Crack controlling means for laser deposition formed metal parts

A technology of laser cladding and control methods, which is applied in laser welding equipment, metal processing equipment, manufacturing tools, etc., can solve the problems of laser cladding forming cracks and poor versatility, and achieve the reduction of residual thermal stress, crack reduction, The effect of eliminating residual stress

Inactive Publication Date: 2006-02-22
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Zhu Bolin et al. published "Research Status of Cracking of Laser Cladding Layer" in "Metal Heat Treatment" 2000, 7:1-4, but this method has poor versatility, and the adjustment of powder composition will have a certain impact on the cladding layer performance. The influence of suitable process parameters needs to be obtained through a large number of experiments
In further searches, no methods have been found to control laser cladding forming cracks by closed-loop control of molten pool temperature and introduction of ultrasonic vibrations

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] The 8-layer laser cladding forming test was carried out on the nickel-based alloy, the laser power was 1.5KW, and the scanning speed was 100mm / min. When the temperature closed-loop control was not adopted, when the cladding reached 4 to 5 layers, a crisp crackling sound could be heard; When the cladding forming contour closes the parts, the overlap of the cladding layer is seriously overheated and collapses, the formed parts are warped and deformed, and a large number of micro-cracks or even macro-cracks appear at the junction with the matrix; when the PID is used to control the molten pool temperature in a closed loop, The temperature distribution of the cladding layer is uniform, the surface precision is improved, and the cracks in the cladding layer almost disappear.

Embodiment 2

[0016] Carry out 8-layer laser cladding forming test on nickel-based alloy, laser power 1.5KW, scanning speed 120mm / min, introduce ultrasonic vibration device during forming process, vibration frequency 25KHz, and adjust the output power in the range of 150-500W, observe the ultrasonic vibration Effects on tissue and cracks. When the power of the ultrasonic vibrator is 150W, the microstructure of the nickel-based alloy formed by laser cladding is similar to the structure without ultrasonic vibration, which is composed of thick dendrites grown by epitaxial growth. The number of cracks within 100mm range is 10 under the microscope; When the vibration power was increased to 250W, the originally well-developed dendrites were broken and became short, the grains were obviously refined, and the number of cracks within 100mm was reduced to 6; as the vibration power was increased to 500W, the structure of the cladding layer The morphology has changed significantly, the dendrite branche...

Embodiment 3

[0018] An 8-layer laser cladding forming test was carried out on nickel-based alloy powder. The laser power was 1.5KW and the scanning speed was 120mm / min. Ultrasonic vibration was introduced during the forming process and PID was used to control the molten pool temperature in a closed-loop manner. The vibration frequency was 25KHz and the vibration power was 500W. The surface of the formed test piece is smooth without cracks.

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Abstract

The invention relates to a crack-controlling method of metal parts by laser melting formation in laser material processing domain, which comprises closed-loop control of fused bath temperature, which comprises the two specific steps of exerting closed-loop feedback control on fused bath temperature by using optical imaging system and PID control device with calorific radiation transmitted from melting zone and adjusting horsepower of laser, and introduction of ultrasonic vibration, which comprises the specific steps of introducing ultrasonic vibration under the piece of work when forming by laser melting. The invention can deduce residual stress and crack, improve structure and can be used in multiple relative domains such as forming, manding and surface peening by laser melting.

Description

technical field [0001] The invention relates to a method in the technical field of laser processing, in particular to a method for controlling cracks in the laser cladding forming process. Background technique [0002] Laser cladding forming technology is a new type of advanced manufacturing technology developed in recent years that integrates computer technology, numerical control technology, laser technology and material processing technology. This technology combines rapid prototyping technology and laser cladding surface strengthening technology, uses high-energy laser beams to form a molten pool on the metal substrate, melts the metal powder delivered to the molten pool by the powder feeding device and nozzle, and rapidly solidifies the cladding layer Forms a metallurgical bond with the substrate. By accumulating metal powder layer by layer, the rapid manufacturing of three-dimensional near-net-shape full-density metal parts is realized. Due to its advantages, laser c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C24/10B23K26/00
Inventor 邓琦林宋建丽陈畅源胡德金
Owner SHANGHAI JIAO TONG UNIV
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