ISO 9001:2015 Certified EN 10204 3.1 Traceability NACE MR0175 / ISO 15156 EIL & IBR Approved
Rajtilak Metal is an Indian manufacturer and international exporter of high tensile ASTM A193 Grade B6 Bolts, fully threaded stud bolts, heavy hex nuts, socket head cap screws, and threaded bars in martensitic stainless steel (AISI 410 / UNS S41000).
Manufactured strictly according to ASME B18.2.1, ASME B18.2.2, ASME B18.3, and DIN standards, ASTM A193 Grade B6 fasteners are engineered with a nominal 13% chromium composition. Quenched and tempered at a minimum of 1100°F (593°C), they deliver a minimum tensile strength of 110 ksi (760 MPa) and a yield strength of 85 ksi (585 MPa), providing outstanding mechanical stability and moderate oxidation resistance in steam turbines, pressure vessels, high-pressure valves, and refinery heater connections.
Grade B6 Hex Head Bolts
SA 193 B6 Stud Bolts
AISI 410 Hex Nuts
A193 B6 Threaded Rod
Engineering Specification Index
Technical Specification Scope
Chemical Composition Limits
Mechanical & Hardness Properties
ASME SA 193 B6 Hex Bolt Dimensions
A193 B6 Hex Nuts Dimensions
ASTM A193 B6 Stud Bolts Dimensions
Socket Head Cap Screw Dimensions
Threaded Rod Metric & Imperial Sizes
Flat Washer Dimension Standards
Nut Sizing & Height Reference
DIN 975 Grade B6 Yield Strength
A193 Grade B6 Torque Values
Physical Properties Matrix
DIN to ISO Conversion Standard
Heat Treatment & Marking Codes
Manufacturing Scope
ASTM A193 Grade B6 Fasteners Specification Matrix
| Parameter | Standard Manufacturing Range & Verification Details |
|---|---|
| Standard Specification | ASTM A193 / ASME SA 193 Grade B6, Class 1 and Class 2 |
| Base Metallurgy | 13% Chromium Martensitic Stainless Steel (AISI 410 / UNS S41000 / W.Nr. 1.4006 / 1.4021) |
| Product Forms | Heavy Hex Head Bolts, Stud Bolts, Hex Nuts, Socket Head Cap Screws, Fully Threaded Rods, Washers |
| Dimensional Standards | ASME B18.2.1, ASME B18.2.2, ASME B18.3, ASME B18.31.2, DIN 931, DIN 933, DIN 934, DIN 976, ISO 4014, ISO 4017 |
| Diameter Range | Metric: M6 to M100 | Imperial: 1/4″ to 4.0″ nominal diameter |
| Thread Configuration | UNC, UNF, 8-UN, Metric Coarse, Metric Fine (Class 2A / 2B fit tolerance) |
| Heat Treatment Status | Hardened and tempered at 1100°F (593°C) minimum in calibrated furnace facilities |
| Surface Protection | Plain oiled, Bright zinc electroplated, Hot-dip galvanised, PTFE / Xylan coated, Cadmium, Phosphate |
| Corrosion Compliance | NACE MR0175 / ISO 15156 and NACE MR0103 for sour gas and petrochemical line services |
| Origin of Steel Melt | Fully traceable prime melted steel sourced from approved mills in South Korea, Japan, India & Europe |
Material Characterisation
Chemical Composition & Metallurgy (AISI 410 / UNS S41000)
Grade B6 fasteners rely on a precisely controlled chromium-carbon ratio. This allows the alloy to form a martensitic microstructure upon rapid cooling (quenching) followed by tempering to eliminate brittleness, while maintaining sufficient free chromium to inhibit oxidation in steam lines and chemical processes.
| Grade Specification | Carbon (C) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Silicon (Si) | Chromium (Cr) |
|---|---|---|---|---|---|---|
| ASTM A193 Grade B6 (Min.) | 0.080% | — | — | — | — | 11.50% |
| ASTM A193 Grade B6 (Max.) | 0.150% | 1.000% | 0.040% | 0.030% | 1.000% | 13.50% |
Mechanical Integrity
Mechanical Properties, Tensile Strength & Hardness Verification
| Designation | Nominal Size Range | Tensile Strength min. (ksi / MPa) | Yield Strength 0.2% min. (ksi / MPa) | Elongation in 4D min. (%) | Reduction of Area min. (%) | Maximum Hardness |
|---|---|---|---|---|---|---|
| Grade B6 | Up to 4.0″ (M100) incl. | 110 ksi / 760 MPa | 85 ksi / 585 MPa | 15% | 50% | 241 HBW / 23 HRC |
| Grade B6X | Up to 4.0″ (M100) incl. | 90 ksi / 620 MPa | 70 ksi / 485 MPa | 16% | 50% | 26 HRC max. |
Dimensional Standard
ASME SA 193 Gr B6 Metric Hex Head Bolts (ASME B18.2.1 / DIN 931)
Dimensions below cover precision-forged metric hex head bolts used in flanged joints, high-pressure equipment, and structural piping supports.
