Stainless Steel Bolts

Stainless Steel Bolt Manufacturers in India

Unifit Fastener is an India-based manufacturer and exporter of stainless steel bolts engineered for corrosion-critical, high-temperature and high-load service. We supply SS bolts across six austenitic grades — 304/304H/304L, 310/310S, 316/316L, 317/317L, 321 and 347/347H — to ASTM F593 and ISO 3506 requirements. The company has a wide variety of stainless steel fasteners in high grade, including 304/304H/304L, 310/310S, 316/316L, 317/317L, 321, and 347/347H, which are highly resistant to corrosion, heat, and mechanical stress. These grades render the products of Unifit as suitable in the industries where performance and durability are not a compromise.

Our bolts, nuts, screws, and washers are engineered to be used on long-lasting projects; they are used in marine work, desalination plants, chemical processing units, pumping stations, heavy engineering work, and large infrastructure projects. Our stainless steel bolts hold up in moisture-, chloride- and heat-exposed environments where carbon-steel fasteners corrode or lose preload — delivering long service life with minimal maintenance.

The modern manufacturing plant of Unifit Fastener has the capabilities of hot forging, high-tech CNC machining, and an accurate thread-rolling process to make fasteners of high dimensional precision and quality. They have the experience of providing both standard and custom-made fasteners, which have a smooth compatibility with various industrial needs and project specifications.

Unifit Fastener has a solid standing in the world with a presence in the Indian, Middle Eastern, European, and USA markets, as well as a reputation for reliability, consistency, and innovation. Whether the application is construction, automotive, renewable energy, petrochemical plant or pipeline infrastructure, we deliver stainless steel bolts that meet international quality standards and perform reliably over the full service life of the asset, meeting international quality requirements and contributing to long-term operation.

Request a Quote

Table of content

What are Stainless Steel Bolts?

Stainless steel bolts are high-performance fasteners manufactured from durable stainless steel alloys containing iron, chromium, and varying amounts of nickel and other strengthening elements. This specific blend gives the bolts outstanding protection against rust, corrosion, and temperature fluctuations. Thanks to their superior material properties, stainless steel bolts remain reliable even in challenging or corrosive environments where regular carbon steel bolts are likely to degrade or lose strength.

Stainless Steel Hex Bolts, SS Hex Head Bolts, Stainless Steel Head Bolts, SS Allen Cap Bolts, Stainless Steel Heavy Hex Bolts, Stainless Steel Carriage Bolts, Stainless Steel Anchor Bolts, Stainless Steel Anti-Theft Nuts and Bolts, Stainless Steel Hanger Bolts.

Stainless steel bolts grades

Stainless Steel 316Ti Hex Cap Screw

Stainless Steel 316Ti Hex Cap Screw

Stainless Steel 316L Machine Screw

Stainless Steel 316L Machine Screw

Stainless Steel 316L heavy hex bolt

Stainless Steel 316L heavy hex bolt

Stainless Steel 316H Flange Bolt

Stainless Steel 316H Flange Bolt

Stainless Steel 316H Allen Cap Screw

Stainless Steel 316H Allen Cap Screw

Stainless Steel 316 Carriage Bolt

Stainless Steel 316 Carriage Bolt

Choosing the Right Stainless Steel Fastener Grade

GradeBest For
A2 (304/304L)General industrial and indoor applications
A3 (321/347)Elevated temperature service
A4 (316/316L)Marine and chloride environments
904LSevere corrosion environments, acids, offshore and chemical processing

Specification of Stainless Steel Bolts

CategoryDetails
SpecificationsASTM F593 (bolts, screws & studs) and ASTM F594 (nuts) compliant; ISO 3506-1/-2 property classes A2-70, A4-70, A4-80.
Standards FollowedManufactured as per DIN, ISO, JIS, GB, IS, BS, ASTM, and other major international standards
Available SizesM3 to M100 • 3/16″ to 4″ • Custom sizes on request.
Length Range3 mm to 200 mm • Custom lengths can be produced
Dimensional StandardsDIN 931, 933, 934, 7991, 976, 125, and ASME B18.2.1 / B18.3
Thread TypesMETRIC, UNC, UNF, BSW, BSF, or special threads based on requirements
Thread ConfigurationUnified threads per ASME B1.1 (2A/3A – 2B/3B) and Metric threads per ASME B1.13M (6h–6G)
Form OptionsHex, square, round, threaded forms and other shapes as per gauge
Head TypesHex, square, round, flat, hex-flange, T-head, triangular and customized heads
Neck StylesKnurled, square, hex, oval, triangular and other special neck types
Surface FinishesZinc, Xylan, Teflon, black oxide, cadmium, galvanization, or coatings as specified
Manufacturing ProcessWire drawing, cold forming, threading/tapping, heat treatment, coating, inspection, and final packing

