Crack arrest method of alloy surface fine crack crack arrest method and device thereof

A micro-crack and alloy technology, applied in metal processing equipment, laser welding equipment, manufacturing tools, etc., can solve problems such as application limitations and difficult operation, achieve fatigue limit stress enhancement, realize recycling, and increase fatigue threshold Effect

Inactive Publication Date: 2008-08-13
JIANGSU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] However, the application of these methods is limited to a large extent either due to operational difficulties or the need for other complicated equipment to complete

Method used

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  • Crack arrest method of alloy surface fine crack crack arrest method and device thereof
  • Crack arrest method of alloy surface fine crack crack arrest method and device thereof

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Experimental program
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Effect test

Embodiment 1

[0033] Before the repaired aluminum alloy 2024 sample is cracked by laser, the oxide layer and pollutants on the surface of the alloy crack that affect the bonding force are removed by mechanical methods such as surface polishing, so as to increase the mechanical bonding surface and obtain higher bonding strength and durability. sex. Then apply a layer of glass film on the surface of the alloy as a crack stop patch, and coat a layer of black paint on the glass film. According to the damaged length of the crack is 5mm, when surface cracks appear on the surface of the alloy plate shown in Figure 1 , the pulse energy is 30J, the pulse width is 20ns, the spot size is 6mm, and the laser parameters are selected as the repetition frequency 1Hz for laser shock arrest. Figure 1 shows the schematic diagram of laser shock arrest. The neodymium glass laser emits pulsed laser beams through the lens to arrest cracks through the lens window; choose the arrest route A and the arrest route B (...

Embodiment 2

[0035] The sample is a TC4 alloy blade with a surface crack length of 1.7 mm. The surface is pretreated first, and then coated with glass film, and the surface of the TC4 alloy blade is subjected to laser shock arrest. The pulse energy is 20J, the pulse width is 22.5ns, and the repetition frequency is 0.5Hz for laser shock arrest.

[0036] After the surface of the TC4 alloy blade is subjected to the laser shock arrest test, the residual stress of the surface crack is measured by the X-350A X-ray stress analyzer of Hebei Est Stress Technology Co., Ltd. The distribution of the residual stress is shown in Figure 4 . It can be seen from the figure that the residual stress of the blade surface is compressive stress. Moreover, the stress level is high, the stress distribution is obvious, and the change trend of the stress starts from the surface and decreases linearly with the increase of the surface distance. Compared with the laser cladding repair treatment, the residual compress...

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Abstract

A crack arrest process and device thereof for removing fine cracks on alloy surfaces, relates to laser impulse processing application technique field. Oxide layers and pollutants on alloy surfaces which affect surface bonding force are removed to obtain good glue-joint strength and permanent stability; a flexible film is adhered to the alloy surface as a crack arrest patch, and a layer of black lacquer coating is applied on the crack arrest patch; laser pulse with following parameters: pulse energy of 15-40J, pulse width of 20-30ns, light spot size of 4-10mm, repetition frequency of 0.5-10Hz is selected to performing laser impact crack arrest according to damage status of the cracks; laser crack arrest is performed by selecting crack arrest route, and crack effects are inspected by using no-damage technique during crack arrest process. The invented method and device can increase alloy surface fatigue threshold value, the existing of residual compressive stress on metal surface after laser impulse enhances fatigue threshold stress on material surface greatly.

Description

technical field [0001] The invention relates to the technical field of laser shock processing applications, in particular to a method for arresting tiny cracks on the surface of an alloy, which is suitable for performing crack arrest and closing treatment on the surface of metal materials by using the mechanical effect of laser shock waves. Background technique [0002] In the production activities of human society, fracture, corrosion and wear are the three main failure modes of structural failure caused by mechanical parts and engineering components under different stress environments. Among them, fracture is an "explosive disease". Due to the suddenness of fracture, It will not only cause great loss of life and property, but also often lead to catastrophic accidents. Key components such as pressure vessels, drilling platforms, oil pipelines, nuclear reactors, engine casings, and aircraft landing gears that use metal materials at home and abroad have experienced fracture a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23P6/04B23K26/00C21D1/00
CPCB23P6/04
Inventor 任旭东张永康周立春周建忠冯爱新鲁金忠
Owner JIANGSU UNIV
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