Semi-Steel

[VicParticipant @vic]

I was gifted a nice Elliott chuck some years ago and using it today I noticed that apart from the Elliott name it had "Standard Semi-Steel" on the badge. Anyone know what this is? Just interested. It's a lovely 5" four jaw independent for the money.

[VicParticipant @vic]

[Michael GilliganParticipant @michaelgilligan61133]

Vic,

Others have trod this path before: **LINK**

http://bbs.homeshopmachinist.net/threads/1478-Semi-steel-lathe-chuck

… I doubt if it's accurately "semi" but it seems to be a good thing.

MichaelG.

[Phil WhitleyParticipant @philwhitley94135]

Simply put, without getting into too much detail, the only difference between cast iron and steel is the carbon content. When cast iron is made with coke in a blast furnace it absorbs a huge amount of carbon, which makes it very stable, and very hard in compression, but brittle. Mild steel is cast iron with all but a small percentage of the carbon removed, and is fairly soft. By removing some of the carbon, or diluting it by adding scrap steel to the melt, you get a very tough metal, hard, but much less brittle.

[Ady1Participant @ady1]

They used semi-steel in the main drive wheel of the Acorn Shaper

It's meant to be tougher than cast iron

[Brian OldfordParticipant @brianoldford70365]

Because of its mechanical properties I have heard SG iron referred to as semi-steel, although it hasn't much difference to grey iron in its carbon content.

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