Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
ASTM A193/A193M Grade B6X Stud Bolts – UNS S41000
Reduced-hardness Type 410 martensitic stainless steel stud bolts for hydrogen service and sour gas environments requiring NACE-compatible hardness limits.
ASTM A193/A193M Grade B6X Stud Bolts are manufactured from UNS S41000 Type 410 martensitic stainless steel and represent a controlled-hardness modification of the standard Grade B6 specifically developed for service environments where susceptibility to sulfide stress corrosion cracking (SSC) and hydrogen-induced cracking (HIC) is a primary concern, such as sour gas and wet hydrogen sulfide environments governed by NACE MR0175/ISO 15156 standards. By specifying a lower maximum hardness compared to standard B6 — typically Rockwell C 26 maximum — Grade B6X limits the susceptibility of the martensitic microstructure to these environmentally-assisted cracking mechanisms while retaining sufficient mechanical strength for pressure vessel and pipeline flange bolting service. The 12% chromium content continues to provide the moderate corrosion resistance characteristic of Type 410, and the lower hardness is achieved through appropriate tempering at higher temperatures. Grade B6X stud bolts are widely specified in sour oil and gas production facilities, refinery amine treaters, sour water strippers, and pipeline flanges where H2S-containing streams make standard higher-hardness materials unacceptable.
ASTM A193/A193M Grade B6X Chemical Composition - Ferritic Steels
| Grade | Description and
UNS Designation |
C | Mn | P | S | Si | Cr |
|---|---|---|---|---|---|---|---|
| ASTM A193 Grade B6X | 12% Cr (410), S41000 | 0.08-0.15 | 1.00 | 0.040 | 0.030 | 1.00 | 11.5-13.5 |
| Product Analysis VariationB | 0.01 over | 0.03 | 0.005 | 0.005 | 0.05 | 0.15 |
ASTM A193/A193M Grade B6X Mechanical Requirements - Ferritic Steels (Inch)
| Grade | Diameter, in. | Minimum Tempering Temperature, °F |
Tensile Strength, min, ksi | Yield Strength, min, 0.2 % offset, ksi |
Elongation in 4D, min, % | Reduction of Area, min, %Reduction of Area, min, % | Hardness, max |
|---|---|---|---|---|---|---|---|
| ASTM A193 Grade B6X | up to 4, incl | 1100 | 90 | 70 | 16 | 50 | 26 HRC |
ASTM A193/A193M Grade B6X Mechanical Requirements - Ferritic Steels (Metric)
| Class | Diameter,
[mm] |
Min.Tempering
Temp. °C |
Tensile Strength,
min, MPa |
Yield Strength,min,
.2% offset, MPa |
Elongation in 4D,
min, % |
Reduction of Area, min, % | Hardness,
max |
|---|---|---|---|---|---|---|---|
| ASTM A193 Grade B6X | up to M100, incl | 593 | 620 | 485 | 16 | 50 | 26 HRC |
ASTM A193/A193M Grade B6X Bolting Components Marking - Ferritic Steels
| Grade | Grade Symbol |
|---|---|
| ASTM A193 Grade B6X | TB B6X |
Related ASTM A193 Grades & ASME Companion Dimensions
Frequently Asked Questions
- What is ASTM A193 Grade B6X?
- ASTM A193 Grade B6X is a bolting material covering 13% Cr martensitic, modified strength (UNS S41000). Used in high-temperature, high-pressure flange, pressure-vessel and heat-exchanger bolting service per ASTM A193/A193M.
- What is the UNS designation for ASTM A193 Grade B6X?
- The UNS designation for ASTM A193 Grade B6X is UNS S41000. This corresponds to 13% Cr martensitic, modified strength. The UNS code is universal across ASTM, ASME (SA-193), PED 2014/68/EU and NORSOK material specifications.
- What is the service envelope for Grade B6X?
- Grade B6X (13% Cr martensitic) is used up to ~480 °C (900 °F) in moderately corrosive service. The 13% Cr provides general atmospheric corrosion resistance; it is not chloride-resistant.
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