Equivalents of Stainless Steel Bolts

British (BS)FrenchGerman (EN)ItalianJapanese (SUS)SwedishUSA (AISI / SS)
301S21Z12CN17.081.4310X12CrNi17-07SUS30114 23 31301
304S31–––SUS30214 23 32302
304S15 / 304S16Z8CN18.091.4301X5CrNi18-10SUS30414 23 33304
304S11Z2CN18.101.4306X2CrNi18-11SUS304L14 23 52304L
305S19Z8CN18.12–X8CrNi18-12SUS305–305
309S24Z15CN24.13–X16CrNi23-14SUS309–309
310S24Z12CN25.201.4845Z22CrNi25-20SUS310S14 23 61310
315S16––––14 23 40–
316S31 / 316S33Z6CND17.111.4401X5CrNiMo17-12-2SUS31614 23 43 / 14 23 47316
316S11 / 316S13Z2CND17.121.4404 / 1.4435X2CrNiMo17-12SUS316L14 23 53 / 14 23 48316L
317S12Z2CND19.151.4435X2CrNiMo18-16SUS317L14 23 67317L
317S16–1.4436–SUS31714 23 66317
320S31 / 320S33Z8CND17.121.4571 / 1.4573––14 23 50–
321S31Z6CNT18.121.4541X6CrNiTi18-11SUS32114 23 37321
347S31Z6CNNb18.111.4558X6CrNiNb18-11 / X8CrNiNb18-11SUS34714 23 38347
403S17Z6C131.4000X6Cr13SUS40314 23 01403
405S17Z6CA131.4002Z6CrA1-13SUS405–405
409S19–1.4512–––409
430S17Z8C171.4016X8Cr17SUS43014 23 20430
434S17Z8CD17.011.4113X8CrMo17SUS43414 23 25434
410S21Z12C131.4006 / 1.4024X12Cr13SUS41013 23 02410
410S45Z30C13–X30Cr13SUS420J14 23 04420

Chemical Composition of Stainless Steel Bolt

GradeISO ClassCarbon (C) %Manganese (Mn) %Chromium (Cr) %Nickel (Ni) %Molybdenum (Mo) %Stabilizing Element
304 / 304LA20.08 / 0.032.018.0–20.08.0–10.5––
310 / 310S–0.082.024.0–26.019.0–22.0––
316 / 316LA40.08 / 0.032.016.0–18.010.0–14.02.0–3.0–
317 / 317L–0.08 / 0.032.018.0–20.011.0–15.03.0–4.0–
321A30.082.017.0–19.09.0–12.0–Ti ≥ 5 × C
347 / 347HA30.082.017.0–19.09.0–13.0–Nb ≥ 10 × C
904L–0.02 max2.0 max19.0–23.023.0–28.04.0–5.0Cu 1.0–2.0%

Mechanical Properties of SS Bolts

Bolt GradeProperty ClassMinimum Tensile Strength (Rm)Minimum Yield Strength (Rp0.2)Minimum Elongation After Fracture*Applicable Diameter
A2 / A4 Stainless Steel Bolts70700 MPa450 MPa0.4d≤ M20
A2 / A4 Stainless Steel Bolts70600 MPa340 MPa0.4d> M20 to M39
A2 / A4 Stainless Steel Bolts80800 MPa600 MPa0.3d≤ M20
A2 / A4 Stainless Steel Bolts80600 MPa440 MPa0.3d> M20 to M39

Stainless Steel Fastener Identification Markings

Many stainless steel fasteners are marked according to ISO 3506 property classes.

MarkingMaterial Grade
A2-70304 Stainless Steel
A2-80High Strength 304 Stainless Steel
A4-70316 Stainless Steel
A4-80High Strength 316 Stainless Steel

Markings help users identify material grade and mechanical property class during installation and maintenance.

