Thermomechanical welding: a brief overview

TO thermomechanical Welding refers to those types of this process in which pressure is used together with thermal energy. Thermomechanical Welding allows for the establishment of a strong interatomic bond between two metals, with local heating, which allows for the parts to be joined together reliably.

Thermomechanical welding, methods and types

Thermomechanical welding has several ways of joining metal:

1. Forge welding is the oldest method of joining metals. It involves intensely heating one metal and joining it to another through the formation of interatomic bonds during plastic deformation with a forge hammer.

2. Resistance welding involves sequential processes: heating the welded parts to a flexible state and mutual plastic deformation. This type of welding can be:

• point;
• butt;
• relief;
• suture.

Spot welding. For convenience, the part is clamped in special clamps or the electrodes of a welding machine. A high current is then passed between the electrodes to heat the metal at the weld point to melting point. The current is turned off, and "forging" is applied by increasing the force of the electrodes' compression. A very strong joint is formed, the metal crystallizes, and the bond is complete.

Butt weld. For reliability and strength, welding is performed across the entire plane of contact. Thermomechanical welding In this way you can do:

• continuous flash welding;
• resistance welding.

In the first case, the process consists of a melting and upsetting stage. The workpieces are clamped in the machine's clamps, then the current is turned on and they are slowly brought together. During the melting stage, the ends of the workpieces touch at one or more points, forming bridges at the points of contact that immediately evaporate and explode. The explosion ejects small droplets of metal from the joint and vapor. These vapors serve as a protective atmosphere to reduce metal oxidation. As they are brought closer together, similar explosions occur, heating the workpiece in depth and gradually bonding it. This method shortens the time. During upsetting, it is necessary to increase the speed of bringing the workpieces together. Plastic deformation occurs by a specified allowance. This process is instantaneous. Thermomechanical welding Resistance welding involves passing an electric current through tightly pressed parts, after which the parts are heated in the welding zone to a plastic state and upsetting occurs. The current is turned off until upsetting is complete.

Relief welding. A relief is created on the part beforehand, creating raised areas. After the current passes through, these raised areas melt, causing plastic deformation, and the parts are pressed into each other. After the welding current is applied, the joint crystallizes.

Seam welding. Also known as roller welding, this method involves joining parts with a seam consisting of a series of weld spots that form a hermetically sealed joint.

3. Diffusion welding. Thermomechanical welding is carried out by diffusion, i.e. penetration of atoms of the metals being connected into each other at elevated temperatures (800⁰C). This requires a vacuum system with a shielding gas alternative. This method can be used to weld dissimilar metals.

Thermomechanical welding of metals

Thermomechanical welding of metals It is also used in other ways that allow for the strong connection of metal products. Advantages thermomechanical welding of metals are determined by the type of welding. For example, diffusion welding:

• different types of metals are welded;
• different thickness;
• even seams;
• low energy consumption.

Contact welding:

• welding speed;
• strength;
• environmentally friendly.

Thermomechanical welding of metals It is widely used in various fields of mechanical engineering, the automotive industry, instrument making and others.