Grain Direction In Sheet Aluminum

Once the crystallites are elongated they appear as the.

Grain direction in sheet aluminum.

7075 is very notch sensitive. The grain direction is established during the metal rolling process. Two rollers compressing the hot metal cause the polycrystalline material to elongate in the direction of rolling. The grain direction is in the rolling direction of the sheet as it was being manufactured.

As a general rule the grain line must run perpendicular to the bend to avoid the potential for cracking or fracture. When sheetmetal is bend perpendicular to rolling direction grain rearranges. You can define a grain direction to use when calculating the bounding box for sheet metal parts. That has negligible impact on part strength.

Applying this to metal bending be it plate bending press braking or any other type of metal forming consideration must be given to the grain direction before any process is carried out. Where does grain direction come from. From the flat pattern properties we can select a new edge for the grain direction. The grain direction of the metal also contributes to the amount of springback that occurs in a bending operation.

Whereas bending parallel to rolling direction can lead to cracks because of destruction in grain structure. In addition to the new bounding box sketch there is a new option in the property manager for the flat pattern feature. The software determines the smallest rectangle bounding box that aligns with the grain direction to fit the flat pattern. When working with aluminum plate for example you need to pay close attention to whether you are forming with longitudinal or across transverse the grain direction.

During sheet metal processing rolling operation material grains are arranged in the direction of rolling. Only concern would be a rough grain can cause a stress riser if not polished out if a bending load is applied perpendicular to the grain. A plate s grains run parallel to the rolling direction. You ll now see that your flat pattern is generated based on one edge oriented parallel to the angled edge and the other obviously perpendicular to that in drawing the rectangle.

By default in my testing the bounding box aligns itself with the longest straight side. Strength will be the same in all directions. These grains vary in size and in orientation but are usually microscopic and directed from processing conditions. This has to do with the sheet grain direction.