Language
Process parameters of diffusion welding machine [DW03]
Dec 20,2023
Process parameters of diffusion welding machine
- Temperature
Temperature is an important technological parameter of diffusion welding. Small change of temperature will cause great change of diffusion welding speed. In a certain temperature range, the higher the temperature, the faster the diffusion process, and the higher the strength of the obtained joint.
From this point of view, it is better to choose higher diffusion welding temperature. However, the heating temperature is limited by the metallurgical characteristics such as high-temperature strength, phase transformation and re-crystallization of the workpiece and fixture. And when the temperature is higher than a certain value and then increased, the joint quality is not much improved, sometimes decreased.
For many metals and alloys, the temperature of diffusion welding is 0.6 to 0.8Tm (K) , Tm is the melting point of base metal. For diffusion welding with liquid phase, the heating temperature of diffusion welding with liquid phase is slightly higher than the melting point or eutectic reaction temperature of the inter-layer material. The isothermal solidification and homogenization diffusion temperature of liquid phase can be decreased slightly after filling the gap. If the diffusion welding machine is equipped with infrared thermometer, it is able to control the temperature well.
- Pressure
When other parameters are fixed, a better weld joint will come by the use of a higher pressure. The upper limit of pressure depends on the limit of total deformation of welding parts, equipment tonnage and so on. For diffusion welding of dissimilar metals, it is important to reduce or prevent the diffusion holes by using larger pressure.
Other than Hot Isostatic Pressing diffusion welding, usually the diffusion welding pressure is 0. 5 to 50 MPa. A lower pressure may be selected for diffusion welding where a liquid phase is present. When the pressure is too high, in some cases it may cause the liquid metal to be extruded, resulting in the metal joint composition out of control.
Because the diffusion pressure has little influence on the second and third stages, it is allowed to reduce the pressure in the later stage in order to reduce the deformation of the workpiece
- Diffusion time
Diffusion time refers to the time that the workpiece remains at the welding temperature.
During the welding time, the diffusion process must be completed to achieve the required strength. If the diffusion time is too short, the joint strength can not reach the same strength as the base metal. But the high temperature and high pressure lasting time can not improve the joint quality, but will make the base metal grain grow up. For the joints which may form brittle inter-metallic compound, the diffusion time should be controlled in order to control the thickness of brittle layer so as not to affect the joint performance.
Diffusion welding time is not an independent parameter, it is closely related to temperature and pressure. When the temperature is high or the pressure is high, the diffusion welding time can be shortened.
For diffusion welding with inter-layer, the welding time depends on the thickness of inter-layer and the requirement of micro-structure uniformity of butt joint (including the allowance of brittle phase).
In the actual welding process, the welding time varies in a very wide range. A few minutes of welding time is sufficient when one process parameter is used, and several hours when another process parameter is used.
Related News
Wuxi HAIFEI Intelligent Equipment Co., Ltd.
Wuxi HAIFEI Welding Equipment Co., Ltd.
Add: 28 Shuiyun Road, Yuecheng, Jiangyin, Jiangsu Province, China. (Postal Code: 214404)
Mobile: +86 18915302352
Email: wushijie@jshaifei.com