Dissertation > Excellent graduate degree dissertation topics show

Wrought Magnesium Alloy Welding by Laser Filling Wires and Laser-arc Hybrid Techniques

Author: LinTianXiao
Tutor: HuQianWu；GaoMing
School: Huazhong University of Science and Technology
Course: Digitized material forming
Keywords: Wrought Magnesium Alloy Laser filler wire welding Laser - arc hybrid welding Weld shape Microstructure Mechanical Properties
CLC: TG456.7
Type: Master's thesis
Year: 2009
Downloads: 122
Quote: 1
Read: Download Dissertation

Abstract


Magnesium alloy is a light alloy with high specific strength and specific stiffness, high shock resistance and excellent machining performance, an increasingly wide range of applications in the manufacturing industry. However, how to improve the performance of magnesium alloy welding is still important issues facing the development of magnesium alloy. In order to overcome the common welding defects, welding performance magnesium alloys, filler wire AZ31 wrought magnesium alloy laser welding and laser-MIG hybrid welding process research were carried out. The main research results are as follows: the laser process parameters on the deformation of the AZ31B-T5 magnesium alloy sheet laser filler wire weld morphology characteristics of the microstructure and mechanical properties of connector law. With the increase of the heat input, the weld cross-section by the inverted conical transition to the cylindrical surface, the root width increases as the laser power is increased or the reduction of the welding speed on the weld. To maintain the the wire feed point - spacing between 0.5 ~ 1mm laser beam, and the wire feed speed and welding speed ratio between 0.3 and 0.4, was beautiful, no obvious defects in the weld surface of the key. Weld grains mainly of fine dendritic equiaxed crystal, columnar crystal is generated near the fusion line, Mg-Al-Zn compound precipitated between the dendrite shaft. Joint tensile strength of 83% to 94% of the parent material. The stomatal is the major factor in reducing the tensile strength of magnesium alloy laser filler wire welding. System to study the wrought magnesium alloy AZ31-F 10mm thick plate laser-MIG hybrid welding process. The results show that the combustion is extremely unstable in the MIG welding magnesium alloy arc synergistic effect by compound welding heat source to achieve stable burning, to ensure the stability of a hybrid welding process and obtain superior to laser welding the weld shape. Composite weld mainly composed of dendrites during the precipitation of a Mg-Al-Zn compound. The upper arc area of ​​grain size and half the width of the melting zone is greater than the lower laser zone. Joint tensile strength up to 262MPa, for 97.8% of the parent material. The grain size and stomata number of the main factors to affect the joint tensile strength. Deformed magnesium alloy AZ31B-T5 of pure laser, laser filler wire and laser-MIG hybrid welding joint properties, microstructure and weld morphology was analyzed. The results show that relatively simple laser welding, laser filler wire and laser hybrid welding to improve weld surface defects on the obvious advantages, and can reduce the number of pore in the weld and a higher tensile strength of welded joints. Because the improvement of weld forming, laser welding head filler wire tensile strength up to 120% of the base metal. Filler wire and laser welding, laser-MIG hybrid welding heat input increases, the weld grain coarsening joint tensile strength decreased, the maximum tensile strength of 98% of the parent material.

Related Dissertations

  1. Research on Technology and Mechanism of Joining Cemented Carbide to Carbon Steel,TG454
  2. Structure and Characterization of Room Temperature Self-crosslinked Acrylonitrile-butadiene-styrene,TQ325.2
  3. The Research on Extrusion Parameters Through the Plate Billet of Magnesium Alloy,TG379
  4. The Microstructure Transformation and Life Analysis of T91/P91 Steel at Elevated Temperature,TG142.15
  5. SiC_p/6061Al Composite Fabricated by Liquid Phase Mechanical Stirring Casting,TG249.9
  6. Study on the Silicon-based Composites as Anode Materials for the Lithium Ion Batteries,TM912
  7. The Research of Watermelon Seed’s Rupture Mechanism,S651
  8. Artificial Stock Market-based Research on Investment Returns with Small Type Models,F832.51
  9. Alloy microstructure and mechanical behavior of fine grain 93W-4.9Ni-2.1Fe,TG146.411
  10. Research on the Properties and Microstructure of Rheo-diecasting Al-Si Alloy Based on Ultrasonic Preparing Slurry,TG292
  11. Studyon Microstructureand Property of Aluminum(Magnesium)Alloyvia Lost Foam Casting by Vibration Solidification,TG249.6
  12. Electrochemical Performance of La Doped Zn/Al-substituted α-Ni（OH）2 Prepared by Homogeneous Precipitation Method with Urea,TB331
  13. Process and Properties Research of the SiO2f/SiO2-BN Composites by Urea Route,TB332
  14. Modifying Effect of Nano-Inoculant on ZL109 Aluminum Matrix Composites,TB331
  15. In-situ Formation of TiB2 Particle by ELTA and the Effect of the Particle on the Microstructure and Properties of Al Alloy,TB331
  16. Study on the Properties of New Type TiC Composites,TB331
  17. Study on the Preparation and Mechanics Properties of the Porous Low-k MSQ Material,TB383.4
  18. Study on Integrated Forming Operation of Carbon Fiber/Epoxyresin Composite Cylinder,TB332
  19. The Research on Production Technology, Microstructure and Mechanical Properties of AZ31 Magnesium Alloy Thin Sheet,TG339
  20. Study on Ultrasonic Refinement of Several Commercial Magnesium Alloys,TG146.22
  21. Numerical Simulation and Experimental Study on Twin-roll Casting Magnesium Alloy Strip Process,TG339

CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Special welding > Laser welding
© 2012 www.DissertationTopic.Net  Mobile