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Welding seam shape design method for making amplitude-changing fatigue performance of welded joint the same as that of base material

A technology for welded joints and fatigue performance, which is applied to welding equipment, metal processing equipment, workpiece edge parts, etc., and can solve problems such as uncertain load spectrum, variable amplitude fatigue, and inconvenient joint design

Active Publication Date: 2020-09-01
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For constant amplitude fatigue, the bearing capacity of the base metal can be characterized by the conditional fatigue strength, but the actual working condition of the welded structure is often variable amplitude fatigue, and even the load spectrum is uncertain, which brings great inconvenience to the joint design

Method used

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  • Welding seam shape design method for making amplitude-changing fatigue performance of welded joint the same as that of base material
  • Welding seam shape design method for making amplitude-changing fatigue performance of welded joint the same as that of base material
  • Welding seam shape design method for making amplitude-changing fatigue performance of welded joint the same as that of base material

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specific Embodiment 1

[0075] according to figure 1 As shown, the present invention provides a welding seam shape design method that makes the fatigue performance of the welded joint the same as that of the base metal, including the following steps:

[0076] A welding seam shape design method that makes the fatigue performance of the welded joint the same as that of the base metal. When the base metal and the weld have no cracks, the following steps are included:

[0077] Step 1: Determine the ratio of the fatigue limit of the weld deposited metal to the base metal and the ratio of the tensile strength of the weld deposited metal to the base metal;

[0078] Step 2: According to the ratio of the weld deposited metal to the fatigue limit of the base metal and the ratio of the weld deposited metal to the tensile strength of the base metal, select the generalized matching ratio with the smallest value to determine the load used in the design;

[0079] Step 3: When the base metal and the weld have no cr...

specific Embodiment 2

[0139] The general form of load-bearing realization conditions such as welded joints is: the generalized mechanical concentration coefficient is not greater than the generalized matching ratio. Under the action of fatigue load, the bearing capacity of the component is characterized by the load P and the life N. The general form of this load-bearing realization condition is that the fatigue life of the welded joint and the smooth base metal are the same, and the equivalent matching ratio is the condition Fatigue strength matching ratio, when the load size changes, the equivalent matching ratio changes accordingly. That is to say, even if the load form is determined, under the action of fatigue load, the critical curve of the weld changes with the load, which is different from the case of static load.

[0140] In order to study the influence of the load size, the equal bearing idea can be equivalently expressed as, under the same load, the fatigue life of the weld metal is not l...

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Abstract

The invention provides a welding seam shape design method for making the amplitude-changing fatigue performance of a welded joint the same as that of a base material. For no crack of both the base material and a welding seam, by adjusting the geometric parameters of the welding seam to make the ratio of the stress of the welding seam to the base material be equal to the smaller numerical value ofthe ratio of the fatigue limit of welding seam deposited metal to the fatigue limit of the base material and the ratio of the tensile strength of the welding seam deposited metal to the tensile strength of the base material, the equal amplitude-changing fatigue load of the welding seam and the base material is achieved; and for cracks of both the base material and the welding seam, by adjusting the geometric parameters of the welding seam to make the ratio of the stress intensity factor of the welding seam to the stress intensity factor of the base material be equal to the smaller numerical value of the ratio of a stress intensity factor threshold value of the welding seam deposited metal to a stress intensity factor threshold value of the base material and the ratio of a critical stress intensity factor of the welding seam deposited metal to a critical stress intensity factor of the base material, the equal amplitude-changing fatigue load of the welding seam and the base material is achieved. While keeping the safety margin constant, the equal amplitude-changing fatigue bearing design can reduce the thickness of the base material and achieve lighter weight; and the thickness of the base material is kept unchanged, and the equal amplitude-changing fatigue bearing design can increase the safety margin and improve the bearing capacity.

Description

technical field [0001] The invention relates to the field of welding technology, and relates to a welding seam shape design method for making the amplitude-changing fatigue performance of a welded joint the same as that of a parent material. Background technique [0002] The development of high-strength steel is currently the main practice to reduce the weight of steel structures and ensure reliability, and to meet resource and environmental challenges. However, the bearing capacity of welded joints of high-strength steel (especially high-cycle fatigue bearing capacity) is lower than that of the base metal, and the tendency of brittle fracture is large, which greatly limits the application of high-strength steel in welded structures. In the case of static load, through complex preheating and postheating processes, developing special welding materials, or adopting low-matching welded joint static load and other bearing designs, the bearing capacity of welded joints can be the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K31/12B23K33/00
CPCB23K31/12B23K33/00
Inventor 董志波郭军礼周守振卢伟泽方洪渊
Owner HARBIN INST OF TECH