Alloy Steel B16 Round Bar
➡️ B16 | UNS K14072 | ASTM A193 Grade B16
➡️ 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:
K14072
Wr. No.:
-
MTC Available:
EN 10204 3.1
Product Description for Alloy Steel B16 Round Bar
B16 is the ASTM A193 grade designation for quenched and tempered chromium-molybdenum-vanadium bolting steel, UNS K14072. Bar ships to ASTM A193 / A193M with dimensions to ASTM A29 / A29M.
It exists to solve the problem B7 cannot. B7 is limited to roughly 425 C because it continues to temper in service above that, losing bolt preload through stress relaxation. B16 adds 0.25-0.35% vanadium and is tempered at 649 C minimum, which produces fine vanadium carbides that resist coarsening. The result is a bolting material that holds preload to around 540 C.
Composition is otherwise similar to B7, with carbon at 0.36-0.47%, chromium at 0.80-1.15% and molybdenum raised to 0.50-0.65%.
Strength requirements are banded by diameter as with all quenched and tempered bolting. Up to 64 mm the requirement is 860 MPa minimum tensile plus 725 MPa minimum proof strength, with reduced values in larger sections.
Aluminium is capped at 0.015%, which is easy to overlook. Aluminium interferes with the vanadium carbide chemistry that provides the temperature capability, so the limit protects the very property the grade is bought for.
Note also that ASTM A320 lists a separate Grade B16 covering low-temperature bolting service, so the correct standard should be named on the order to avoid receiving material heat treated for a different purpose.
Diameters run 6 mm to 180 mm, as random lengths or cut to size. The steel is ferromagnetic and is not weldable in any practical sense, so studs and fasteners are machined and threaded from bar.
Typical work is high-temperature flange bolting, steam and turbine fasteners, and hot pressure-vessel studs.
Common Applications of Alloy Steel B16 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 Alloy Steel B16 Round Bar
Standard
Country / Region
Grade
ASTM A193 / A193M
USA
Grade B16 (UNS K14072)
ASTM A320 / A320M
USA
Grade B16 (where low-temperature service applies)
Technical Specification for Alloy Steel B16 Round Bar
Specification
Value
Unit
Material
Alloy steel
-
Grade
B16 / UNS K14072
-
Product Form
Round bar / rod for bolting
-
Standard
ASTM A193 / A193M Grade B16
-
Diameter
6 - 180 (typical supply range)
mm
Length
3 - 6 (random), or cut to length
m
Manufacturing Process
Hot rolled or forged, quenched and tempered
-
Production Route
EAF or BOF with ladle refining, continuous cast or ingot
-
Surface Finish
Hot-rolled, rough-turned, peeled, smooth-turned, centreless ground
-
Heat Treatment / Delivery Condition
Quenched and tempered at 649 C minimum
-
Tolerance Standard
ASTM A29 / A29M
-
Density
7.85 (typical)
g/cm3
Melting Range
1425 - 1510 (typical)
C
Thermal Conductivity at 100 C
42.0 (typical)
W/m.K
Coefficient of Thermal Expansion (20-100 C)
12.5 (typical)
um/m.C
Specific Heat (0-100 C)
460 (typical)
J/kg.K
Electrical Resistivity at 20 C
0.22 (typical)
uOhm.m
Modulus of Elasticity at 20 C
205 (typical)
GPa
Magnetic Properties
Ferromagnetic in all conditions
-
Service Temperature Range
-30 to 593 per ASTM A193, typical practical limit around 540
C
Testing / Inspection Standard
ASTM A370 for mechanical testing, ASTM A193 for hardness verification
-
Certification / Inspection Documents
EN 10204 3.1 or 3.2 mill test certificate
-
Technical Specifications
Get the key technical specifications for Alloy Steel B16 Round Bar
Supply runs to ASTM A193 / A193M as Grade B16, with dimensional tolerance, straightness and surface condition from ASTM A29 / A29M.
The delivery condition is quenched and tempered at 649 C minimum, which is 56 C higher than the 593 C required for B7. That higher tempering temperature is what makes the grade stable in hotter service, because a bolt only stays dimensionally and metallurgically stable at temperatures below the one at which it was tempered.
Strength requirements are banded by diameter, for the same hardenability reason that applies to B7. Up to 64 mm the requirement is 860 MPa minimum tensile plus 725 MPa minimum proof strength, with reduced figures in larger sections. Bolt design has to use the values for the actual diameter rather than the headline number.
Two points are commonly missed at order stage. The aluminium cap of 0.015% protects the vanadium carbide chemistry that provides the temperature capability, and a heat with high aluminium can meet every other requirement while underperforming in stress relaxation. And ASTM A320 also lists a Grade B16 for low-temperature bolting service, so the correct standard should be named.
The grade is not weldable in any practical sense. Fasteners are machined and threaded from bar.