| Nominal Size (D) | Body Diameter (mm) | Head Height (mm) | Width Across Flats (mm) | Across Corners (mm) | ||||
|---|---|---|---|---|---|---|---|---|
| Max | Min | Max | Min | Max | Min | Max | Min | |
| M10 | 10.00 | 9.78 | 6.63 | 6.17 | 17.00 | 15.73 | 18.48 | 17.77 |
| M12 | 12.00 | 11.73 | 7.76 | 4.24 | 19.00 | 17.73 | 20.78 | 20.03 |
| M14 | 14.00 | 13.73 | 9.09 | 8.51 | 22.00 | 20.67 | 24.25 | 23.35 |
| M16 | 16.00 | 15.73 | 10.32 | 9.68 | 24.00 | 23.67 | 27.71 | 26.75 |
| M20 | 20.00 | 19.67 | 12.88 | 12.12 | 30.00 | 29.16 | 34.64 | 32.95 |
| M24 | 24.00 | 23.67 | 15.44 | 14.56 | 36.00 | 35.00 | 41.57 | 39.55 |
| M30 | 30.00 | 29.67 | 19.48 | 17.92 | 46.00 | 45.00 | 53.12 | 50.85 |
| M36 | 36.00 | 35.61 | 23.38 | 21.63 | 55.00 | 53.80 | 63.51 | 60.79 |
| M42 | 42.00 | 41.38 | 26.97 | 25.03 | 65.00 | 62.90 | 75.06 | 71.71 |
| M48 | 48.00 | 47.38 | 31.07 | 28.93 | 75.00 | 72.60 | 86.60 | 82.76 |
| M56 | 56.00 | 55.26 | 36.20 | 33.80 | 85.00 | 82.20 | 98.15 | 93.71 |
| M64 | 64.00 | 63.26 | 41.32 | 38.68 | 95.00 | 91.80 | 109.70 | 104.65 |
| M72 | 72.00 | 71.26 | 46.45 | 43.55 | 105.00 | 101.40 | 121.24 | 115.60 |
| M80 | 80.00 | 79.26 | 51.58 | 48.42 | 115.00 | 111.00 | 132.72 | 126.54 |
| M90 | 90.00 | 89.13 | 57.74 | 54.26 | 130.00 | 125.50 | 150.11 | 143.07 |
| M100 | 100.00 | 99.13 | 63.90 | 60.10 | 145.00 | 140.00 | 167.43 | 159.60 |
Heavy Hex Standard
ASME SA 193 / A194 B6 Hex Nuts Dimensional Chart (ASME B18.2.2)
| Nominal Size (Inches) | Basic Thread Decimal | Width Across Flats (F) | Width Across Corners (G) | Thickness (H) | |||
|---|---|---|---|---|---|---|---|
| Max | Min | Max | Min | Max | Min | ||
| 1/4″ | 0.2500 | 0.438 | 0.428 | 0.505 | 0.488 | 0.226 | 0.212 |
| 5/16″ | 0.3125 | 0.500 | 0.489 | 0.577 | 0.557 | 0.273 | 0.258 |
| 3/8″ | 0.3750 | 0.562 | 0.551 | 0.650 | 0.628 | 0.337 | 0.320 |
| 1/2″ | 0.5000 | 0.750 | 0.736 | 0.866 | 0.840 | 0.448 | 0.427 |
| 5/8″ | 0.6250 | 0.938 | 0.922 | 1.083 | 1.051 | 0.559 | 0.535 |
| 3/4″ | 0.7500 | 1.125 | 1.088 | 1.299 | 1.240 | 0.665 | 0.617 |
| 7/8″ | 0.8750 | 1.312 | 1.269 | 1.516 | 1.447 | 0.776 | 0.724 |
| 1″ | 1.0000 | 1.500 | 1.450 | 1.732 | 1.653 | 0.887 | 0.831 |
| 1-1/8″ | 1.1250 | 1.688 | 1.631 | 1.949 | 1.859 | 0.999 | 0.939 |
| 1-1/4″ | 1.2500 | 1.875 | 1.812 | 2.165 | 2.066 | 1.111 | 1.047 |
| 1-1/2″ | 1.5000 | 2.250 | 2.175 | 2.598 | 2.480 | 1.335 | 1.245 |
| 1-3/4″ | 1.7500 | 2.625 | 2.538 | 3.031 | 2.893 | 1.540 | 1.460 |
| 2″ | 2.0000 | 3.000 | 2.900 | 3.464 | 3.306 | 1.763 | 1.675 |
| 2-1/2″ | 2.5000 | 3.750 | 3.625 | 4.330 | 4.133 | 2.209 | 2.105 |
Installation Engineering
ASTM A193 Grade B6 Bolt Torque Recommendations
The tightening torque values shown below are computed for clean, lightly oiled threads with a target pre-stress load conforming to standard pressure vessel and flange joint design practices.
