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Tensile Performance Test
Before the test, calibrate the test equipment to ensure the accuracy of the test data; prepare the specimen, mark the original distance; set the zero point of the test force to ensure that the force measurement system should not change during the test; choose the appropriate fixture to ensure that the clamped specimen is subject to the role of axial tension. The test begins, the specified rate of the specimen tensile, until the specimen breaks, pay attention to good data recording. Determination of tensile strength: tensile strength is the corresponding maximum force corresponding to the stress.
Determination of Upper Yield Strength: This can be measured from a force-extension graph or a peak force display, and is defined as the stress corresponding to the maximum force value before the force first drops. The upper yield strength is calculated by dividing the force by the original cross-sectional area of the specimen.
Determination of elongation at break: The fractured portions of the specimen shall be carefully mated together so that their axes are in the same straight line, special measures shall be taken to ensure that the fractured portions of the specimen are in proper contact and the specimen shall be measured at the post-break mark and the elongation at break shall be calculated in accordance with the formula.
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Flattening performance test
Place the specimen between two platens of the testing machine, note that the edges of the specimen are allowed to be rounded or chamfered by filing or other methods; the width of the platen should be more than the width of the specimen after flattening. Move the platen along the direction perpendicular to the longitudinal axis of the tube for flattening, the movement rate of the platen should not exceed 25mm/min. After the test, observe the specimen, in the case of not using a magnifying glass, if there is no visible crack should be assessed as qualified; if only in the corners of the specimen of the slight crack should not be used as a basis for judgment of waste.
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Uniformity test of galvanized layer
The test of galvanized layer uniformity adopts copper sulfate impregnation method. Specimen surface oil should be removed, and then wipe clean with a clean soft cloth. The specimen should be cut end down, impregnated in the solution length should not be less than 100mm, in the copper sulfate solution for five consecutive dipping. During the test, the temperature of the specimen and the solution should be kept in the specified range, and no stirring is allowed. The specimen should be impregnated for 1min each time, and should be cleaned in flowing water immediately after removal, and the black precipitate should be cleaned up with a soft brush and then dried with a soft cloth. Except for the last dipping, the specimen should be immediately re-immersed in the solution. Note that the test solution should be discarded after 20 dips of the specimen and should not be used.
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Determination of galvanized layer weight
The weight of galvanized layer is determined by antimony chloride method. The surface of the specimen is not allowed to have rough surface and zinc tumors exist, and the surface of the specimen should be washed with pure solvent, then drenched with ethanol and washed with water, and then varnished on the end surfaces of both ends of the specimen, and dried sufficiently. Weigh the specimen with a balance, immerse the specimen in the test solution, one specimen at a time, the liquid level should be higher than the specimen. The temperature of the solution should be no greater than 38°C during the measurement. Remove the specimen when the occurrence of hydrogen in the solution becomes minimal and the galvanized layer has disappeared. Rinse the specimen in water and dry it with cotton or a clean cloth, and weigh it on the balance after it is completely dry. After the specimen is stripped of the zinc layer, the outer and inner diameters shall be measured in two mutually perpendicular directions at the end of the specimen, and the average value shall be taken as the actual outer and inner diameters respectively. The specimen solution can be reused if the zinc layer can be easily removed.
