Alloy Steel EN31 Round Bar
➡️ UNS G52986 | EN 1.3505 | 100Cr6 | AISI 52100 | ASTM A295
➡️ ASTM, EN, JIS & International Standards
➡️ Supply Conditions
➡️ Multiple Diameters & Supply Lengths
➡️ Global Export & International Delivery
Country of Origin:
Europe, Japan, USA
Material Type:
Alloy Steel
UNS Number:
G52986
Wr. No.:
1.3505
MTC Available:
EN 10204 3.1
Product Description for Alloy Steel EN31 Round Bar
Alloy Steel EN31 Round Bar is a high-carbon chromium bearing steel known in the British system as EN31 and in BS 970 as 535A99. It contains about 0.95–1.10% carbon and 1.20–1.60% chromium. Its nearest international grades are 100Cr6 (1.3505) and AISI 52100.
After hardening and low-temperature tempering, EN31 reaches very high hardness and excellent wear resistance. It also has high compressive strength and good fatigue resistance, which are essential for rolling contact parts such as bearings.
The steel is normally supplied spheroidise annealed so that it can be machined. After machining, parts are hardened by oil quenching from about 810–850°C and tempered at about 150–200°C.
Bars are supplied hot rolled, forged, peeled, turned or ground.
Common applications include ball and roller bearings, bearing races, rollers, spindles, cams, gauges, punches, dies, press tools and other wear parts. It is widely used in India and the UK under the EN31 name. Where rolling bearings are critical, buyers often specify 100Cr6 to EN ISO 683-17 with defined cleanliness. Outside bearings, EN31 is popular in tool rooms and general engineering because it is cheap, easy to buy and reaches very high hardness with a simple oil quench. It is used for press tools, punches, gauges, mandrels, rollers and cams. For high-duty rolling bearings, most buyers now order 100Cr6 to EN ISO 683-17, which adds cleanliness and structure limits that the old BS 970 grade did not cover. Ground bars are stocked for precision work, and peeled bars are used where parts are rough turned before hardening, so the decarburised skin is fully removed.
Common Applications of Alloy Steel EN31 Round Bar
➡️ Machined shafts, spindles, valve stems, pump sleeves and pins for food, beverage, dairy and pharmaceutical equipment, where the passive chromium oxide film resists both product acids and caustic clean-in-place chemicals.
➡️ Fasteners, studs, bolts, threaded rod and anchor components produced from bar stock, chosen for corrosion resistance combined with the ductility needed for cold heading and thread rolling.
➡️ Chemical, water treatment and general process plant parts such as agitator shafts, flange blanks, nozzles and support components handling water, steam and mildly corrosive media free of significant chlorides.
➡️ Architectural and structural hardware including handrail stanchions, balustrade fittings, tension rods and bollards, where a bright ground or polished bar finish provides both appearance and low maintenance.
International Equivalent Grade for EN31 Round Bar
Standard
Country / Region
Grade
UNS
USA
UNS G52986 / J19965
AISI/SAE
USA
52100 / E52100
EN
Europe
EN 1.3505
JIS
Japan
SUJ2
KS
South Korea
STB2 / STS3
GB
China
GCr15
BS
UK
535A99 / 534A99
DIN
Germany
100Cr6
AFNOR
France
100C6
GOST
Russia
ShKh15 (ШХ15)
ISO
International
100Cr6
Technical Specification for Alloy Steel EN31 Round Bar
Specification
Value
Unit
Material
Alloy steel
-
Grade
EN31 / 535A99
-
Standard
BS 970-2 (535A99), nearest EN ISO 683-17 100Cr6
-
Product Form
Round bar (hot rolled, forged or bright)
-
Diameter (supply range)
10–400
mm
Length (random)
3–6
m
Manufacturing Process
Hot rolled or forged, optional peeling, turning, cold drawing or grinding
-
Production Route
EAF or BOF + ladle refining + vacuum degassing
-
Surface Finish
Black, shot blasted, peeled, turned, cold drawn or ground
-
Heat Treatment / Delivery Condition
Spheroidise annealed
-
Tolerance Standard
EN 10060 (hot rolled), EN 10278 (bright, h9-h11), or as agreed
-
Carbon Equivalent CEV (IIW, calculated from mid-range analysis)
≈ 1.4
-
Density
7.85
g/cm³
Thermal Conductivity at 20°C
42
W/m·K
Coefficient of Thermal Expansion 20–100°C
11.5
µm/m·K
Specific Heat at 20°C
460
J/kg·K
Modulus of Elasticity at 20°C
210
GPa
Magnetic Properties
Ferromagnetic
-
Testing / Inspection
Chemical analysis, hardness, tensile and impact where specified, UT (EN 10308 / SEP 1921 / ASTM A388), grain size, Jominy on request
-
Certification
EN 10204 3.1 mill test certificate (3.2 on request)
-
Technical Specifications
Get the key technical specifications for Alloy Steel EN31 Round Bar
EN31 Round Bar is ordered to BS 970 as 535A99. As BS 970 is withdrawn, many buyers now order 100Cr6 to EN ISO 683-17 or 52100 to ASTM A295 for bearing use.
