METHOD OF TEST OF WELDED BLANK (VERSIONS) Russian patent published in 2010 - IPC G01N3/08 

FIELD: testing equipment.

SUBSTANCE: invention refers to investigation of strength properties of hard materials. Plane specimen is strained, it is preliminary cut from welded blank made of thin sheet or strip of ferrous or nonferrous metal with thickness up to 3.0 mm. Specimen with lateral arrangement of weld seam is gridded. Tests are performed till crack appears on specimen. Test result is recorded on stress-strain diagram, differences of mechanical properties of specimen cross-section are determined by distortion of sizes of grid segments after test. According to second version, specimen with lateral arrangement of weld seam is gridded - cells are of spheric form. Specimen is placed in pull-test machine, strained along weld seam of specimen. Simultaneously with determination of relation of force applied to specimen to its relative strain which is measured by sensors of test machine, appearance of distorted grid on strained specimen is continuously photographed. After achievement of limit value of homogeneous strain of specimen among arrayed data of test machine, difference of values of strain force applied during preceding and subsequent measurements is calculated by means of comparison of measurement results, as a criterion of achievement of limit admissible strain such measurement result is chosen after which determined difference rises sharply; and among all the photos, photo, which corresponds to this measurement in time, is chosen, on which grid distortion is measured for determination of admissible distortion of specimen material. Value of main logarithmic strain is calculated and diagram of ultimate strain for tested materials is plotted, this diagram with determined points is used for analysis of formability of parts from welded blank considering deviation of its strained distortion condition.

EFFECT: improvement of test accuracy.

4 cl, 9 dwg