316 Stainless Steel Rod and Flat Bar

316 stainless steel rod is the molybdenum-bearing austenitic bar specified wherever chlorides reach the part: marine fittings, chemical plant, food and pharmaceutical equipment, and coastal architectural hardware. Its 2 to 3 percent molybdenum lifts the pitting resistance equivalent number to about 25 against 19 for 304, and the low-carbon 316L version welds without sensitising. Walmay supplies round bar from 3 mm to 300 mm diameter, along with flat, square and hex sections, to ASTM A276 and EN 10088-3, cut to length with an EN 10204 3.1 certificate.

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  • Excellent Corrosion Resistance

    Molybdenum-alloyed to prevent pitting in high-salinity waters. Outlasts standard 304 by 3x in coastal applications, significantly reducing maintenance downtime.

  • Solid & Tough, Highly Machinable

    Optimized for CNC. Low material loss (≤2%) improves your production efficiency by 30% compared to carbon steel, saving on total project costs.

  • Quick Stock Supply

    Over 300 tons of stock (Φ5–200mm) ready for 24-hour dispatch. We ensure your production line stays moving without supply delays.

Product Specifications

Round Bar Sizes and Weight

Weight per metre equals diameter squared in millimetres multiplied by 0.00623 for austenitic grades.

DiameterWeight per metreWeight per 3 m bar
5 mm0.16 kg0.5 kg
6 mm0.22 kg0.7 kg
8 mm0.40 kg1.2 kg
10 mm0.62 kg1.9 kg
12 mm0.90 kg2.7 kg
16 mm1.59 kg4.8 kg
20 mm2.49 kg7.5 kg
25 mm3.89 kg11.7 kg
30 mm5.61 kg16.8 kg
40 mm9.97 kg29.9 kg
50 mm15.58 kg46.7 kg
60 mm22.43 kg67.3 kg
80 mm39.87 kg119.6 kg
100 mm62.30 kg186.9 kg
150 mm140.18 kg420.5 kg
200 mm249.20 kg747.6 kg
250 mm389.38 kg1,168.1 kg
300 mm560.70 kg1,682.1 kg

Imperial diameters from 1/8 inch to 10 inch are also stocked. Bars up to about 25 mm are supplied cold drawn or peeled and polished; above that they are hot rolled, and above about 100 mm they are forged and rough turned.

Specification
ItemDetail
Grade316, UNS S31600, and 316L, UNS S31603, EN 1.4401 and 1.4404
StandardsASTM A276, ASTM A479 for pressure vessel parts, ASTM A582 for free machining, EN 10088-3
Round bar range3-300 mm diameter
Other sectionsFlat, square, hexagon, angle
Length3 m, 6 m, or cut to length plus or minus 1 mm
ConditionSolution annealed, cold drawn, peeled, or centreless ground
SurfacePickled, bright drawn, ground to h9 or h11, polished
PRENAbout 25
CertificationEN 10204 3.1, PMI and NDT on request
Chemical Composition
Element316316L
Carbon0.08 max0.030 max
Chromium16.0-18.016.0-18.0
Nickel10.0-14.010.0-14.0
Molybdenum2.00-3.002.00-3.00
Manganese2.00 max2.00 max
Silicon1.00 max1.00 max
Phosphorus0.045 max0.045 max
Sulphur0.030 max0.030 max
Mechanical Properties
Property316 annealed316L annealed316 cold drawn
Yield strength205 MPa min170 MPa min400-700 MPa
Tensile strength515 MPa min485 MPa min700-900 MPa
Elongation40 percent40 percent12-25 percent
Hardness95 HRB max95 HRB max25-35 HRC
Density8.0 g/cm38.0 g/cm38.0 g/cm3

Cold drawing raises the strength substantially, which is worth remembering when a drawing quotes a minimum yield well above 205 MPa: it may be achievable in cold-drawn bar without changing grade. Ask for the tested values on the certificate rather than assuming annealed minimums.

316 Stainless Steel Flat Bar and Other Sections
SectionRangeTypical use
Flat bar10x3 mm to 200x50 mmBrackets, base plates, chainplates, trim
Square bar6x6 mm to 100x100 mmMachined blanks, frames, decorative posts
Hexagon bar6 mm to 75 mm across flatsFasteners, fittings, machined parts held in a chuck
Angle20x20x3 mm to 100x100x10 mmFrames, supports, edge protection
Round bar3-300 mmShafts, pins, fasteners, machined components

The full size range, hot rolled and cold drawn tolerances and bending guidance for rectangular sections are on our flat bar page. Square and hex sections in this grade are covered on the square bar and hex bar pages.

Where 316 Reaches Its Limit
Service316 / 316LBetter choice
Coastal atmosphereCorrect-
Splash zone and deck fittingsCorrect-
Continuous seawater immersionPits and suffers crevice corrosion2507 super duplex or 6Mo
Warm chlorinated water, pool fixingsNot for load-bearing fixings2205 duplex or a 6Mo grade
Sulphuric or phosphoric acidNo904L
Above 870 CScales310S
High strength shaftsMarginal, 205 MPa yield630 / 17-4 PH or 2205
Wear surfacesPoor, galls readily420 or 410 hardened

The pool hall case is worth naming, because it has caused structural failures. Load-bearing 316 fixings in the warm chlorinated atmosphere above a pool are vulnerable to chloride stress corrosion cracking, which gives no visible warning before fracture. Standards for that environment now call for higher grades.

