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Incoloy 800H Square Bar

Square Bar Size Range

Cold-Drawn and Hot-Rolled Routes

Cold-drawn square bar (default for smaller sizes up to 1-1/2 in) is hot-rolled near-square then drawn through a square die in 2 to 3 passes with intermediate process-anneal. The cold-draw fixes the side dimension to h11 tolerance and delivers a bright finish. Hot-rolled square bar (default above 1-1/2 in) is supplied with a pickled-and-shot-blasted surface and looser side tolerance. Both routes finish with full solution anneal at 2050 deg F per ASTM B408 paragraph 7, water quench to lock in grain size 5 or coarser. For shaft-key applications cold-drawn delivers tight enough tolerance to fit the keyway without skim machining; for die blanks and structural members hot-rolled is adequate and saves cost.

Chemistry and Mechanical Properties

UNS N08810 chemistry per ASTM B408: Ni 30 to 35, Cr 19 to 23, 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. Solution-annealed mechanical properties: tensile 75 ksi (515 MPa) min, yield 30 ksi (205 MPa) min, elongation 30 percent min, hardness HRB 70 to 90, grain size ASTM 5 or coarser. Creep design stress envelope to 815 deg C (1500 deg F) published in ASME Section II Part D. Full mechanical data; ASME design stress curves.

Typical Applications

• Shaft keys - parallel and tapered keys per DIN 6885 and ASME B17.1 for pumps, mixers and compressors running in petrochemical-process service
• Machined fittings with square-section adapter features (handles, lever arms)
• Die blanks for hot-forming small-quantity high-temperature parts
• Structural reinforcement in reformer-header support brackets, furnace-tube hangers and fired-heater grid supports
• Square-headed bolts blank stock (downstream of round bar for hex-head)
• Sliding-block stock for high-temperature linkage and damper actuation
• Custom-machined adapter blocks where a flat reference face is required on all 4 sides

Manufacturing and Inspection

• Mill source: Special Metals, VDM, Outokumpu or ATI - verified 3.1 / 3.2 certificate, full traceability
• Cold-draw or hot-roll per the size and downstream application route
• Solution anneal at 2050 deg F (1121 deg C) and water quench per ASTM B408 paragraph 7
• Side dimension verification: digital caliper plus go/no-go at both ends and mid-length
• Surface check: visual + dye-penetrant on sample per heat
• Tensile + yield + elongation per ASTM A370 on coupon per heat lot
• Hardness per ASTM E18 - HRB 70 to 90 in solution-annealed condition
• Grain size per ASTM E112 - acceptance grade 5 or coarser
• Ultrasonic per ASTM A388 on side dimension 38 mm and above
• Heat marking per ASTM B408 paragraph 12 with mill mark and paint colour band

Companion Forms and Standards

For round profiles see round bar; for hex profiles see hex bar; for flat profiles see flat bar. Parent feedstock standard ASTM B408 / ASME SB-408. For shaft-key dimensional standards, see DIN 6885 (parallel keys) and ASME B17.1 (ANSI keys). For fastener downstream products see fasteners.

Square Bar FAQ

Q. Why use 800H for shaft keys instead of carbon steel or stainless?
In reformer-furnace and fired-heater service, pumps and mixers carry shafts running at 400 to 800 deg C. Carbon-steel keys oxidize and seize; 304/316 stainless creeps and loses keyway fit; 800H holds its creep strength and oxidation resistance to 815 deg C in continuous service. The key remains free-moving over the service life of the equipment.

Q. Cold-drawn vs hot-rolled - which for shaft keys?
Cold-drawn. The h11 tolerance on the side dimension matches the DIN 6885 / ASME B17.1 keyway tolerance directly, so the key fits the keyway without skim machining. Hot-rolled would require a finishing pass to clean up the side.

Q. Maximum square bar side you can supply?
Cold-drawn to 65 mm (2-1/2 in) is the practical limit. Hot-rolled to 100 mm (4 in) is available on indent with 6 to 8 week lead time. Above 100 mm, square sections are produced by hot-forging from round billet stock - in that range round bar plus machining is more economical.

Q. Is 800H square bar qualified for NACE MR0103 sour service?
Yes in solution-annealed condition. Hardness 70 to 90 HRB sits below the NACE MR0103 / ISO 17945 limit of 22 HRC (237 HV). Compliance statement included on the EN 10204 3.1 / 3.2 certificate. Cold-drawn material exceeds the NACE hardness limit and is not sour-qualified without subsequent annealing.

Request a Quote on Incoloy 800H Square 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.