Bars are supplied spheroidise annealed for machinability. Hardening is by oil quenching from about 810–850°C, followed by tempering at about 150–200°C.
For bearing parts, cleanliness, decarburisation limits and microstructure are important and should be specified.
Welding is not recommended because of the very high carbon content.
Spheroidise annealed bar has a structure of fine, round carbides in soft ferrite. This structure is needed for good machining and for a uniform response to hardening. The order should state the maximum annealed hardness and, for bearing work, the required carbide structure, decarburisation depth and inclusion rating. Ground or peeled bar is preferred for parts that will be machined with little stock allowance, because hot rolled bar has a decarburised skin that will be soft after hardening. Parts should be hardened soon after rough machining and ground to size after tempering.
Welding is not recommended because of the very high carbon.
Chemical Composition for Alloy Steel EN31 Round Bar
Element
Symbol
Min
Max
Unit
Carbon
C
0.95
1.10
%
Silicon
Si
0.10
0.35
%
Manganese
Mn
0.40
0.70
%
Chromium
Cr
1.20
1.60
%
Chemical Composition
View the chemical composition and applicable material limits for EN31 Round Bar
The table shows the principal BS 970 limits for 535A99 (EN31). Phosphorus, sulfur and residual limits should be taken from the ordered standard.
Carbon at 0.95–1.10% gives very high hardness after quenching and forms hard carbides that resist wear.
Chromium at 1.20–1.60% raises hardenability and forms chromium carbides that improve wear resistance.
Manganese adds hardenability, and silicon acts as a deoxidiser. The composition of EN31 differs slightly from 100Cr6 and 52100. EN31 allows carbon up to 1.10% and manganese of 0.40–0.70%, while 100Cr6 has carbon of 0.93–1.05%, chromium of 1.35–1.60% and manganese of 0.25–0.45%. These differences are small for tool and wear parts, but bearing makers usually require the modern standards. At about 1% carbon, much of the carbon forms hard chromium-iron carbides, which give wear resistance. After hardening, the rest of the carbon goes into martensite, giving a very hard matrix. Low sulfur and oxygen reduce the inclusions that can start rolling contact fatigue cracks.
Silicon at 0.10–0.35% deoxidises the steel and adds a little resistance to softening during tempering. Phosphorus and sulfur should be low, because they reduce toughness and can start fatigue cracks in rolling contact parts.
Mechanical Properties for Alloy Steel EN31 Round Bar
Mechanical Property
Value
Unit
Hardness (spheroidise annealed)
≤ 229
HB
Hardness (hardened and low-temperature tempered)
60–65
HRC
Tensile Strength (annealed)
750
MPa
Mechanical Properties
Check the key mechanical properties and performance requirements of EN31 Round Bar
The values shown are reference hardness and strength levels for EN31 and are for guidance only.
In the annealed condition, the steel is soft enough to machine. After hardening and tempering, it reaches about 60–65 HRC, which gives excellent wear and rolling contact fatigue resistance.
