Views: 0 Author: Site Editor Publish Time: 2026-07-14 Origin: Site
Every week someone writes to us with the same problem: they bought standard steel balls, put one in the drill press, and destroyed two bits without making a dent. That is not a defective ball. A hardened bearing ball sits at HRC 60 or higher, harder than most cutting tools. If you need to drill, tap, weld, or rivet a steel ball, you need one that was never hardened, or was deliberately softened again. That is exactly what precision annealed steel balls are: the same tight roundness and diameter tolerance, minus the hardness, so your tooling can actually work on them.
We anneal balls at our own factory in CHANGZHOU/JIANGSU, and wholesale buyers order them for one of two reasons: to machine features into the ball, or to fasten it permanently into an assembly. This guide covers both, with real hardness numbers by material.
An annealed steel ball is a precision ball that has been heat treated to be soft instead of hard. Buyers and drawings call the same thing by different names: soft steel balls, unhardened steel balls, dead-soft balls, machinable balls. They all mean a ball whose hardness sits in the Rockwell B range rather than HRC 60+, so it can be cut, formed, and joined with ordinary tooling.
One thing "annealed" does not mean is imprecise. The balls are still headed, ground, and finished on the same lines as hardened balls, so roundness and diameter tolerances stay tight. You give up hardness and wear resistance, not geometry.
| Annealed (soft) balls | Hardened balls | |
|---|---|---|
| Typical hardness | HRB 55-95 (by material) | HRC 58-66 |
| Drill / tap with HSS tools | Yes | No (destroys tooling) |
| Weldable | Yes (best on low carbon) | Cracks, not recommended |
| Rivet / stake / cold form | Yes, deforms cleanly | Chips or shatters |
| Dent resistance under load | Low, will brinell | High |
| Bearing / high-cycle use | No | Yes |
| Can be hardened later | Yes (grade dependent) | Already hardened |
Annealing is a slow-cooling heat treatment. The balls go into a furnace, get held at temperature (roughly 650-800°C depending on the steel grade, and then cool down slowly with the furnace instead of being quenched. Slow cooling lets the microstructure settle into its softest, most uniform state and relieves internal stress at the same time.
For bearing-grade chrome steel we use a spheroidize anneal, which rounds the carbides in the steel into small globules. Spheroidized structure is the easiest condition to machine and the correct starting point if the part will be re-hardened after machining.
Two production routes exist. Either the ball skips the hardening stage entirely and is finished soft, or already-hardened balls are put back through an annealing cycle. Both arrive at the same place: a soft, stress-relieved, dimensionally stable ball.
| Material | Annealed hardness (typical) | Best for |
|---|---|---|
| Carbon steel 1010 / 1015 / 1018 | ~HRB 55-72 | Welding, riveting, lowest cost |
| Chrome steel 52100 / 100Cr6 / GCr15 | ~HRB 88-95 (≤HB 207) | Machine now, harden to HRC 60+ later |
| Stainless 420 | ~HRB 90-96 | Machinability plus rust resistance |
| Stainless 304 / 316 | ~HRB 75-90 | Corrosion resistance, non-magnetic needs |
The workhorse. Low carbon content makes these the softest, cheapest, and by far the best for welding: low-carbon steel joins cleanly without the cracking that plagues high-carbon grades. Typical uses are ball studs welded onto shafts, riveted pivots, lock cylinder pins, and counterweights. If corrosion is not a concern and nothing needs to be re-hardened, start here.
The clever one. Spheroidize-annealed bearing steel machines easily at HRB ~90, and after your drilling or grooving is done, the finished part can be quench-hardened to HRC 60-66, full bearing hardness. This "machine soft, harden after" workflow is how custom grooved balls, drilled detent balls, and modified bearing components get made. Order the same grade annealed and hardened from one factory and the chemistry matches perfectly.
When the finished part lives in a damp or washdown environment, anneal a stainless grade instead. Annealed 420 machines well and can be re-hardened to about HRC 50-55 afterward; we covered that grade in detail in our 420 vs 440C comparison. A detail worth knowing about the 300 series: standard cold-worked 304/316 balls are slightly magnetic, but fully annealed 304/316 balls are essentially non-magnetic. If your application needs a soft AND non-magnetic ball, annealed 304 or 316 is the specific answer, and few buyers know to ask for it.
