Grain flow

In metal forming, grain flow describes the directional structure within a component that arises during the production and forming of the metallic material. During cold forming, the material undergoes plastic deformation, causing the grain flow to align with the flow of material and the resulting component geometry.

In contrast to machining, this structure is not cut through and interrupted by material removal during forming. As a result, a continuous grain flow that follows the component contour can be created or maintained.

A favourable grain flow can have a positive effect on the load-bearing capacity of components, particularly those subject to mechanical stress.

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Grain flow in cold forming
Grain flow: Questions and answers

Grain flow in cold forming

In cold extrusion, the material is plastically deformed by high compressive forces and guided precisely into the desired component geometry. The grain flow follows the flow of material and can align itself along the contours of the component.

In machining, by contrast, the desired geometry is produced by material removal. In this process, existing grain flows may be cut through or interrupted. In cold-formed components, however, the oriented material structure can also follow the component contour in geometrically stressed areas such as transitions, flanges, collars or thread profiles.

One example is the production of threads: in thread forming, the material is plastically displaced and the thread is produced without any material removal. In thread cutting, on the other hand, material is removed and the existing grain flow is cut through. The grain flow retained or redirected during forming can contribute to a higher mechanical load-bearing capacity of the thread.

However, the effect of the grain flow on the component’s properties always depends on the material, geometry, forming process and subsequent load.

Grain flow: Questions and answers

What is grain flow in metal?

In forming technology, grain flow refers to the directional structure of the metallic material, which is shaped by preceding manufacturing and forming processes. During forming, it aligns itself according to the material flow and the component geometry.
How does the grain flow change during cold extrusion?

During cold extrusion, the material undergoes plastic deformation. The grain flow is redirected in line with the material flow and can follow the resulting component contour. As the geometry is created by forming rather than by material removal, the material structure is not cut through as it is in machining processes.
What is the difference between cold forming and machining in terms of grain flow?

In cold forming, the component geometry is created through plastic deformation of the material. This allows the grain flow to follow the component contour. In machining, by contrast, the geometry is created by material removal, which can cut through existing grain flows.
How does the fibre orientation affect component strength?

A favourable grain flow that follows the component geometry can have a positive effect on a component’s mechanical strength. However, the actual influence depends on the material, geometry, degree of forming and type of loading.
How important is the fibre orientation in components subjected to high loads?

In components subjected to high mechanical loads, a grain flow that follows the component geometry can be advantageous. As the material structure is redirected during cold forming in accordance with the flow of material and is not cut through by machining, it can contribute to the mechanical strength of the component.

Grain flow

Grain flow in cold forming

Grain flow: Questions and answers

What is grain flow in metal?

How does the grain flow change during cold extrusion?

What is the difference between cold forming and machining in terms of grain flow?

How does the fibre orientation affect component strength?

How important is the fibre orientation in components subjected to high loads?