relatively straight, but the corrective force should be prevented from having a significant effect on the mechanical properties.
3. After processing, the size and surface roughness of the sample should meet the requirements of relevant standards, and the surface should not have significant transverse tool marks, wear marks, mechanical damage, obvious cracks and other visible metallurgical defects.
Processing requirements for impact specimens:
1. The size of the standard sample is 10mm*10mm*55mm. When the thickness of the test material is less than 10mm and the standard sample cannot be prepared, a small size sample with a width of 7.5mm or 5mm can be used. The other dimensions and tolerances of the small size sample are the same as those of the standard sample with the corresponding notch, and the notch should be opened on the narrow side of the sample.
2. Due to the notch depth of the impact specimen, the radius of curvature of the notch root and the notch angle determine the degree of stress concentration near the notch, thereby affecting the impact absorption energy of the sample. These parameters must meet the relevant requirements for processing. In addition, the notch The quality of the bottom surface is also very important, the bottom should be smooth, there should be no machining marks and scratches parallel to the axis of the notch, and the roughness parameter of the bottom of the notch should not be greater than 1.6 μm.
3. The position of the specimen mark should not affect the specimen support and positioning, and should be kept away from the notch.
4. The shape and size of the impact specimen for the welded joint are the same as the corresponding standard specimen, and the axis of the notch should be perpendicular to the surface of the weld.
For various mechanical test samples, we have standards for reference. If you have sample processing and testing needs, please contact us for consultation.
