Joint preparation
Edge preparation is the mechanical or thermal working of the workpiece edges before welding to create a flawless joint geometry. This prevents porosity and improves weld strength.
Physical-Chemical Mechanism of Action
Joint preparation reduces the surface roughness of the workpieces, resulting in a more accurate groove shape. Mechanical preparation like grinding or buffing removes metal traces and impurities. Thermal preparation like laser or irradiation increases surface energy, leading to a better weld bond.
Metallurgical Relevance & Welding Risks
Insufficient joint preparation can lead to porosity and lack of fusion in the weld pool. This increases the risk of cracking and reduces weld strength. Careful preparation, however, improves toughness and the mechanical behavior of the joint.
Workshop Practice & Instructions
For successful joint preparation, follow these steps:
• Mechanical preparation: The workpiece edges should be smooth and free of metal traces and impurities. This can be done by grinding, buffing, or polishing.
• Thermal preparation: Thermal surface treatment like laser or irradiation increases surface energy and improves bonding properties. Temperature should be controlled according to the material and welding process.
• Preparation control: Quality of joint preparation should be checked regularly to ensure no porosity or lack of fusion occurs.