The 2014 Alltrade homepage listed stainless steel solid round bar as its own bin, next to sheet, angle, channel, pipe and tube. That is still how a Melbourne merchant thinks. Bar is not a leftover from a plate. It is a rolled or drawn product with its own tolerances, its own finish, and its own way of failing if you treat it like a stick of mild steel.
This essay is the specification for Australian trade work: pins, shafts, threaded studs, bollard cores, machine parts, and the odd handrail that should have been tube. If you need a hollow, go to stainless steel tube versus pipe. If you need a folded section, stay with custom-cut stainless steel in Australia.
What “round bar” actually is
Solid stainless round arrives as:
- Hot-rolled, annealed and pickled (HRAP) — a dull, slightly scaled or pickled surface, cheaper, looser diameter, the right choice when you will machine the skin off.
- Cold drawn or precision drawn — tighter diameter, brighter surface, better for a pin that has to fit a reamed hole.
- Centreless ground — a shaft finish. You pay for straightness and a diameter you can measure twice.
None of those is a polished tube. None of them is flat bar. A 20 mm “stainless rod” on a hardware aisle is not a mill bar with a heat number.
Australian counters typically stock 304/304L and 316/316L in a ladder of millimetre diameters: 6, 8, 10, 12, 16, 20, 25, 32, 40, 50 mm and then the heavier shafts. Odd imperial leftovers (½ inch, ¾ inch) still turn up on imported drawings. Convert them on the purchase order. Do not hope the sawyer will.
| Duty | Typical grade | Typical product | Why |
|---|---|---|---|
| Indoor pin, hinge, cabinet hardware | 304 / 304L | Drawn round | Enough corrosion resistance, easy to machine |
| Coastal or pool hardware | 316 / 316L | Drawn or ground | Molybdenum for chlorides |
| Heavy machining, no weld | 303 | Drawn | Sulphur helps the tool; welding suffers |
| Strength plus chloride | Duplex 2205 | Bar from a specialist | Not a hardware-aisle item |
The grade decision is the same family argument as 304 versus 316 in Australia. Bar does not get a free pass because it is “only a pin.” A 304 pin in a 316 coastal rail is a couple waiting to stain.
Cut length, tolerance and the saw
Custom-cut bar is a length and a square end, not a machined face. A bandsaw or cold saw leaves a burr. A lathe faces the end. Say which you want.
The historic Melbourne custom-cut shop advertised a grown-up tolerance on sheet — about ±2 mm. Bar cut on a trade saw is in the same honest band unless you pay for a machined length. If the pin has to be 139.5 mm between shoulders, that is a turning job, not a saw booking.
Write the order as:
“316L stainless solid round, 20 mm drawn, cut 6 lengths at 1400 mm, mill certificate, ends as-sawn, deburr.”
If you need a thread, say the standard: metric coarse is the Australian default (M10, M12, M16). UNC leftovers belong on an imported machine. A2 versus A4 fasteners is the bolt version of the same alloy story; a threaded bar is not a certified bolt just because someone ran a die down it.
Machining and welding habits that matter
Austenitic bar work-hardens. A timid drill and a blunt tool will glaze the hole and then break. Use sharp tooling, a firm feed, and a coolant that is not a chloride surprise. 303 exists because production shops got tired of 304 grabbing a tap. That is a real reason to buy 303. It is not a reason to weld 303 into a 316 balustrade and then wonder why the joint is ugly.
If you will TIG the bar — a shaft boss, a welded pin, a lug — specify 304L or 316L and treat the joint like any other austenitic weld: matching filler, back-purge where the drawing asks, pickle the tint, passivate after fabrication. Welding 304 and 316 stainless is the procedure essay. Bar does not change the metallurgy.
Heat tint on a small diameter looks worse than on sheet because there is less mass to soak the heat. A short pin welded with a fat TIG puddle will show a rainbow that becomes a brown ring outdoors. That is not “cheap bar.” That is an uncleaned weld.
When bar is the wrong section
A handrail in solid 25 mm rod is a gym weight. Australian balustrades are almost always tube, because stiffness per kilogram and a place to hide a weld both matter. Solid bar wins when you need:
- a shaft that will be turned
- a pin that cannot crush
- a threaded stud
- a machine part with a hole through the centre you will bore yourself
Solid bar loses when you need a light rail, a folded tray, or a decorative post. The old catalogue kept bar, tube and sheet in separate aisles for a reason.
Do not substitute flat bar for round because the merchant is out of 16 mm. A flat strap and a round pin do different jobs. Do not substitute a folded angle for a turned boss.
Finish, marking and the certificate
HRAP bar looks dull. Clients who were promised “stainless” in the kitchen sense will call it dirty. Show a sample. Drawn bar looks brighter and still is not a No. 4 sheet. If the pin is visible on a coastal job, say whether it will be polished, bead-blasted, or left as-drawn. Polishing a bar after threading wrecks the thread. Sequence the work.
Stamp or engrave the grade if the part will live in a bag of mixed offcuts. How to identify a stainless steel grade is what happens when nobody stamped the leftover. A magnet still will not separate 304 from 316.
Ask for the mill certificate. Heat number on the docket, not “it’s 316, mate.” The historic Alltrade counters at least named the three grades they stocked. Keep that habit for bar. If the duty is seawater or a loaded shaft, you may already be in duplex versus 316 territory — and that bar will not be on a walk-in rack next to the 20 mm 304.
A short Australian order you can copy
Indoor café hardware: “304L drawn round, 12 mm, cut 20 lengths at 85 mm, as-sawn, mill cert, no thread.”
Coastal gate pin: “316L drawn round, 16 mm, cut 4 lengths at 220 mm, face one end, M12 thread 40 mm, mill cert, passivate after threading.”
Machine shop blank: “303 drawn round, 25 mm, 3 m lengths, certificate, no weld.”
If the part has to become a tray, a lid or a channel, you are in the custom-cut and sections hub, not in the bar rack. If it has to live beside a pool, read pool and marine stainless fittings before you pick 304 because it was in the truck.
Bar is boring until it is wrong. Write the diameter in millimetres, the alloy with an L if you will weld, the product form, and the certificate. That is the whole skill.