Ordering
ItemDetail
Minimum order500 kg from stock, 2 tonnes for mill sizes
Lead time from stock7-12 days
Lead time mill run30-50 days
Stock range6-100 mm round in 316 and 316L, plus flat and square sections
DocumentationEN 10204 3.1 with analysis and mechanical results, PMI on request
PackingBundled and strapped, tubes or crates for small diameters
IncotermsFOB, CIF, DAP

Send the section and size, grade, condition, length or cut list, and any tolerance or surface requirement. Related products: flat bar, 304 round bar, square bar, hex bar, 303 free machining bar, and the full bar and rod range.

Pricing Calculation

Workshop & Manufacturing Machine

Stainless Steel Plate Bending/Stamping Process

Stainless Steel Plates on Storage Rack

Palletized Stainless Steel Plates

Stainless Steel Plate Rolling Line

Precision Thickness Inspection of Stainless Steel Plate

Forklift Loading Stainless Steel Plates for Shipment

Round, square and hex stainless steel bars bundled on a mill storage rack
Close-up of a stainless steel bar end face showing the hexagonal cross-section and machined finish

316 stainless steel rod is the molybdenum-bearing austenitic bar specified wherever chlorides reach the part: marine fittings, chemical plant, food and pharmaceutical equipment, and coastal architectural hardware. Its 2 to 3 percent molybdenum lifts the pitting resistance equivalent number to about 25 against 19 for 304, and the low-carbon 316L version welds without sensitising. Walmay supplies round bar from 3 mm to 300 mm diameter, along with flat, square and hex sections, to ASTM A276 and EN 10088-3, cut to length with an EN 10204 3.1 certificate.

Machining

316 machines like 304, which is to say poorly compared with carbon steel, and for the same reasons: it work hardens ahead of the tool, its chips are gummy and long, and its low thermal conductivity concentrates heat at the cutting edge.

ParameterPractice
Cutting speed20 to 30 percent below carbon steel
FeedPositive and constant, never dwell in the cut
Depth of cutDeep enough to cut below the work-hardened layer left by the previous pass
ToolingSharp carbide, positive rake, generous chip clearance
CoolantFlood, high volume, to carry heat away from the edge
RigidityMaximum, since chatter work hardens the surface immediately

Where machining is the dominant cost and the corrosive service is mild, 303 is the free-machining austenitic grade, with sulphur added to break chips. It should not be substituted where corrosion matters, because those sulphide inclusions are pitting initiation sites. Our bar and rod machining guide covers the trade-offs in more detail.

Bundled stainless steel bars strapped and tagged for shipment on a warehouse pallet

Applications

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FAQs

What are the disadvantages of 316 stainless steel?
It costs 25 to 40 percent more than 304 and is exposed to both nickel and molybdenum surcharges. Its yield strength of 205 MPa is modest for a structural or shaft material, so sections are heavier than duplex or precipitation hardening alternatives. It machines poorly, work hardening ahead of the tool and producing gummy chips. It galls against itself, which is why 316 threads seize without an anti-seize compound. And it is not immune to chlorides: in seawater immersion, in crevices, or in warm chlorinated air it will pit or crack.
Will 316 stainless eventually rust?
It can, under specific conditions. In continuous seawater immersion it will pit over time; under gaskets, washers and bolted joints crevice corrosion concentrates chloride and attacks the metal; and free iron transferred from carbon steel tooling rusts on the surface and looks like grade failure. In ordinary coastal atmosphere, rinsed by rain and properly passivated, 316 stays clean for decades. The measures that matter are eliminating crevices in the design, using stainless-only tooling, and passivating after machining.
Is stainless steel 304 or 316 better?
For chloride environments, 316, because its 2 to 3 percent molybdenum raises pitting resistance from about 19 to about 25. For anything indoors, inland, or in fresh water, 304 performs identically and costs 25 to 40 percent less. Their strength is the same, so there is no mechanical reason to prefer either. As bar specifically, both machine and weld similarly, so the decision reduces to whether salt, brine or aggressive cleaning chemicals will reach the part.
What is the strongest stainless steel rod?
Among readily available grades, precipitation hardening 17-4 PH, UNS S17400 and grade 630, reaches roughly 1,000 to 1,300 MPa yield strength after ageing while retaining corrosion resistance close to 304, which makes it the usual answer for high-strength shafts. Martensitic 420 hardens to 55 HRC for wear resistance but is brittle and corrodes more readily. 2205 duplex offers 450 MPa yield with better corrosion resistance than 316. Cold-drawn 316 itself reaches 400 to 700 MPa, well above the annealed minimum, which is often enough without changing grade.
Should I order 316 or 316L bar?
316L where the bar will be welded and cannot be solution annealed afterwards, since its 0.030 percent carbon ceiling prevents sensitisation. 316 where you want the extra 35 MPa of yield strength and the part is machined rather than welded. Much of our stock is dual certified to both, which resolves the question and costs the same. For heavily loaded machined parts, ask for the tested mechanical values, since cold-drawn bar typically well exceeds either minimum.
What diameter tolerance can you hold?
Cold drawn bar to h11, roughly minus 0.11 mm on a 25 mm diameter. Peeled and polished bar to h10 or h11 depending on size. Centreless ground bar to h9, about minus 0.052 mm on 25 mm, and tighter by agreement. Hot rolled bar above about 25 mm carries a rolled tolerance of plus or minus 0.5 to 1.5 mm depending on diameter, so any part needing a fit should be ordered ground or machined from oversize.
Why do 316 threads seize, and what prevents it?
Austenitic stainless steels gall: two identical passive surfaces under pressure tear their oxide films and cold weld together, which locks the thread. It is a property of the material, not a fault in the fastener. Prevention is straightforward: use an anti-seize compound on assembly, avoid running fasteners down at speed, and where the joint will be repeatedly dismantled, pair a 316 fastener with a different grade or use a coated nut.