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SS 321 Screws Manufacturer & Exporter in India

Explore SS 321 Screws Manufacturer & Exporter in India manufactured for demanding industrial applications with reliable strength, corrosion resistance and compliance with international standards.
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-196

Min Temp

870

Max Temp

🌡

870

Suitable for continuous service up to approximately 870°C under typical operating conditions.

⚡

620

Typical tensile strength around 620 MPa depending on product form and heat treatment.

🛡

Very Good

Very Good corrosion resistance in a wide range of industrial environments.

⚖

8

Typical density is approximately 8.0 g/cm³.

Product Overview

What are SS 321 Screws?

SS 321 screws are austenitic stainless steel fasteners manufactured from stabilized grade 321 (UNS S32100) bar stock, conforming to ASTM A193 and ASTM F593 standards. Alloy 321 is titanium-stabilized, providing superior resistance to intergranular corrosion and carbide precipitation during welding or high-temperature service. These screws are ideal for bolted joints exposed to continuous temperatures up to 870°C, where standard 304/316 grades may fail due to sensitization.

SS 321 screws are widely specified for exhaust manifolds, heat exchangers, and process piping in refineries, chemical plants, and power generation facilities. Their excellent oxidation resistance and mechanical stability make them a preferred choice for high-temperature bolted assemblies.

Quick Specifications

MaterialStainless Steel 321
UNS NumberS32100
DIN Number1.4541
Material StandardASTM A193 / ASTM F593
Screw Standard (Metric)DIN 912 / DIN 933 / ISO 4762
Screw Standard (Inch)ASME B18.3 / ASME B18.6.3
Thread FormISO Metric / UNC / UNF
Diameter RangeM3-M48 / 1/8"-2"
Tensile Strength515 MPa (75 ksi) min
Yield Strength205 MPa (30 ksi) min
HardnessMax 95 HRB / 217 HB
? All material certified by NABL-accredited laboratory. PMI and IGC test reports available on request.

Complete the Fastener Set

Other SS 321 Fastener Products Available from RealBolt

RealBolt also manufactures the complete SS 321 fastener range from certified stainless steel bar stock, including SS 321 Bolts, SS 321 Nuts, SS 321 Washers, SS 321 Studs, and SS 321 Threaded Rods. All SS 321 fastener types are produced to ASTM with full EN 10204 MTC 3.1/3.2 documentation.
SS 321 Bolts
SS 321 Nuts
SS 321 Washers
SS 321 Studs
SS 321 Threaded Rods

Technical Data

SS 321 Screws Dimensions, Sizes & Thread Standards

SS 321 Screws are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 912 (socket head cap), DIN 933 (hex head full thread), ISO 4762, and ASME B18.3. Custom lengths available in 5mm increments. Inch sizes per ASME B18.6.3. All SS 321 screws dimensions conform to applicable DIN, ISO, and ASME B18 standards.

Socket Head Cap Screw Dimensions - Metric (DIN 912 / ISO 4762)

Size (M)Pitch (mm)Head Dia (mm)Head Ht (mm)Hex Socket (mm)Min L (mm)Max L (mm)
M30.55.53.02.5650
M40.77.04.03.0860
M50.88.55.04.01070
M61.010.06.05.01280
M81.2513.08.06.016100
M101.516.010.08.020120
M121.7518.012.010.025150
M162.024.016.014.030200
M202.530.020.017.035250
M243.036.024.019.040300
M303.545.030.022.050400
M364.054.036.027.060500
M424.563.042.032.070600
M485.072.048.036.080700

Dimensional & Material Standards

StandardCoversThread
DIN 912Socket head cap screwsMetric
DIN 933Hex head screws, full threadMetric
ISO 4762Socket head cap screwsMetric
ASME B18.3Socket cap screwsUNC/UNF
ASME B18.6.3Machine screwsUNC/UNF
Material StandardRequirement
ASTM A193Bolting for high temp/pressure
ASTM F593Stainless steel fasteners
ASTM A276Bar/rod - UNS S32100
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

SS 321 Chemical Composition

SS 321 Screws are manufactured from an iron-chromium-nickel alloy with chromium (16–26%), nickel (8–28%), and grade-specific molybdenum additions per ASTM and ASTM A193/A194. Chromium content governs the self-healing passive oxide film; molybdenum (2–6%) enhances chloride pitting resistance; and carbon content determines sensitization risk in welded assemblies.

Chemical Composition per ASTM A276

ElementComposition (%)
Chromium (Cr)17.0-19.0
Nickel (Ni)9.0-12.0
Carbon (C)0.08 max
Manganese (Mn)2.00 max
Silicon (Si)0.75 max
Phosphorus (P)0.045 max
Sulfur (S)0.030 max
Titanium (Ti)5xC min, 0.70 max
Iron (Fe)Balance
? All heats verified by NABL-accredited spectrometry. IGC and PMI reports available on request.

Why SS 321 Alloy Composition Matters for Screws

Titanium Stabilization — Prevents Sensitization
Titanium in SS 321 binds carbon, preventing chromium carbide precipitation at grain boundaries during welding or high-temperature exposure. This ensures screws retain corrosion resistance even after fabrication or service at 450–850°C.
High Chromium & Nickel — Oxidation Resistance
The 17–19% chromium and 9–12% nickel content provide excellent resistance to oxidation and scaling up to 870°C, making SS 321 screws ideal for exhaust, furnace, and heat exchanger applications.
Low Carbon — Maintains Ductility
Low carbon content ensures good ductility and toughness, reducing the risk of embrittlement in high-temperature bolted joints.

