Alloy 20 Bolts

Alloy 20 Bolts, Specifications & Dimensions

Alloy 20 bolts are externally threaded fasteners with an integral head, manufactured per ASME B18.2.1, ISO 4014/4017, and DIN 933/931. TorqBolt produces Alloy 20 bolts in metric (M6–M100) and imperial (1/4"–4") diameters with custom lengths from 10 mm up to 3000 mm.

Head Styles Available

Thread & Shank

Alloy 20 bolts are supplied with full or partial threading. Full-thread (UNC, UNF, ISO metric coarse/fine) for tension-only joints; partial-thread shank for shear loads. Thread fits per ASME B1.1 (Class 2A) or ISO 965 (6g) by default; tighter Class 3A / 4h6h on request.

Mechanical & Certification

Alloy 20 bolts achieve characteristic tensile, yield, and elongation per the source-material spec, with proof-load testing and hardness verification per ASTM F606 / ISO 898-1. Each lot ships with EN 10204 3.1 (or 3.2) certificates listing chemistry, mechanicals, hardness, and dimensional inspection. NACE MR0175 / ISO 15156 sour-service certification on request.

High-Mo Super-Austenitic Stainless (254 SMO, 904L, Alloy 20)

Super-austenitic stainless steels are high-Mo (≥6%), high-N austenitic alloys with chloride-pitting resistance approaching duplex grades while retaining austenitic formability.

254 SMO (S31254) is the benchmark with PREN ~43. 904L (N08904) is the original 4.5% Mo super-austenitic for sulfuric-acid plants. Alloy 20 (N08020) is Cu-bearing for hot sulfuric acid. AL-6XN (N08367) extends pitting resistance with 6.5%+ Mo.

Super-austenitic fasteners ship per ASTM A276 / A479 with ASTM G48 Method A pitting testing. Welding requires Ni-base filler (alloy 625 / C-276) to avoid Mo segregation.

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