# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DayX8nrvXiB
- **Gondola URL:** https://gondola.cc/posts/67970785-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/093b364440.jpg
- **Posted:** 2026-07-14T20:42:49.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

A 6000 ton press does not smash metal. It persuades it.

At room temperature a steel billet is a stubborn crystalline solid with a yield strength of several hundred megapascals. Heat it to 1200 degrees Celsius and the flow stress collapses to somewhere around 50 to 100 MPa, and the steel starts behaving less like a rigid body and more like extremely stiff plasticine. That single fact is what makes industrial forging possible.

The arithmetic is worth doing. Six thousand metric tons is roughly 59 meganewtons. Divide by a hot flow stress of about 80 MPa and you get a projected contact area of around 0.7 square metres. That is the real meaning of a tonnage rating. It is not a measure of violence, it is a budget: how much cross section the press can push through before it stalls.

What is happening inside the billet:

- Above roughly half the melting temperature in kelvin, dislocations climb and cross slip freely. The metal work hardens and softens at the same time.
- Dynamic recrystallisation nucleates entirely new, strain free grains at the old grain boundaries mid stroke. The microstructure is rebuilt while it deforms.
- Those fine, equiaxed grains follow Hall Petch: smaller grains, higher strength and toughness in the finished part.
- Compressive hydrostatic stress under the dies collapses casting porosity and welds internal voids shut by diffusion bonding.

This is why a forged crankshaft outlives a machined one. Casting leaves coarse dendritic grains and shrinkage voids. Machining a bar cuts straight through the grain flow, exposing fibre ends at the surface where fatigue cracks love to start. Forging bends that grain flow to follow the contour of the part, so the load path and the microstructure finally agree with each other.

Slow, deliberate, hydraulic. The press moves at a few tens of millimetres per second so the interior has time to deform with the surface rather than tearing away from it.

Strength is not added to metal. It is arranged.

#stemantics #forging #materialsscience #metallurgy #manufacturing

## Stats

- **Views:** 41,696
- **Likes:** 347
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- **Comments:** 4

## Tags

materialsscience, manufacturing, forging, stemantics, metallurgy

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