Weldability
Weldability is a central term in welding technology that makes a statement about the achievement of the required quality of a welded component through welding production. The weldability of a component depends on the process. Weldability is the ability of a component made of a certain material to be welded under given production conditions and structural requirements in such a way that it can fulfill its intended tasks over the service life.
The weldability of a component depends on three equally important influencing factors:
Weldability relates to the material properties and is the material suitability for the use of certain welding processes. Here the technological properties, the chemical behavior and the mechanical quality values of the material to be welded are taken into account. The term "weldability" is often reduced to this material property. The less the material properties influence the weldability, taking into account the other conditions, the better the weldability of a material.
Welding possibility refers to the manufacturing possibilities. This includes the individual production processes , production means, quality assurance, control and also occupational safety. The less the material properties influence the weldability, taking into account the other conditions, the better the weldability of a material. Good welding possibilities are given under the existing manufacturing procedures if the welds can be carried out on a component without any problems.
Welding safety relates to the constructive influencing variables. On the one hand, the functional reliability must be guaranteed; on the other hand, the dimensioning should correspond to the expected loads and tensions. A construction has a high level of welding reliability if the component is little affected by the constructional influences during welding under the given material and manufacturing conditions.
Resistance spot welding
For resistance spot welding is the DVS -Merkblatt defined 2902-1: "spot weldability of a component is given, when a sufficient load of the spot welding joint can be achieved in consideration of an appropriate production process" . Since a wide variety of materials and material combinations are connected to one another with resistance spot or projection welding in a wide variety of dimensions, the weldability of the respective materials is of central importance. In order to produce a high-quality resistance spot welded joint, the choice of an adapted welding process (alternating or direct current), a suitable power source, the appropriate parameterization and the use of adapted electrodes (materials and shape) are essential. Thus, the "weldability" and the "weldability" are to be considered in close connection when a statement is made about weldability. Just as important is the consideration of the structural conditions. These relationships can be represented in so-called cause-effect diagrams .
Criteria for the weldability of resistance spot and projection welding are:
- the welding area,
- the electrode life,
- the material hardening, the surface properties, internal cracks, pores, cavities and other imperfections,
- Strength of the weld joint under given loads,
- Fracture formation under given loads,
- Resistance to stresses during component use due to corrosion , moisture , temperature .
Individual evidence
- ↑ DIN technical report ISO / TR 581: 2007-04: Weldability - Metallic materials - General principles , German version
- ↑ a b c d ISO / CD 18278-1 (draft): Resistance welding - Weldability - Part 1: General requirements for the evaluation of weldability for resistance spot, seam and projection welding of metallic materials
- ↑ DVS, resistance spot welding of steels up to 3 mm single thickness - overview , DVS-Merkblatt 2902-1, 2001