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Alloy 20 (Carpenter 20Cb-3) Washers Manufacturer & Exporter in India

Explore Alloy 20 (Carpenter 20Cb-3) Washers 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 Alloy 20 (Carpenter 20Cb-3) Washers?

Alloy 20 (Carpenter 20Cb-3) washers are high-performance austenitic stainless steel flat, spring, and lock washers manufactured from UNS N08020 bar or plate, conforming to ASTM B473 and ASTM B462. Designed for exceptional resistance to sulfuric acid, chloride stress corrosion cracking, and pitting, Alloy 20 washers are widely specified in chemical processing, pharmaceutical, and food industries where standard stainless steels fail.

With a balanced composition of nickel, chromium, molybdenum, and copper, Alloy 20 washers provide superior corrosion resistance in aggressive environments, including hot concentrated acids and chloride-bearing solutions. They are the preferred choice for bolted flange joints, vessel closures, and equipment assemblies exposed to harsh chemical media.

Quick Specifications

MaterialAlloy 20 (Carpenter 20Cb-3)
UNS NumberN08020
DIN Number2.4660
Material StandardASTM B473 / ASTM B462
Washer Standard (Metric)DIN 125 / DIN 127 / DIN 9021
Washer Standard (Inch)ASME B18.22.1
TypeFlat, Spring, Lock, Tab, Belleville
Size RangeM3-M100 / 1/8"-4"
HardnessMax 217 HB
Tensile Strength551 MPa (80 ksi) min
Yield Strength241 MPa (35 ksi) min
? All washers supplied with full traceability and NABL-accredited laboratory certification. PMI and corrosion test reports available on request.

Complete the Fastener Set

Other Alloy 20 (Carpenter 20Cb-3) Fastener Products Available from RealBolt

RealBolt also manufactures the complete Alloy 20 (Carpenter 20Cb-3) fastener range — Alloy 20 (Carpenter 20Cb-3) Bolts, Alloy 20 (Carpenter 20Cb-3) Nuts, Alloy 20 (Carpenter 20Cb-3) Screws, Alloy 20 (Carpenter 20Cb-3) Studs, Alloy 20 (Carpenter 20Cb-3) Threaded Rods — from certified bar stock per ASTM with full EN 10204 MTC 3.1/3.2 documentation and fast Mumbai dispatch.
Alloy 20 (Carpenter 20Cb-3) Bolts
Alloy 20 (Carpenter 20Cb-3) Nuts
Alloy 20 (Carpenter 20Cb-3) Screws
Alloy 20 (Carpenter 20Cb-3) Studs
Alloy 20 (Carpenter 20Cb-3) Threaded Rods

Technical Data

Alloy 20 (Carpenter 20Cb-3) Washers Dimensions, Sizes & Thread Standards

Alloy 20 (Carpenter 20Cb-3) Washers are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 125 (flat), DIN 127 (spring), DIN 9021 (large OD), and ASME B18.22.1. Custom OD/ID and thickness available. Metric and inch sizes supplied to order.

Flat Washer Dimensions - Metric (DIN 125)

Size (M)Inner Dia (mm)Outer Dia (mm)Thickness (mm)
M66.4121.6
M88.4161.6
M1010.5202.0
M1213.0242.5
M1617.0303.0
M2021.0373.0
M2425.0444.0
M3031.0564.0
M3637.0665.0
M4243.0786.0
M4849.0926.0
M5657.01058.0
M6465.01158.0
M7273.013010.0
M8081.014010.0
M100101.018012.0

Dimensional & Material Standards

StandardCoversType
DIN 125Flat washersMetric
DIN 127Spring lock washersMetric
DIN 9021Large OD washersMetric
ASME B18.22.1Plain, lock, and spring washersInch
ISO 7089Flat washersMetric
ISO 7090Chamfered washersMetric
Material StandardRequirement
ASTM B473Bar/plate - UNS N08020
ASTM B462Forged washers
ASTM F468Mechanical properties
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

Alloy 20 Chemical Composition

Alloy 20 (Carpenter 20Cb-3) Washers (UNS N08020) are produced from a niobium-stabilized alloy containing nickel (32–38%), chromium (19–21%), molybdenum (2–3%), and copper (3–4%) per ASTM. Niobium stabilization at 8× minimum carbon content prevents intergranular corrosion in weld zones; the Mo + Cu combination delivers sulfuric acid immunity at all concentrations.

