Xin MA
,
Yiyu QIAN
,
Hongyuan FANG
,
F. Yoshida
材料科学技术（英）
By temperature normalization of the concept of equivalent damage stress proposed by Lemaitre, a new concept of relative damage stress has been put forward as the dominant mechanical factor for the failure of soldered joints under temperature cycling. Finite element numerical simulation results showed that the highest value of relative damage stress occurred at the high temperature hold time during temperature cycling history.
关键词:
Dongqing LI
,
Jun TAO
,
Qingguo Meng
,
Hongyuan FANG
材料科学技术（英）
By means of a newly developed non-contact detecting method, electronic speckle pattern interferometry (ESPI), a method of determining material property data during welding is studied. A TIG fixed-point welding process is modeled in which some achievements of simulation, such as the effect of welding pool on temperature field and nonlinear relation between convection coefficient and temperature, are all considered. In addition, by taking into account effect of heating rate, the workpiece is divided into near-weld zone and far-weld zone, which will be treated with different property values. When the displacement field computed with original property data is compared and matched with the experimental displacement field, which is measured by ESPI, these original data are adjusted properly. A group of raw properties are obtained and are corrected by statistical regression before they enter the simulation process again. By such a loop of “simulation-comparison-modification”, a set of property data that best satisfy the real condition are achieved finally. In such a way, a new method for measuring material properties during welding is found.
关键词:
Material properties
,
null
,
null
,
null
Xuesong LIU
,
Hongyuan FANG
,
Shude JI
,
Zhibo DONG
材料科学技术（英）
The technology of trailing peening is a kind of promisingly bran-new technology which can be used to control welding stress and distortion of Ti alloy thin plate. Control of TC4 Ti alloy thin plate welding stress and distortion under the condition of conventional welding and trailing peening is performed, respectively. The results show that the technology of trailing peening effectively reduces deflection and transverse shrinkage of thin plate weldment. The maximum deflection is decreased from 15 mm under the condition of conventional welding to 5 mm, while the weld transverse shrinkage is decreased from 0.5 mm to about 0.1 mm.
关键词:
Control of residual stress and distortion
,
null
,
null
Jianguo YANG
,
Jingwei WU
,
Hongyuan FANG
材料科学技术（英）
In order to understand the rate-controlling process for the interfacial layer growth of brazing joints brazed with active composite filler materials, the thickness of brazing joints brazed with conventional active filler metal and active composite filler materials with different volume fraction of A2O3 particulate was studied. The experimental results indicate although there are A2O3 particulates added into active filler metals, the time dependence of interfacial layer growth is t2 as described by Fickian law for the joints brazed with conventional active filler metal. It also shows that the key factor affecting the interfacial layer growth is the volume fraction of alumina in the composite filler material compared with the titanium weight fraction in the filler material.
关键词:
Composite filler material
,
null
,
null
,
null
Jianguo YANG
,
Hongyuan FANG
,
Xin WAN
材料科学技术（英）
Al2O3/Al3O3 joints were brazed with a new kind of filler materials, which were formed by adding Al2O3 particulates into Ag-Cu-Ti active filler metal. The results showed that the material parameters (the Ti content, Al2O3 particulate volume fraction) of the composite filler materials affected the shear strength of brazed joints. When the Ti content was 2 wt pct in the filler metal, the shear strength of brazing joints decreased with the increasing the volume ratio of Al2O3 particulate. When the Ti content was 3 wt pct in the filler metal, the shear strength of joints increased from 93.75 MPa(Al2O3p 0 vol. pct) to 135.32 MPa(Al2O3p 15 vol. pct).
关键词:
Composite filler material
,
null
,
null
,
null
