Standards
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
L19 Race-Grade 12-Point Bolts
L19 (race-grade alloy steel, AISI 8740 derivative with controlled sulphur and inclusion shape) is widely used in top-end race connecting-rod bolts, NHRA Pro Stock main studs, and high-boost engine fasteners because it can be heat-treated to 270 ksi tensile while keeping the elongation and impact toughness needed for cyclic-load reliability. The 12-point head is the standard drive geometry on race-grade L19 bolts because the twelve splines allow the very high preload torque needed for connecting-rod and main-cap clamping without camming the wrench off the head.
TorqBolt manufactures the full 12-point geometry range in L19 (rod bolts, main studs, head studs, flywheel bolts) to AS9100D Rev D and ISO 9001:2015 quality systems. Each bolt head carries the struck tB manufacturer ligature plus the L19 grade marking, and every lot ships with a mill test report (MTC 3.1 standard, MTC 3.2 critical with hardness, tensile, magnetic-particle and dimensional inspection records). L19 is delivered shot-peened and rolled-thread-after-heat-treatment by default to maximise fatigue life under reverse-cycle loading.
For deep L19 metallurgy, chemistry, heat treatment, and equivalent grades see torqbolt.com.
Specifications We Produce
- MS21250, 160 ksi 12-point aerospace bolt
- NAS1351, close-tolerance 12-point
- AS3216, 180 ksi superalloy 12-point
- NAS6303 through NAS6320 tension series
Typical Applications
- Aerospace engine + structural bolting
- Motorsport head studs, rod bolts, main cap bolts
- Diesel-truck performance head studs
- Industrial high-temperature bolting
When to specify this alloy over alternatives
Alloy choice in 12-point bolting is set by the combination of tensile target, service temperature, corrosion environment, and traceability requirement. The default for a generic 160 ksi aerospace bolt is A286 because the supply chain is mature, the AMS specs (5731 / 5732 / 5737) are well documented, and oxidation resistance is good to 700 deg C.
Step up to Inconel 718 when service temperature exceeds 700 deg C or when the joint sees aggressive cyclic stress in jet-engine duty. Step up to MP35N when tensile target is 220+ ksi and the environment is sour-service or saline. Use Ti-6Al-4V when the 56 percent weight savings vs steel matters more than tensile (race-engine main caps, aerospace airframe pylon clip-ups). Use 17-4 PH H1025 when corrosion resistance and 180 ksi tensile both matter and budget rules out cobalt-nickel.
Certification pack with each lot
Mill test report MTC 3.1 ships with every lot at no additional cost: chemistry per the alloy spec, mechanical properties (tensile, yield, elongation at fracture, hardness), microstructure note, and heat-treatment cycle. MTC 3.2 adds third-party witness inspector signature on every test event from raw-bar receiving through final lot acceptance and is required by most aerospace primes for tier-1 critical-service joints. Add MTC 3.2 in the RFQ if your drawing or PO calls for it.
Request a Quote
RFQ to info@torqbolt.com or call +91-22-66157017. Mill test report (MTC 3.1 or 3.2 critical) ships with every lot.
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