How to tell cast iron or steel

old

Well-known Member
So I have a guy who wants me to do some welding for him. He say it is a cast iron pulley. But before I start I'd like to know which it is. At this time not sure what all he needs done so not sure what I'll be doing or how I'll be doing it
 
(quoted from post at 21:38:00 09/21/18) So I have a guy who wants me to do some welding for him. He say it is a cast iron pulley. But before I start I'd like to know which it is. At this time not sure what all he needs done so not sure what I'll be doing or how I'll be doing it

I always use a drill bit, 1/4" or so and drill a hole about equal depth. You will get a graphite like powder in cast iron or chips in cast steel.
 
Old just use the grind test. Cast iron will give off orange colored sparks that are not very lively. Steel will give off brighter yellow sparks with more volume and activity.
 
Hit it with a hammer. If it breaks it is cast iron if not it is steel.


Kind of like the old Chevy cam shafts. Drop them, if it break it was good, if it did not break it was no good anyway.


Ha HA
 
If it broke with a jagged crack that looks grainy and gray, that already pretty much already tells you it's cast iron.

A steel pulley would be thin, and if it "broke" it would be a fatigue fracture from flexing, IMHO.
 
old; You might be thinking of the difference between mild steel and stainless steel. Stainless is generally non-magnetic or only weakly magnetic, depending on the specific composition.

Stan
 
You could do it the hard way.................

Grey cast iron is 442lb/cu ft
Steel, cast or rolled is 490lb/cu ft

So you could determine how many cubic feet the pulley displaces by measuring how much water it displaces when dropped in a bucket of water.
Then you can multiply the cu ft displacement by the weights above.
One or the other computations should be a mathematical match to the actual weight of the pulley via a good scale.
 
Grab a cutting torch. If it's cast steel it will cut easily with a torch. Cast iron, stainless or Aluminum won't. Grinding, drilling and other methods also works, torch is easiest for me.
 
If you look into the bore of the pulley Iron will have a surface that will show small pits that will be dark. These will be scattered throughout the bore as well as the key slot. Steel will have a more uniform appearance and would be a bit more shiny.

The hub of the pulley is the heaviest section of the part and it will have the largest grain size on the part due to slower solidification in the mold. The hub bore is the best place to look.

My bet would be that if this pulley is a casting it would more than likely be cast iron. It's cheaper than steel because of raw material costs and the pouring temperatures are much lower than steel alloys and it has better wear characteristics.

Our foundry specializes in steel but we have cast iron alloy in the past. Take a look at our website. You may find it interesting
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