Fastener Performance

SS 321 Screws Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for SS 321 Screws per ASTM. SS 321 screws achieve 620 MPa tensile strength, with hardness, yield, and elongation values verified by NABL-accredited testing and reported in the EN 10204 MTC.

Screw SizeDry (Nm)Lubricated (Nm)Clamp Load (kN)
M61087.5
M8252012.5
M10504020.5
M12856829.5
M1621016859.5
M2042033693.5
M24720576135.5
?? Anti-galling: Use molybdenum-based or PTFE anti-seize. Lubricated values assume K=0.16. Avoid over-tightening to prevent thread galling in stainless steel.

Industry Applications

SS 321 Screws Applications — Industries & End Uses

SS 321 Screws from RealBolt are specified across food and dairy, pharmaceutical, marine, chemical processing, and oil and gas where very good corrosion resistance and 620 MPa tensile strength are required for reliable fastener performance. Click each industry below for detailed application examples.
SS 321 screws are widely used for bolting flanges, pipe supports, and expansion joints in refinery and petrochemical piping systems. Their resistance to intergranular corrosion and high-temperature scaling makes them ideal for process lines carrying hot hydrocarbons, steam, or corrosive gases.
Socket head and hex head SS 321 screws are specified for fastening exhaust manifolds, heat exchanger tube sheets, and ductwork in power plants and chemical processing units. Their stability at elevated temperatures prevents loosening and scaling in cyclic thermal environments.
SS 321 screws are used in the assembly of furnace linings, kiln doors, and burner mounts, where resistance to oxidation and thermal fatigue is critical for long-term reliability.
SS 321 screws are chosen for high-temperature food processing and pharmaceutical drying equipment, where both corrosion resistance and non-contamination are essential.

SS 321 Screws Standards & International Certifications

SS 321 Screws from RealBolt Engineering Industries are manufactured to internationally recognised fastener dimensional standards covering thread form, tolerances, strength grades, and quality requirements. Every batch ships with EN 10204 MTC 3.1/3.2, IS 12427 compliance, ISO 3506 material certification, NACE MR0175, and PMI (XRF) reports — available on request for all orders.
Standards
DIN 84 DIN 85 DIN 912 DIN 913 DIN 914 DIN 915 DIN 916 DIN 6912 DIN 7984 DIN 7985 DIN 7991 DIN 965 DIN 966 DIN 967 ISO 4762 ISO 10642 ISO 14579 ASME B18.3 ASME B18.6.3 EN ISO 4762 IS 1363 IS 1367 IS 12427 SAE J933
Certifications
ISO 9001:2015PED 2014/68/EUNABL LabMTC 3.1 / 3.2

Buy SS 321 Screws from India's Leading Manufacturer — Get a Competitive Quote Today

Partner with RealBolt — India’s leading manufacturer of certified SS 321 Screws — for competitive pricing, EN 10204 MTC 3.1/3.2 documentation, and fast Mumbai dispatch. Standard sizes are ex-stock; custom dimensions accepted with 2–3 week lead time. Request your quote today.
022-6743-7972
+91 90226 36025
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Answers for Buyers

SS 321 Screws — Frequently Asked Questions

Browse expert answers to common questions about SS 321 Screws from RealBolt — covering ASTM A193/A194 grades, chloride resistance, temperature limits, sensitization, sizes, and MTC documentation. Contact our technical team directly for project-specific guidance on SS 321 screws selection and pricing.
SS 321 screws are available to DIN 912 (socket head cap), DIN 933 (hex head full thread), ISO 4762, and ASME B18.3 (inch socket cap). Machine screws are supplied per ASME B18.6.3. Custom thread forms (UNC, UNF, BSW) and non-standard lengths are available with short lead times.
Use a molybdenum-based or PTFE anti-seize compound (such as Molykote 1000 or Loctite LB 8014) on SS 321 screw threads and under heads to prevent galling. Avoid copper-based anti-seize in high-temperature or food/pharma applications. Reduce torque by 20% when lubricated.
Yes – SS 321 screws are specifically designed for high-temperature service up to 870°C. Their titanium stabilization prevents intergranular corrosion and scaling, making them ideal for exhaust manifolds, furnace linings, and heat exchanger assemblies.
No MOQ for standard sizes (M6-M24) in stock – we supply from single pieces for urgent maintenance. Custom sizes or non-standard threads may require a 10 kg minimum. Bulk price breaks at 100, 500, and 1000 pieces.

Industrial Cities We Serve:

  • Ahmedabad
  • Aurangabad
  • Bengaluru
  • Chennai
  • Coimbatore
  • Faridabad
  • Gandhidham
  • Greater Noida
  • Gurugram
  • Hazira
  • Hosur
  • Hyderabad
  • Jamnagar
  • Jamshedpur
  • Ludhiana
  • Mumbai
  • Mundra
  • Mysuru
  • Nagpur
  • Nashik
  • Navi Mumbai
  • Noida
  • Pune
  • Rajkot
  • Sanand
  • Surat
  • Thane
  • Tiruppur
  • Vadodara
  • Visakhapatnam

Countries We Export To:

  • US
  • Canada
  • Mexico
  • Germany
  • UK
  • France
  • Italy
  • Spain
  • Netherlands
  • Belgium
  • Poland
  • Sweden
  • Norway
  • Denmark
  • Turkey
  • UAE
  • Saudi Arabia
  • Qatar
  • Oman
  • Kuwait
  • Bahrain
  • South Africa
  • Egypt
  • Nigeria
  • Australia
  • New Zealand
  • Singapore
  • Malaysia
  • Indonesia
  • Thailand
  • Vietnam
  • South Korea
  • Japan
  • Brazil