Chemical Composition for Alloy Steel B16 Round Bar
Element
Symbol
Min
Max
Unit
Carbon
C
0.36
0.47
%
Manganese
Mn
0.45
0.70
%
Silicon
Si
0.15
0.35
%
Phosphorus
P
-
0.035
%
Sulfur
S
-
0.040
%
Chromium
Cr
0.80
1.15
%
Molybdenum
Mo
0.50
0.65
%
Vanadium
V
0.25
0.35
%
Aluminium
Al
-
0.015
%
Iron
Fe
Balance
-
%
Chemical Composition
View the chemical composition and applicable material limits for Alloy Steel B16 Round Bar
Vanadium at 0.25-0.35% is the addition that defines the grade. It forms fine vanadium carbides that resist coarsening at temperature far better than the chromium and iron carbides in B7, and that stability is what allows the bolt to hold its preload at temperatures where B7 would relax and the joint would loosen.
Molybdenum at 0.50-0.65% is roughly double the B7 level. It adds hardenability, strengthens the solid solution, and importantly reduces susceptibility to temper embrittlement, which matters for a material tempered at 649 C and used for long periods at elevated temperature.
Carbon at 0.36-0.47% provides the martensitic strength on quenching, and chromium at 0.80-1.15% supplies hardenability so that martensite forms through the section rather than just at the surface.
Aluminium capped at 0.015% is the limit most often overlooked. Aluminium interferes with the carbide and nitride chemistry that the vanadium addition relies on, and a heat running high in aluminium can satisfy every other composition and mechanical requirement while quietly failing to deliver the stress relaxation resistance the grade exists to provide.
Manganese at 0.45-0.70% and silicon at 0.15-0.35% deoxidise and add hardenability. Phosphorus and sulphur are residual limits.
Mechanical Properties for Alloy Steel B16 Round Bar
Mechanical Property
Value
Unit
Tensile Strength, M64 and under
860
MPa (minimum)
Yield Strength 0.2% Proof, M64 and under
725
MPa (minimum)
Elongation in 4D, M64 and under
18
% (minimum)
Reduction of Area, M64 and under
50
% (minimum)
Tensile Strength, over M64 to M100
760
MPa (minimum)
Yield Strength 0.2% Proof, over M64 to M100
655
MPa (minimum)
Elongation in 4D, over M64 to M100
17
% (minimum)
Reduction of Area, over M64 to M100
45
% (minimum)
Tensile Strength, over M100 to M180
690
MPa (minimum)
Yield Strength 0.2% Proof, over M100 to M180
585
MPa (minimum)
Elongation in 4D, over M100 to M180
16
% (minimum)
Reduction of Area, over M100 to M180
45
% (minimum)
Hardness, all diameters
321
HBW (maximum)
Hardness, all diameters
35
HRC (maximum)
Modulus of Elasticity
205
GPa (typical)
Mechanical Properties
Check the key mechanical properties and performance requirements of Alloy Steel B16 Round Bar
These come from ASTM A193 / A193M for Grade B16, tested to ASTM A370. Strength figures are minima and hardness is a maximum. As with all quenched and tempered bolting, requirements are banded by diameter, and ASTM A193 sets three bands. Up to M64 the requirement is 860 MPa tensile and 725 MPa proof strength with 18% elongation and 50% reduction of area. Over M64 to M100 it falls to 760 and 655 MPa with 17% and 45%. Over M100 to M180 it falls again to 690 and 585 MPa with 16% and 45%. Hardness is capped at 321 HBW or 35 HRC across all three.
Up to 64 mm the requirement is 860 MPa minimum tensile plus 725 MPa minimum proof strength, with 18% minimum elongation and 50% minimum reduction of area. Note that the elongation requirement is higher than B7 at the same size, reflecting the tougher condition produced by the higher tempering temperature.
Room-temperature strength is essentially the same as B7. That is not where the difference lies. What separates B16 is stress relaxation behaviour at temperature, which no room-temperature test measures. A B7 bolt at 500 C will progressively shed preload as the microstructure continues to temper, while a B16 bolt holds it because the vanadium carbides remain stable.
For hot bolting design, stress relaxation data at the service temperature is the relevant basis, not the tensile figures.
Dimension / Sizes for Alloy Steel B16 Round Bar
Dimension / Size
Value
Unit
Diameter
6 - 180
mm
Standard Length
3 - 6 (random / mill lengths)
m
Custom Length
Cut to length available on request
-
Diameter Tolerance
Per ASTM A29 / A29M, varies with size and finish
-
Length Tolerance
Per ASTM A29 / A29M or as agreed at order
-
Straightness Tolerance
Per ASTM A29 / A29M or as agreed at order
-
End Condition
Square cut, chamfered, or as ordered
-
Surface Finish
Hot-rolled, rough-turned, peeled, smooth-turned, centreless ground
-
Available Size Range
6 - 180, larger diameters subject to enquiry
mm
Cut-to-Length Availability
Available
-
Dimensional Standard
ASTM A29 / A29M
-
Dimensions & Sizes
Explore available diameters, lengths, and dimensional requirements for Alloy Steel B16 Round Bar
Pricing for Alloy Steel B16 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 B16 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
What is Alloy Steel B16 Round Bar?
What is the difference between B7 and B16?
What is stress relaxation and why does it matter for bolting?
What standard does Alloy Steel B16 Round Bar comply with?
What are the key mechanical properties of Alloy Steel B16 Round Bar?
Why is aluminium limited to 0.015% in B16?
Are there equivalent grades for B16 in other standards?
Can Alloy Steel B16 Round Bar be welded?
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