1. Home
2. » Fasteners
3. » Hex Bar

Incoloy 800H Hex Bar

Hex Bar Size Range and Across-Flats Dimensions

Cold-Drawn vs Annealed Condition

Hex bar is supplied in two condition routes. Cold-drawn (default) is hot-rolled to near-hex profile then cold-drawn through a hex die in 2 to 3 passes with intermediate process-anneal; the final draw fixes the across-flats dimension to h11 tolerance and the surface to Ra 0.4 to 0.8 micron bright finish. Tensile in cold-drawn condition runs 85 to 100 ksi (585 to 690 MPa), hardness HRB 85 to 95. Solution-annealed is cold-drawn material followed by full anneal at 2050 deg F per ASTM B408 paragraph 7 and quench - tensile drops to 75 ksi (515 MPa), hardness HRB 70 to 90, ductility recovered to 35 percent elongation. Annealed is preferred for downstream cold-forming (nut upset, thread roll) and for sour-service compliance under NACE MR0103. Cold-drawn is preferred for direct screw-machine work where dimensional stability is the priority.

Chemistry and Mechanical Properties

UNS N08810 chemistry per ASTM B408: Ni 30.0 to 35.0, Cr 19.0 to 23.0, Fe balance, C 0.05 to 0.10, Al 0.15 to 0.60, Ti 0.15 to 0.60, Al+Ti 0.30 to 1.20, Si 1.0 max, Mn 1.5 max, S 0.015 max, Cu 0.75 max. Solution-annealed condition: tensile 75 ksi (515 MPa) min, yield 30 ksi (205 MPa) min, elongation 30 percent min in 4D, hardness HRB 70 to 90, grain size ASTM 5 or coarser per E112. Full chemistry; full mechanical data.

Common Applications

• Hex nut blanks - M6 through M64, machined from AF 10 through AF 100 mm hex bar
• Heavy hex nut blanks per ASME B18.2.2 - larger AF dimensions matching the heavy-hex envelope
• Coupling nuts machined from oversize hex bar for thread-rod joining
• Valve stem heads with integrated hex-drive feature
• Hex-driven pump-shaft adjusters in chemical-process service
• Custom hex-section adapters and machined fittings
• Pipe-plug hex heads for reformer-header drain connections

Manufacturing and Inspection

• Mill source: Special Metals, VDM, Outokumpu or ATI verified mill certificate
• Cold-draw route: hot-rolled near-hex blank, 2 to 3 cold-draw passes with intermediate process-anneal
• Across-flats verification: digital caliper plus go/no-go gauge at each end and mid-length
• Surface inspection: visual plus dye-penetrant on sample per heat lot
• Hardness per ASTM E18 - HRB 70 to 90 in solution-annealed, HRB 85 to 95 in cold-drawn
• Grain size per ASTM E112 - grade 5 or coarser per ASTM B408
• Tensile + yield + elongation per ASTM A370 on coupon per heat
• Eddy current per ASTM E1606 on smaller AF (up to AF 30 mm)
• Ultrasonic per ASTM A388 on larger AF (above AF 50 mm)
• Heat number marking per ASTM B408 paragraph 12 with mill mark and paint colour band

Standards Reference

• ASTM B408 / ASME SB-408 - Nickel-Iron-Chromium alloy rod and bar (the parent feedstock standard)
• ASTM F468 - Non-ferrous bolts, hex cap screws and studs (downstream fastener standard)
• ASTM F467 - Non-ferrous nuts (downstream nut standard, matched to F468 bolts)
• ASME B18.2.2 - Hex nuts dimensional specification
• DIN 934 / ISO 4032 - metric hex nuts (matching the European AF series)
• EN 10204 type 3.1 / 3.2 - inspection certification
• NACE MR0103 / ISO 17945 - refinery sour-service compliance (where required)

Hex Bar FAQ

Q. Why cold-drawn rather than hot-rolled hex bar?
Cold-drawn delivers the tight across-flats tolerance (h11) that screw-machine and CNC-mill operations require for repeatable nut and bolt-head dimensions. Hot-rolled hex profile carries +/- 0.5 mm or worse AF tolerance and would force the machinist to take an additional skim cut on every face. Cold-drawn also delivers a bright surface finish that needs no preparation before threading.

Q. What sizes are nuts machined from this hex bar - DIN, ISO or ANSI?
All three are supported because AF dimensions overlap. Example - AF 24 mm matches ISO 4032 M16 (24 AF), DIN 934 M16 (24 AF) and ASME B18.2.2 5/8 in (15/16 in = 23.8 mm AF). Specify the target nut standard on the order and the AF dimension follows. For ASME B18.2.2 heavy-hex, specify the heavy-hex AF (M16 heavy = 27 mm vs standard 24 mm).

Q. Can hex bar be supplied with NACE MR0103 sour-service certification?
Yes - in the solution-annealed condition, 800H hex bar meets NACE MR0103 / ISO 17945 hardness limits (22 HRC max, 237 HV equivalent). The compliance statement is added to the EN 10204 type 3.1 / 3.2 certificate. For sour service, specify annealed (not cold-drawn) condition - cold-drawn carries higher hardness that would fail the NACE limit.

Q. What is the maximum AF size you can supply as cold-drawn?
Practical maximum for cold-drawn is AF 75 mm (M48 nut). Above AF 75 mm the cold-draw force and die wear become uneconomical; AF 85 mm and 100 mm are supplied as hot-rolled then peeled-machined to AF tolerance. The downstream nut machining cost is similar either way for the larger sizes.

Request a Quote on Incoloy 800H Hex Bar

Send the project drawing, cut list, size, finish, certification class (3.1 or 3.2) and any PMI / NACE MR0103 / cut-to-length add-ons to our sales desk. Call +91-22-66157017 or email info@torqbolt.com for a 24-hour response.