Drilling and tapping:Standard HSS drills and taps handle annealed balls without drama. That opens up threaded balls for handles, knobs, and levers, through-holes for pins and cables, and blind holes for press-fit magnets. Try any of this on a hardened ball and you will be shopping for new tooling instead.
Welding and brazing:Annealed low-carbon balls spot-weld and projection-weld cleanly onto brackets, shafts, and sheet metal, making instant pivots, stops, and contact points. Hardened high-carbon balls crack at the weld; annealed low-carbon balls do not. This alone drives a large share of the annealed ball orders we ship.
Riveting, staking, and cold forming:A soft ball deforms instead of shattering, so it can be staked into a hole, swaged down in diameter, coined with a logo, or flattened into a custom contact. The ball becomes a preform, a cheap and perfectly round starting shape for your own forming operation.
Machine now, harden later:Cut your features while the steel is soft, then send the finished part through hardening. With annealed 52100 you end at true bearing hardness; with annealed carbon steel you can case-harden the surface. You get geometry that would be impossible or expensive to cut at HRC 60.
We would rather tell you this now than after a warranty claim. A soft ball has low dent resistance: put it under real load in a bearing race or a high-pressure check valve and it will brinell, flatten, and fail. Do not use annealed balls, in their soft state, for bearings, valve seats under pressure cycling, grinding media, or ball transfer units. Those jobs belong to hardened chrome steel or 440C. The exception, as above, is when the annealed ball is only a starting point and the finished part gets hardened before service.
Material grade: e.g. AISI 1015, 52100/GCr15, or 420. "Annealed steel ball" alone is ambiguous; the material decides weldability and re-hardening behavior.
Condition and hardness limit: write "annealed / soft, max HB 207" or "max HRB 95". A number on the drawing means the hardness certificate can be checked against something.
Diameter and precision grade: nominal size plus grade per ISO 3290, e.g. "Ø8 mm G100". Annealed balls hold precision grades too; just say which one you need.
Quantity and any secondary ops: if we are drilling, tapping, or flattening the balls for you, put the feature drawing on the same PO.
Send those four lines and any factory can quote you accurately the same day.
Materials: carbon steel 1010/1015/1018, chrome steel 52100 (100Cr6/GCr15), stainless 420/304/316
Sizes: 1 mm- 0.8 mm
Hardness: certified per batch; custom hardness ranges available on request
Secondary operations: drilling, tapping, and flats available in-house
Packaging: Packaged in cardboard boxes, then placed inside wooden crates.
1.Can you drill and tap an annealed steel ball?
Yes. That is the main reason annealed balls exist. At HRB-range hardness, standard HSS drills and taps work normally. Hardened balls at HRC 60+ cannot be drilled with conventional tooling.
2.What hardness are annealed steel balls?
It depends on the material: roughly HRB 55-72 for annealed carbon steel, HRB 88-95 for spheroidize-annealed chrome steel (52100), and HRB 90-96 for annealed 420 stainless. Always confirm the hardness certificate for your batch.
3.Can annealed steel balls be hardened after machining?
Yes, if you chose the right grade. Annealed 52100 chrome steel re-hardens to HRC 60-66, annealed 420 stainless to about HRC 50-55, and low-carbon steel can be case-hardened. Annealed 304/316 cannot be hardened by heat treatment.
4.What is the difference between annealed, soft, and unhardened steel balls?
In practice, nothing. Annealed, soft, dead-soft, and unhardened all describe balls supplied without the final hardening treatment. On a drawing, "annealed" plus a maximum hardness number is the unambiguous way to say it.
5.Are annealed steel balls magnetic?
Annealed carbon steel, chrome steel, and 420 stainless balls are all magnetic. Annealed 304 and 316 stainless balls are essentially non-magnetic, unlike their cold-worked (non-annealed) versions, which pick up slight magnetism.
