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Bearing Steel Bar (52100): Crucible Steel Alloyed with Chromium
52100 is the steel of ball bearings: about 1 % carbon and 1.5 % chromium (ASM). The standard, ASTM A295, allows 0.93–1.05 % carbon and 1.35–1.60 % chromium. Here crucible steel is melted with chromium and a little manganese, cast, forged to bar and annealed soft for working.
Our method, not the factory one: factory 52100 is melted in an electric furnace and vacuum-degassed to meet the standard's limits on inclusions. A crucible melt can reach the composition, but only a lab test shows whether it is clean enough for bearings.
The picture: our drawing, crucible to bar.
Advanced
2 days
Instructions
1
1
Weigh the charge
Weigh the charge
For 1 kg: 981.5 g crucible steel of about 1 % carbon, 15 g chromium and 3.5 g manganese (our figures; see the last step). Use steel whose analysis you know.
Materials for this step:
Crucible Steel981.5 g
Chromium Metal15 g
Manganese3.5 gTools needed:
Digital Kitchen Scale2
2
Melt
Melt
Pack the steel, chromium and manganese in a covered clay crucible and melt it in the furnace. The alloy is fully liquid above 1450 °C.
Tools needed:
Clay Crucible - Deep
Brick Furnace
Bellows
Welding Gloves
Leather Apron
Safety Glasses3
3
Cast the ingot
Cast the ingot
Lift the crucible out with tongs and pour into a cast-iron ingot mould. Let it cool.
Tools needed:
Crucible Tongs
Ingot MouldWelding GlovesLeather ApronSafety Glasses4
4
Forge to bar
Forge to bar
Heat the ingot to a cherry-red heat and no hotter, and draw it out on the anvil to a round or square bar. Reheat when the colour drops; never hammer it cold.
Materials for this step:
Charcoal1 as requiredTools needed:
Blacksmith Forge
Anvil
Sledgehammer
Cross Peen Hammer
Blacksmith Tongs
Digital Caliper 6-InchWelding GlovesLeather ApronSafety Glasses5
5
Test the analysis
Test the analysis
Drill clean chips from the bar and have a lab analyse carbon, chromium, manganese, silicon, phosphorus and sulphur. Keep the bar only if it is within 52100 limits.
Tools needed:
Hand Drill
Glass Jars with LidsSafety Glasses6
6
Anneal soft
Anneal soft
In the oven, hold the bar at 793 °C (1460 °F) for 30 minutes, cool in the oven no faster than 500 °C an hour to 682 °C (1260 °F), then cool in air (Verhoeven's anneal).
Tools needed:
Heat Treating Oven
Thermocouple with ReadoutBlacksmith TongsWelding Gloves7
7
The charge
The charge
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Materials
4- 981.5 gPlaceholder
- 15 gPlaceholder
- 3.5 gPlaceholder
- 1 as requiredPlaceholder
Tools Required
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