Stainless Steel Bolt Torque Values (Small Sizes – Inch-Pounds)

Bolt Size18-8 SS (in-lbs)316 SS (in-lbs)Silicon Bronze (in-lbs)Monel (in-lbs)Brass (in-lbs)Aluminum 2024-T4 (in-lbs)
4-405.25.54.85.34.32.9
4-486.66.96.16.75.43.6
5-407.78.17.17.86.34.2
5-449.49.88.79.67.75.1
6-329.610.18.99.87.95.3
6-4012.112.711.212.39.96.6
8-3219.820.718.420.216.210.8
8-3622.023.020.422.418.012.0
10-2422.823.821.225.918.613.8
10-3231.733.129.334.925.919.2
1/4-2075.278.868.885.361.545.6
1/4-289499871067757
5/16-1813213812314910780
5/16-2414214713116011686
3/8-16236247219266192143
3/8-24259271240294212157
7/16-14376393349427317228
7/16-20400418371451327242

Stainless Steel Bolt Torque Values (Large Sizes – Foot-Pounds)

Bolt Size18-8 SS (ft-lbs)316 SS (ft-lbs)Silicon Bronze (ft-lbs)Monel (ft-lbs)Brass (ft-lbs)Aluminum 2024-T4 (ft-lbs)
1/2-1343454048.735.226
1/2-20454742513727
9/16-12565953654734
9/16-18626558715138
5/8-119296861117660
5/8-18103108961238567
3/4-1012713111815310482
3/4-1612412911514910280
7/8-9194202178231159124
7/8-14193201177230158124
1-8286299265344235184
1-14259270240311212166

Preventing Thread Galling in Stainless Steel Fasteners

Stainless steel fasteners are susceptible to thread galling when tightened at excessive speed or under high friction conditions.

Best practices include:

  • Use nickel-based or molybdenum-based anti-seize compounds.
  • Avoid impact tools whenever possible.
  • Tighten at a controlled speed.
  • Keep threads clean and free from contamination.
  • Use calibrated torque tools.

ISO Standard for Stainless Steel Bolts

Product TypeDIN StandardISO StandardASME / ANSIScope
HCS (Hex Cap Screws)DIN 931ISO 4014ASME B18.2.3.1MPartially Threaded
HCS (Hex Cap Screws)DIN 933ISO 4017—Fully Threaded
HCS (Fine Thread)DIN 960ISO 8765—Partially Threaded (Fine)
HCS (Fine Thread)DIN 961ISO 8676—Fully Threaded (Fine)
NutsDIN 934ISO 4032ASME B18.2.4.1M (Style 1)Classes 6, 8 & 10
SHCS (Socket Head Cap Screws)DIN 912ISO 4762ASME B18.3.1Hex Socket Head
BHSHCS (Button Head Socket Cap Screws)—ISO 7380ASME B18.3.4MButton Head Socket
FHSCS (Flat Head / Countersunk Socket Cap Screws)—ISO 10642ASME B18.3.5Countersunk Socket Head
Stud Bolts / Threaded RodsDIN 976-1ISO 898-1*ASME B18.31.2Fully Threaded Studs and Threaded Rods

Stainless Steel 904L Bolts Price

The price of Stainless Steel 904L Bolts depends on factors such as bolt size, thread type, dimensions, manufacturing standard, quantity ordered, surface finish, testing requirements, and delivery destination. Since nickel and molybdenum prices vary, the cost of 904L bolts changes with market conditions.

ProductApproximate FOB Price*
Stainless Steel 904L Hex BoltsUSD 8–18 per kg
Stainless Steel 904L Hex Head BoltsUSD 8–18 per kg
Stainless Steel 904L Stud BoltsUSD 9–20 per kg
Stainless Steel 904L Socket Head Cap BoltsUSD 10–22 per kg
Stainless Steel 904L Anchor BoltsUSD 10–22 per kg

*Prices are indicative only and may vary depending on raw material prices, quantity, specifications, testing requirements, and shipping destination.

Applications of Stainless Steel Bolts

Stainless steel bolts are widely used in environments where strength, corrosion resistance, and long service life are essential. Common applications include:

  • Marine & Offshore: Shipbuilding, docks, and coastal structures exposed to saltwater.
  • Water & Wastewater Systems: Desalination plants, pumping stations, and treatment facilities.
  • Industrial Equipment: Pumps, valves, chemical processing units, and machinery.
  • Construction & Infrastructure: Bridges, pipelines, and large structural projects.
  • Petrochemical Plants: Refineries, reactors, and chemical storage systems.
  • Renewable Energy: Wind turbines, solar structures, and utility projects.