| Nominal Bolt Diameter (Inches) | Thread Pitch (UNC / 8UN) | 30% Initial Torque (ft-lbs) | 70% Torque Stage (ft-lbs) | 100% Final Target Torque (ft-lbs) |
|---|---|---|---|---|
| 1/2″ | 13 UNC | 16 | 36 | 52 |
| 9/16″ | 12 UNC | 23 | 53 | 75 |
| 5/8″ | 11 UNC | 31 | 73 | 104 |
| 3/4″ | 10 UNC | 55 | 129 | 184 |
| 7/8″ | 9 UNC | 71 | 166 | 237 |
| 1″ | 8 UN | 107 | 249 | 356 |
| 1-1/8″ | 8 UN | 127 | 297 | 424 |
| 1-1/4″ | 8 UN | 179 | 417 | 596 |
| 1-3/8″ | 8 UN | 186 | 435 | 622 |
| 1-1/2″ | 8 UN | 246 | 574 | 821 |
| 1-5/8″ | 8 UN | 191 | 445 | 636 |
| 1-3/4″ | 8 UN | 240 | 561 | 801 |
| 2″ | 8 UN | 366 | 853 | 1219 |
| 2-1/4″ | 8 UN | 529 | 1234 | 1762 |
| 2-1/2″ | 8 UN | 733 | 1709 | 2442 |
| 3″ | 8 UN | 1289 | 3008 | 4297 |
Comprehensive Comparison
ASTM A193 Grade B6 vs. Other High-Strength Fastener Grades
| ASTM Grade | Base Material Type | Nominal Composition | Tensile Strength min. (ksi) | Yield Strength min. (ksi) | Max Hardness | Primary Application Environment |
|---|---|---|---|---|---|---|
| Grade B6 | Martensitic SS (410) | 13% Cr | 110 | 85 | 241 HBW | Steam service, non-severe sour gas, refining heaters |
| Grade B7 | Cr-Mo Alloy Steel | AISI 4140 / 4142 | 125 | 105 | 321 HBW / 35 HRC | General high-pressure flanges and valves up to 400°C |
| Grade B8 (Cl. 1) | Austenitic SS (304) | 18Cr - 8Ni | 75 | 30 | 223 HBW | Chemical, marine and cryogenic piping applications |
| Grade B8M (Cl. 2) | Austenitic SS (316) | 18Cr - 12Ni - 2Mo | 110 | 95 | 321 HBW | Chloride-rich offshore marine & petrochemical environments |
| Grade B16 | Cr-Mo-V Alloy Steel | AISI 4340 + Vanadium | 125 | 105 | 321 HBW | Superheated high pressure steam headers up to 538°C |
Global Reference Cross-Index
DIN to ISO Standard Conversion for Fasteners
| DIN Standard | ISO Standard | Product Category | DIN Standard | ISO Standard | Product Category |
|---|---|---|---|---|---|
| DIN 931 | ISO 4014 | Hex head bolt with shank | DIN 934 | ISO 4032 | Hexagon nut standard |
| DIN 933 | ISO 4017 | Hex head bolt full thread | DIN 985 | ISO 10511 | Nylon insert lock nut |
| DIN 912 | ISO 4762 | Socket head cap screw | DIN 125 | ISO 7089 | Flat washer plain |
| DIN 976 | ISO 898-1 | Threaded rod continuous | DIN 7991 | ISO 10642 | Countersunk socket screw |
Global Reach
International Project Supply & Global Port Delivery
Rajtilak Metal supplies project orders of ASTM A193 Grade B6 fasteners across 20+ countries with complete export packing in heavy wooden crates with anti-corrosion barrier protection.
NorwayItalyGermanyUnited KingdomUAESaudi ArabiaQatarOmanKuwaitSingaporeMalaysiaIndonesiaPhilippinesAustraliaUnited StatesBrazilEgypt
Require Certified ASTM A193 Grade B6 Fasteners?
Our engineering team verifies specifications, threading tolerances, coating requirements, and project NDT schedules prior to issuing certified quotations.
Technical FAQ
Frequently Asked Questions About ASTM A193 Grade B6
What is the difference between ASTM A193 Grade B6 and B6X?
ASTM A193 Grade B6 is heat-treated to achieve a minimum tensile strength of 110 ksi and yield of 85 ksi. Grade B6X is tempered at a higher temperature to produce lower hardness (26 HRC maximum) and lower yield strength (70 ksi minimum), making it specifically suitable for sour gas environments compliant with NACE MR0175 / ISO 15156.
Which mating nuts are recommended for ASTM A193 Grade B6 bolts?
ASTM A194 Grade 6 heavy hex nuts (manufactured from tempered AISI 410 stainless steel) are the standard matching nuts for Grade B6 bolting assemblies to guarantee mechanical parity and uniform thermal expansion.
What inspection documentation accompanies each shipment?
Every batch is supplied with an EN 10204 3.1 inspection certificate containing full ladle chemical analysis, tensile testing, yield proof load, Charpy V-notch impact values (if specified), hardness readings, and heat lot numbers physically stamped on every bolt head or stud face.
Can Grade B6 bolts be provided with protective coatings?
Yes. We supply plain finished, zinc-electroplated, PTFE/Xylan coated (blue, green, yellow), hot-dip galvanized, cadmium plated, and phosphate coated ASTM A193 Grade B6 fasteners designed for high-corrosion offshore or chemical applications.
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