W. Guo
,
J.T. Niu
,
J.F. Zhai
金属学报(英文版)
Non-interlayer liquid phase dissusion welding (China Patent) and laser welding methods for aluminum matrix composite are mainly described in this paper. In the noninterlayer liquid phase dissusion welding, the key processing parameters affecting the strength of joint is welding temperature. When temperature rises beyond solidus tem perature, the bonded line vanishes. The strength of joint reaches the maximum and becomes constant when welding temperature is close to liquid phase temperature. Ox- ide lm in the interface is no longer detected by SEM in the welded joint. With this kind of technique, particle reinforced aluminum matrix composite Al2O3p/6061Al is welded successfully, and the joint strength is about 80% of the strength of composite (as-casted). In the laser welding, results indicate that because of the huge speci c surface area of the reinforcement, the interfacial reaction between the matrix and the reinforcement is restrained intensively at certain laser power and pulsed laser beam. The laser pulse frequency directly affects the reinforcement segregation and the rein- forcement distribution in the weld, so that the weldability of the composite could be improved by increasing the laser pulse frequency. The maximum strength of the weld can reach 70% of the strength of the parent.
关键词:
non-interlayer liquid phase dissusion welding
,
null
Y. P. Kathuria (Laser X Co. Ltd. Chick - shi Aichi - ken 472
,
Japan)
金属学报(英文版)
With the established technique of laser in science and industry, its applications hare become diversified in the automotive welding.Two potential lasers CO2 and Nd - YAG operating in the i. r. region hare been applied in various demains covering different spectrum of welding,ranging from dissimilar matal to aluminium alloy welding.These lasers considered as thermal processing tools offers an advantage of the keyhole welding offered by the electron beam where the energy is transferred from the surface by the keyhole formation. with the incorporation of these lasers as a flexible thermal processing tool,it has become essential to use them optimally through feedback with planning and constructional rules.Based upon the modulation and duty cycle variation,a simulation technique is demonstrated which enable us to estimate the processing results and determine the characterisitcs of the fabricated part. From the giv- en provess parameters such as haer power, focus radius,processing speed /interaction time and materi- al characteristics, one can optimize the welding condition etc. through the simulation process. In the present work the laser simulation process in welding were carried out with Al- alloy A 5052 of various thickness by using a multiwave high power Nd - YAC lasers.The simulated weld conditions resulted in better utility of the lasers with increased efficiency and better quality. The use of simuation method helped in the designing and prediction of welding technology, which reduced the rejection rate as well as the cost of production.
关键词:
easer beam welding
,
null
,
null
,
null
Science and Technology of Welding and Joining
A numerical modelling of the welding arc and weld pool is established for moving argon shielded gas tungsten arc welding to systematically investigate the effect of the active element oxygen and the welding parameters on the Marangoni convection and the weld shape using FLUENT software. The different welding parameters will change the temperature distribution and gradient on the pool surface, and affect the strength of Marangoni convection and the weld shape. Under high oxygen content, the weld depth/width (D/W) ratio substantially depends on the welding parameters. A high welding speed or large electrode gap (arc length) will make the weld D/W ratio decrease. The weld D/W ratio initially increases and then remains constant around 0.5 with the increasing welding current. When the oxygen content is lower, the weld D/W ratio decreases with the increasing welding current. However, the weld D/W ratio is not sensitive to the welding speed or electrode gap. The predicted weld D/W ratio agrees well with the experimental results.
关键词:
Numerical simulation;Oxygen;Welding parameter;Marangoni convection;Weld shape;type-304 stainless-steel;marangoni convection;activating flux;flow;patterns;oxide fluxes;gta;penetration;metal;shape;oxygen
LIANG Yong LI Ruiguo Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
ChinaInstitute of Corrosion and Protection of Metals
,
Aademia Sinica
,
Shenyang
,
110015
,
China
材料科学技术（英）
Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.
关键词:
laser
,
null
,
null
,
null
,
null
H. Y. Zhao
,
A. L. Lu
,
Q. Y. Shi and F. Yan (Welding Division
,
Department of Mechanical Engineering
,
Tsinghua University
,
Beijing 100084
,
China)
金属学报(英文版)
T-joints are widely used in ship manufacturing and other welding structures.The welding residual stress and deformation hare significant influence on failure and service life in welding structures.By us- ing of 3D thermal elasto - plastic FEM, the temperature fields,stress fields and deformation of weld- ing processes on T - joints are analyzed in this paper.The moving heat source is considered in the com- putation. Moreover, weld metal filling and multiple - pass welding are simulated using activate/deac- tivate ability.For avoiding "locking" in full integration elements of welding computation,the re- duced intergration elements are used in weld area.The nonlinear FEM analysis program MARC is used to complete the computations, as well as its user subroutines that are programmed to develop the special techniques needed in the simulation of welding process.Some different welding procedures are com- pared, and the welding residual stress and deformation are discussed in details.
关键词:
welding
,
null
,
null
,
null
,
null
Jitai NIU
,
Zhonghong LAI
,
MuZhen WANG
,
Liming LIU
,
Lin WU
材料科学技术（英）
The effects of laser welding parameter on strength of welded joints were studied. The mechanism for loss of joint strength was analyzed. It was pointed out that an important factor affecting joint strength is the reaction between matrix and reinforced phase. On the basis of this, the concept of critical Si activity alpha ([si]min) was proposed. Using appropriate welding parameters and Si activity, high quality laser welded joints in an aluminum matrix composite SiCW/6061A1 can be successfully obtained.
关键词:
Wei GUO
,
Qingchang MENG
,
Jitai NIU
,
Xinmei ZHANG
材料科学技术（英）
In this paper, a new method for welding SiCp/101A was put forward. It is LPI (liquid-phase-impacting) diffusion welding. Through LPI diffusion welding SiCp/101A aluminum, the effect of welding parameters on the welded joint property was investigated, and the optimal welding parameters were brought forward at the same time. The microstructure of joint was analyzed by means of optical-microscope, scanning electron microscope in order to study the relationship between the macro-properties of joint and the microstructure. The results show that LPI diffusion welding could be used for welding aluminum matrix composites SiCp/101A successfully.
关键词:
Aluminum matrix composite
,
null
,
null