Confirm the delivery hardness and heat treatment response on the mill certificate. BS 970 does not set tensile requirements for EN31, so the table values are guidance figures. The important checks are the annealed hardness for machining, about 229 HB maximum, and the hardness after heat treatment, about 60–65 HRC. Tempering at about 150–200°C keeps hardness high while reducing brittleness. Retained austenite can cause size changes over time, so precision gauges and bearings may need sub-zero treatment before tempering. Because EN31 is very hard and has low toughness after hardening, parts should not be used for shock-loaded structural parts.
Compressive strength after hardening is very high, which is why EN31 works well for punches and rolls. Bearing-grade parts are also checked for microstructure and retained austenite after heat treatment, and gauges are often stabilised to keep their size over years of use.
Dimension / Sizes for Alloy Steel EN31 Round Bar
Dimension / Size
Value
Unit
Available Diameter Range (supply capability)
10–400
mm
Standard Length (random)
3–6
m
Custom / Cut-to-Length
Available on request
-
Diameter Tolerance
EN 10060 (hot rolled), EN 10278 (bright, h9-h11), or as agreed
-
Length Tolerance
Per ordered standard or as agreed (commonly +50 / -0 mm for cut lengths)
-
Straightness Tolerance
Per EN 10060 / EN 10278 or as agreed
-
End Condition
Saw cut square, chamfered or as ordered
-
Surface Finish
Black (as rolled or forged), shot blasted, peeled, rough turned, cold drawn, centreless ground
-
Dimensions & Sizes
Explore available diameters, lengths, and dimensional requirements for EN31 Round Bar
Pricing for Alloy Steel EN31 Round Bar
Round Bar Prices are generally quoted per kilograms or meters tonnes and can fluctuate with the global raw material and market prices. The final price will depend on a variety of factors, including the grade size, diameter, length, surface finish, the quantity and whether the bars are cut to length or in standard lengths.
For smaller quantities, we can also quote per metre or per piece basis once the required dimensions have been confirmed. Container-loads or orders that are larger in size are typically priced per tonne, based upon the specifications required and the supply conditions.
Please provide your desired dimensions, grades, length number, and end for a current quote including the lead time applicable and details for certification.
Pricing
Get current Alloy Steel EN31 Round Bar pricing based on size, quantity, grade, finish, and delivery requirements.
Why Choose Us
Euro Steel Bars is an international distributor, stockist and exporter of stainless round steel bars that cover carbon, stainless alloy, special grades. We stock a variety of sizes and grades. We guarantee every order with mill test certificates as well as full quality-assurance documentation. Our name speaks to our roots: European-sourced materials that is backed by the certificates and rigor that buyers from Asia as well as the Gulf and Africa are looking for.
Each bar we deliver is accompanied by EN 10204 3.1 mill test certificates as well as complete documentation of quality, so what you receive corresponds to what’s written in the documents. We carry a selection of sizes and grades ready for transport, and cut length upon the request of customers, which results in quicker lead times, whether you’re ordering just a one-off spec or a complete project tonnage.
We operate an actual wholesale business that is that is supported with an internationally-operated supply chain therefore we are able to serve fabricators sourcing one grade the same way in the same way as an EPC contractor who is placing a large order. Our clients include manufacturers, fabricators EPC construction companies, engineers oil and gas projects as well as construction companies. we design our inventory as well as documentation to show what buyers need to bring projects forward.
Our customers trust us across Qatar, Oman, Bahrain, Kuwait, Jordan, Malaysia, Singapore, Thailand, Taiwan, Turkey, Italy and South Africa. If you’re looking to source an Gulf energy project, or a construction project within Southeast Asia, you get the same quality of certified material, the exact documentation, and the exact delivery procedure.
Frequently Asked Questions
Should I choose EN31 or EN24?
Is EN31 the same as 100Cr6 and AISI 52100?
What hardness can EN31 reach?
Can EN31 be welded?
How is EN31 heat treated and machined?
What are the limits of EN31?
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