Method for evaluating macroscopic residual stress of steel wire

Abstract

The invention discloses a method for judging the macroscopic residual stress level of a steel wire by utilizing the change rule of the instantaneous tensile elasticity modulus of the steel wire along with tensile stress. According to the method, a function relationship between the yield ratio (yield factor) on the cross section of the steel wire and the instantaneous elastic modulus of the steel wire is established, and the macroscopic residual stress level of the steel wire and the yield ratio on the cross section under a certain nominal tensile stress can be calculated by measuring the instantaneous elastic modulus of the steel wire. The method comprises the steps of A, loading a tensile steel wire by stages by using a tensile testing machine; B, drawing an E-sigma relation curve of the load secant elasticity modulus of each level and nominal stress; C, determining the tensile elastic modulus ET of the steel wire in a residual-stress-free state, the nominal stress [sigma]1 for starting to yield in a section part area and the yield stress [sigma]Y of the whole section according to the E-sigma curve; D, calculating the maximum macroscopic residual stress [sigma]R of the steel wire according to a formula [sigma]R=[sigma]Y-[sigma]1; E, when [sigma] is greater than [sigma]1, obtaining that the tensile stress on the cross section of the steel wire reaches the yield area ratio; and F, modifying a common tensile testing machine and a loading program.

Description

technical field [0001] The invention relates to a silk macroscopic residual stress evaluation method and its application. Background technique [0002] During the process of drawing, heat treatment, straightening, etc., the steel wire generates residual stress inside the steel wire due to the action of external force and temperature. If the balance of residual stress is destroyed during use, it will cause elastoplastic deformation in the steel wire, resulting in changes in size and shape, and deformation of the steel wire such as twisting. At the same time, the residual stress also reduces the fatigue resistance, stress corrosion resistance and creep cracking resistance of the steel wire. In order to ensure the safety and reliability of the finished steel wire during use, the residual stress level of the finished steel wire should be evaluated and controlled. [0003] In production, experiments are generally used to test the residual stress level of steel wires. The commonl...

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Problems solved by technology

[0003] In production, experiments are generally used to test the residual stress level of steel wires. The commonly used destructive testing methods mainly include drilling method, strip method, grooving method, ring core method, peeling method, section method and crack method, etc. The commonly used nondestructive testing methods are: The methods mainly include X-ray diffraction method, neutron diffraction method, synchronous diffraction method, ultrasonic method and magnetic method, etc., but these methods have expensive equipment, complicated measurement procedures, high technical requirements, long measurement time, and high measurement costs. Need to go to a large institute for measurement and evaluation

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