Ive got a question . I was talking to jack the other day about his new u joints and he said the the new forged ujoints will be a little stronger because of the grain structure.He said that billet runs a grain similar to wood whereas the forging the grain goes in all directions is this true? thanks for help in advance:D :D :D :D :D

Billet is machined out of a chunk of steel and forged is cast then machined down.

BILLET

Function: noun
Etymology: Middle English bylet, from Middle French billete, diminutive of bille log, of Celtic origin; akin to Old Irish bile landmark tree

a : a bar of metal b : a piece of semifinished iron or steel nearly square in section made by rolling an ingot or bloom c : a section of nonferrous metal ingot hot-worked by forging, rolling, or extrusion d : a nonferrous casting suitable for rolling or extrusion

FORGE

Function: verb
Inflected Form(s): forged; forg·ing
Date: 14th century
transitive senses

a : to form (as metal) by heating and hammering b : to form (metal) by a mechanical or hydraulic press with or without heat

Forging is the hammering or high pressure squeezing of either a billet or cast piece of metal. It is usually done above the critical temperature, but it can also be done cold. The grain structure is re-organized, but exactly how depends on the starting grain structure and how it is hammered. The grains tend to be aligned perpendicular to the direction of force.

With machined billet the grain lines are cut, creating a stress riser.

With a forgeing the piece comes out to near shape then machined. The grain in the forging will follow the geometry of the part. Stress can follow the grain lines without coming to a sudden end.

sorry guy's I gotta jump in here.........

a billet part is made from a piece of metal " as rolled" from the manufacturer ( steel mill / aluminum smelter etc...) it then is cut into it's shape by a machine ( lathe , mill , etc) that produces chips.

a forged part starts out as a piece of " as rolled " stock and is heated and then hammered into shape ( think blacksmith here, a horseshoe is an example of a forged part...... )
and yes the " grain " of the metal can be controlled to maximize strength along the net shape of the part

a cast part is made by pouring molten metal into a mold cavity ( this cavity can be in sand, wax, even steel ( die casting )

the machining of a casting or a forging is a secondary operation....
to bring it to whatever tolerance is required......
:)

www.metalinfo.com

If the metals in question are of similar alloy, the froged part will exceed the billet in strength. Forging does align the grain structure of the metal making it stronger. Some of the strongest stuff around is railrod track. It gets forged by millions of pounds many times a day.

The processes above may be used in conjuction, as well. A part may be first cast, then forged, and finally machined. The bottom line is, proper forging strengthens the metal.

Originally posted by reddwarf
If the metals in question are of similar alloy, the froged part will exceed the billet in strength. Forging does align the grain structure of the metal making it stronger. Some of the strongest stuff around is railrod track. It gets forged by millions of pounds many times a day.

It also, makes the grain structure smaller and more compact. There is also a point at which too much forging will generate brittleness, which could or couln't be desireable depending on what characteristics you are after. Its a ballance. You have to find a happy medium between ductility and brittleness, depending on what you are after.