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Method for prolonging tension-compression fatigue life of metal workpiece and workpiece manufactured according to same

A metal workpiece, fatigue life technology, applied in the field of mechanical manufacturing and processing, can solve problems such as fatigue fracture of metal workpieces

Active Publication Date: 2017-12-26
CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of this, the purpose of the present invention is to provide a method for improving the tensile and compressive fatigue life of metal workpieces and the workpiece produced by the method, which can solve the technical problem of fatigue fracture of metal workpieces in the product life cycle, and improve the tensile and compressive fatigue life of metal workpieces. Fatigue life, effectively avoiding the occurrence of safety and economic losses caused by workpiece fracture

Method used

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  • Method for prolonging tension-compression fatigue life of metal workpiece and workpiece manufactured according to same
  • Method for prolonging tension-compression fatigue life of metal workpiece and workpiece manufactured according to same
  • Method for prolonging tension-compression fatigue life of metal workpiece and workpiece manufactured according to same

Examples

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Effect test

Embodiment 1

[0050] A method for improving the tension and compression fatigue life of a metal workpiece is specifically applied to an embodiment of a fastening workpiece (a bolt is used as an example for fastening a workpiece), and includes the following steps:

[0051] In the length direction of bolt 1 (as attached figure 1 , 2 , 3 and 4 in the direction indicated by L), the bolt 1 is subjected to a strong tensile treatment, that is, a set tensile force that exceeds its yield strength but is lower than its tensile strength is applied. When the tensile force applied to the bolt 1 reaches the expected setting After the tension, the tension is removed to improve the fatigue characteristics of the bolt 1 in tension and compression. The time of the strong pulling treatment is to remove the tension at the moment when the expected tension is reached, or it can be held for a certain period of time after reaching the expected tension (referred to as holding time) and then the tension is removed.

[00...

Embodiment 2

[0059] A bolt 1 manufactured by the method described in Embodiment 1. The bolt 1 includes a bolt body 3 and a bolt head 2 provided at one end of the bolt body 3.

Embodiment 3

[0061] For bolt 1, select M10×85 grade 8.8 carbon steel bolts, M10×85 grade 8.8 carbon steel bolts have a yield strength of 37.1KN and a tensile strength of 46.4KN. A tensile force of 40KN is applied to the bolt 1 through a tensile machine, and the tensile force will be removed when the tensile force applied by the tensile machine reaches the expected tensile force (ie, the tensile force of 40KN). After 40KN strong tension treatment, under 5.5KN pre-tightening force, ±5.5KN alternating load conditions, compared to the untreated bolt 1, the tension and compression fatigue life of the bolt 1 after the strong tension treatment Get a 12-fold improvement.

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Abstract

The invention discloses a method for prolonging the tension-compression fatigue life of a metal workpiece and the workpiece manufactured according to the method. The method comprises the step that set tension higher than the yield strength and lower than the tension strength of the metal workpiece is applied to the metal workpiece in the operating state in the tension stress bearing direction. The tension applied to the metal workpiece is relieved after reaching the set tension so that the tension-compression fatigue characteristic of the metal workpiece can be improved. By applying the tension higher than the yield strength of the metal workpiece to the metal workpiece, pressure stress is formed on the stress concentration portion when the metal workpiece does not bear external force. By applying the tension, stress concentration formed on the stress concentration portion under the rated condition of the metal workpiece is weakened compared with stress concentration generated before the metal workpiece bears the tension. By means of the method for prolonging the tension-compression fatigue life of the metal workpiece and the workpiece manufactured according to the method, the technical problem of fatigue fracture of metal workpieces within the product life cycle can be solved, the tension-compression fatigue life of the metal workpiece is prolonged, safety loss, economic safety and the like caused by workpiece fracture are effectively avoided, and meanwhile metal workpieces having potential quality issues can be removed in advance.

Description

Technical field [0001] The invention relates to the field of mechanical manufacturing and processing, in particular to a method for improving the tension and compression fatigue life of a metal workpiece, and a workpiece produced by the method. Background technique [0002] As a metal workpiece with high local stress concentration, fasteners, such as bolts, are usually prone to fatigue damage under tensile conditions, which brings safety hazards and economic losses to the products they apply. At the same time, it is also very prone to fatigue damage to locally high-stress connection workpieces such as locomotive wheel pairs, welding workpieces, and workpieces with initial defects. Take bolts as an example. Bolts are mechanical parts that are widely used in various fields. As a common fastener, they are often used to fasten and connect two parts with through holes in cooperation with nuts. As we all know, most of the damage of bolts is fatigue damage, and bolts are parts with mul...

Claims

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Application Information

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IPC IPC(8): C21D7/02
CPCC21D7/02
Inventor 许倍倍张文辉严允
Owner CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST