What is the maximum temperature for Incoloy 800 fasteners?

Alloy 718 is rated for continuous service up to approximately 1300°F (704°C). It retains most of its strength to about 1200°F and can survive brief excursions higher, though the strengthening precipitate begins to coarsen and over-age above roughly 1350°F. For sustained service above 800°C, choose Inconel 600 or Inconel 601 instead.

Is Incoloy 800 a type of stainless steel?

No. Stainless steel is an iron-based alloy with a minimum of about 10.5% chromium. Incoloy 800 is a nickel-based superalloy with 50-55% nickel and iron as the balance.

What is the difference between Incoloy 800 and Inconel 625 fasteners?

718 is precipitation-hardened and 625 is solid-solution strengthened. That makes 718 roughly twice as strong, but 625 works to a higher temperature and offers superior pitting and crevice resistance in seawater and acids.

What heat treatment do Incoloy 800 fasteners require?

Solution treatment at roughly 940-1010°C followed by a two-stage age: 8 hours at 718°C, furnace cool to 621°C, then a further 8 hours before air cooling.

Can Incoloy 800 fasteners be used at cryogenic temperatures?

Yes. Alloy 718 retains excellent toughness and ductility down to approximately -253°C (-423°F) with no ductile-to-brittle transition.

What sizes of Incoloy 800 fasteners do you manufacture?

Bolts and screws from EN 10204 3.1/3.2 MTC (3/16 inch to 4 inch), nuts and washers from M3 to M56 (3/16 inch to 2 inch), and lengths from 3 mm to 200 mm as standard. Larger diameters and non-standard lengths are produced to drawing.

Incoloy 800, 800H & 800HT Fasteners — Bolts, Nuts, Studs, Screws & Washers

ASTM B408 / ASME SB 408 / UNS N08800 Fasteners Manufactured for Extreme Heat & Corrosion Resistance

ISO 9001:2015 Certified

EN 10204 3.1/3.2 MTC

PED 2014/68/EU Approved

50+ Countries Exported

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What Are Incoloy 800 Fasteners?

Incoloy 800 is an iron-nickel-chromium alloy. Incoloy and Inconel are separate alloy families under the same trademark holder: Inconel grades are nickel-based, typically above 50% nickel, while Incoloy grades are iron-based with nickel added — which is what makes 800 materially cheaper than Alloy 600 at comparable oxidation performance designed to resist oxidation, carburisation and general corrosion at high temperature. The published ~1100°C figure is a scaling and oxidation limit for the alloy in sheet and tube form; it is not a limit at which a bolted joint retains preload. Load-bearing capability is governed by creep and stress-rupture behaviour, which is why 800H and 800HT exist as separate grades and why sustained high-temperature bolting should be specified in one of them rather than in standard 800. Tell us the metal temperature and hold time and we will confirm the grade and the design basis. Unlike conventional austenitic stainless steels (such as grade 304 or 316), which distort and lose mechanical strength at elevated temperatures, Incoloy 800 retains excellent creep and stress-rupture strength, making it the material of choice for structural fasteners in furnaces, heat exchangers, and high-temperature process piping.

Unifit Fastener stocks and manufactures the full family of Incoloy 800 & 800HT fasteners, including matching Incoloy 800/800HT round bars, tube plugs, and washers — giving project teams a single, consistent-heat-lot source for complete assemblies.

Incoloy 800 Fastener Product Range

Incoloy 800 Bolts

Incoloy 800 Nuts

Incoloy 800 Washers

Incoloy 800 Screws

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Technical Data

Incoloy 800 vs 800H vs 800HT — Key Differences

Grade	UNS	Carbon Content	Best Suited For
Incoloy 800	N08800	0.10% max	General corrosion resistance, moderate temperature service
Incoloy 800H	N08810	0.05–0.10%	Higher creep & stress-rupture strength for sustained high heat
Incoloy 800HT	N08811	0.06–0.10% + controlled Al+Ti (min 0.85%)	Maximum creep strength, prolonged exposure above 1000°C

Incoloy 800 Fasteners Specification

Parameter	Specification
Grade	Incoloy 800 / 800H / 800HT
Specification	ASTM B408 / ASME SB 408, UNS N08800/N08810/N08811, Werkstoff Nr. 1.4876
International Standards	DIN, ISO, JIS, GB, IS, BS, ASTM and all international standards
Size Range	M3–M56 / 3/16" to 2" (custom up to M100 / 4" on request)
Length	3 mm – 200 mm (custom sizes available)
Threads Available	UNC, UNF, UNR, UNEF, METRIC, BSW, BSF
Manufacturing Process	Hot forging (up to M36/1-1/2"), Cold forging (M2–M24), CNC machining (up to M100/4")
Surface Coating	Zinc, Black Oxide, Xylan, PTFE/Teflon, Nickel Plated, Dacromet, HDG
Test Certificates	EN 10204 3.1 / 3.2, PMI Test Report, Third Party Inspection Report
Packing	Bulk carton, pallet, wooden boxes, or as per customer requirement
Origin	India (manufactured to European & American standards)

Incoloy 800 Fasteners Chemical Composition (%)

Grade	C	Mn	Si	S	Cu	Fe	Ni	Cr	Ti	Al
Incoloy 800	0.10 max	1.5 max	1.0 max	0.015 max	0.75 max	39.5 min	30–35	19–23	0.15–0.60	0.15–0.60
Incoloy 800H	0.05–0.10	1.5 max	1.0 max	0.015 max	0.75 max	39.5 min	30–35	19–23	0.15–0.60	0.15–0.60
Incoloy 800HT	0.06–0.10	1.5 max	1.0 max	0.015 max	0.75 max	39.5 min	30–35	19–23	0.15 – 0.60	0.15 – 0.60

Incoloy 800 Fasteners Mechanical & Physical Properties

Property	Value
Density	7.94 g/cm³
Melting Range	1357–1385°C (2475–2525°F)
Tensile Strength	Psi – 75,000 min, MPa – 520 min
Yield Strength (0.2% Offset)	Psi – 30,000 min, MPa – 205 min
Elongation	30% min
Max Service Temperature	Up to 1100°C (2012°F)

Incoloy 800 Fasteners Equivalent Grades

Standard	UNS	Werkstoff Nr.	EN	JIS	BS	GOST	AFNOR
Incoloy 800	N08800	1.4876	X10NiCrAlTi32-20	NCF 800	NA 15	3И670	Z8NC32-21
Incoloy 800H	N08810	1.4958/1.4876	X10NiCrAlTi32-20	NCF 800H	NA 15(H)	3И670	Z8NC32-21
Incoloy 800HT	N08811	1.4959/1.4876	X8NiCrAlTi32-21	NCF 800HT	NA 15(HT)	3И670	—

Torque Chart (Incoloy 800/800H/800HT Bolts — Reference)

Nominal Diameter	Threads/in	Torque ft-lb (Dry)	Torque ft-lb (Lubricated)
1/4"	20	3.3	2.5
3/8"	16	12.2	9.1
1/2"	13	42.8	36 ksi
3/4"	10	105	79
1"	8	253	190
1-1/2"	6	767	575

Comparison Table: Incoloy 800 vs Related High-Nickel Alloys

Alloy	UNS	Max Service Temp.	Key Strength	Typical Use
Incoloy 800/800H/800HT	N08800/10/11	Up to 1100°C	Oxidation & carburization resistance, creep strength	Furnaces, heat exchangers, petrochemical
Incoloy 825	N08825	Up to 550°C	Resistance to acidic & chloride environments	Chemical processing, oil & gas
Inconel 600	N06600	Up to 1093°C	Resistance to chloride-ion stress corrosion cracking	Nuclear, aerospace, chemical
Inconel 625	N06625	Up to 980°C	Exceptional fatigue & thermal-fatigue strength	Marine, aerospace, oil & gas
Monel 400	N04400	Up to 480°C	Excellent resistance to seawater & hydrofluoric acid	Marine, chemical processing

Incoloy 800 Fasteners Applications

Petrochemical & chemical processing plants (heat exchangers, reactors)
Power generation & nuclear power plants
Furnace components, muffles, and radiant tubes
Pulp and paper industry equipment
Heat-treatment industry fixtures and jigs
Ethylene and steam-methane reformer piping

Looking for the same performance in related nickel alloys? See our Inconel fasteners, Inconel 625 fasteners, and Inconel 718 fasteners ranges, all manufactured under the same quality system.

Manufacturing Process & Quality Control

Production Process

Hot Forging (large-diameter bolts and studs, up to M36/1-1/2" dia.)
Cold Forging (M2–M24 precision fasteners)
CNC Machining (custom and large-diameter items up to M100/4")
Threading & finishing to UNC/UNF/UNR/UNEF/METRIC standards
Surface coating (Zinc, Xylan, PTFE, Dacromet, Black Oxide, Nickel Plating)

Quality & Testing Facilities

Hardness Testing
Positive Material Identification (PMI) Testing
Intergranular Corrosion (IGC) Test
Chemical Analysis / Spectro Analysis
Mechanical Testing (Tensile & Proof Load)
Third-Party Inspection on Request

Certifications & Standards

ISO 9001:2015 Certified Manufacturing
EN 10204 3.1 & 3.2 Mill Test Certification
PED 2014/68/EU Compliant (where applicable)
Manufactured to ASTM B408 / ASME SB 408 / DIN 1.4876
Compliant with DIN, ISO, JIS, GB, IS, BS, GOST, AFNOR standards

See our complete fasteners standards guide for a breakdown of applicable international specifications, and learn more about Unifit Fastener as a certified manufacturer.

FAQ's About Incoloy 800 Fasteners

What is the difference between Incoloy 800, 800H, and 800HT fasteners?

The three grades share the same base UNS N08800 chemistry but differ mainly in carbon content and grain structure control. Incoloy 800 is used for general corrosion resistance; Incoloy 800H (higher, controlled carbon, coarser grain) offers improved creep and stress-rupture strength; Incoloy 800HT adds a minimum combined Aluminum + Titanium content of 0.85% for the highest creep strength at prolonged high temperatures above 1000°C.

What is the maximum operating temperature for Incoloy 800 fasteners?

Incoloy 800/800H/800HT fasteners can operate reliably at temperatures up to approximately 1100°C (2012°F), depending on the specific grade, load, and atmosphere (oxidizing, carburizing, or reducing).

Which standards apply to Incoloy 800 fasteners?

Incoloy 800 fasteners are commonly manufactured to ASTM B408, ASME SB 408, and Werkstoff Nr. 1.4876 (DIN), and are cross-referenced against ISO, JIS, BS, GOST, and AFNOR equivalents.

What sizes of Incoloy 800 bolts, nuts, and washers do you supply?

Unifit Fastener supplies Incoloy 800/800H/800HT fasteners from M3 to M56 (3/16" to 2") as standard stock, with custom sizes available up to M100 (4") and lengths from 3 mm to 200 mm.

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