Chemical Composition per ASTM B473

ElementComposition (%)
Nickel (Ni)32.0-38.0
Chromium (Cr)19.0-21.0
Iron (Fe)Balance
Copper (Cu)3.0-4.0
Molybdenum (Mo)2.0-3.0
Manganese (Mn)2.0 max
Silicon (Si)1.0 max
Carbon (C)0.07 max
Niobium (Nb)8xC-1.0
Phosphorus (P)0.045 max
Sulfur (S)0.035 max
? All heats spectro-tested and certified by NABL-accredited laboratory. PMI and corrosion test reports available on request.

Why Alloy 20 (Carpenter 20Cb-3) Alloy Composition Matters for Washers

Cu (3–4%) — Sulfuric Acid Resistance
Copper enhances Alloy 20’s resistance to sulfuric acid, making these washers ideal for flange joints and vessel closures in acid process lines where 316L washers would corrode rapidly.
Mo (2–3%) — Pitting & Crevice Protection
Molybdenum increases resistance to pitting and crevice corrosion under washers and bolt heads, especially in chloride-rich and acidic environments.
Nb Stabilization — Intergranular Attack Prevention
Niobium stabilizes Alloy 20 against sensitization, preventing intergranular corrosion at washer-bearing surfaces after welding or high-temperature service.

Fastener Performance

Alloy 20 (Carpenter 20Cb-3) Washers Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for Alloy 20 (Carpenter 20Cb-3) Washers per ASTM. Alloy 20 (Carpenter 20Cb-3) washers achieve 620 MPa tensile strength, with hardness, yield, and elongation values verified by NABL-accredited testing and reported in the EN 10204 MTC.

Bolt SizeRecommended Washer OD (mm)Recommended Washer Thickness (mm)
M12242.5
M16303.0
M20373.0
M24444.0
M30564.0
M36665.0
M42786.0
M48926.0
?? Installation: Always use Alloy 20 washers with Alloy 20 bolts/nuts for optimal corrosion resistance. Ensure flat, clean surfaces to prevent crevice corrosion under the washer.

Industry Applications

Alloy 20 (Carpenter 20Cb-3) Washers Applications — Industries & End Uses

Alloy 20 (Carpenter 20Cb-3) Washers from RealBolt are specified across sulfuric acid plants, fertilizer production, and pharmaceutical where very good corrosion resistance and 620 MPa tensile strength are required for reliable fastener performance. Click each industry below for detailed application examples.
Alloy 20 washers are the industry standard for flange joints, manway covers, and vessel closures in sulfuric acid, phosphoric acid, and nitric acid process lines. Their copper and molybdenum content ensures long-term resistance to acid attack and pitting, outperforming 316L and 904L washers in aggressive chemical environments.
Used in process piping, reactors, and sanitary equipment where resistance to organic acids, cleaning agents, and chloride stress corrosion cracking is critical. Alloy 20 washers prevent contamination and maintain joint integrity in high-purity applications.
Flat and spring washers for bolted assemblies in reverse osmosis (RO) plants, evaporators, and brine heaters. Alloy 20 resists chloride-induced pitting and crevice corrosion, ensuring leak-free performance in saline and brackish water systems.
Washers for digesters, bleach towers, and chemical recovery systems where exposure to acidic liquors and chlorides demands superior corrosion resistance. Alloy 20 maintains mechanical integrity and prevents joint loosening in cyclic wet/dry conditions.

Alloy 20 (Carpenter 20Cb-3) Washers Standards & International Certifications

Alloy 20 (Carpenter 20Cb-3) Washers 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, PMI (XRF), NACE MR0175/ISO 15156, and NABL-accredited lab reports — available on request for all orders.
Standards
DIN 125A DIN 126 DIN 127 DIN 128 ISO 7089 ISO 7090 ASME B18.21.1 EN ISO 7089 IS 5372 IS 1367
Certifications
ISO 9001:2015NACE MR0175NABL LabPED 2014/68/EUMTC 3.1 / 3.2

Buy Alloy 20 (Carpenter 20Cb-3) Washers from India's Leading Manufacturer — Get a Competitive Quote Today

Partner with RealBolt — India’s leading manufacturer of certified Alloy 20 (Carpenter 20Cb-3) Washers — 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.
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Answers for Buyers

Alloy 20 (Carpenter 20Cb-3) Washers — Frequently Asked Questions

Browse expert answers to common questions about Alloy 20 (Carpenter 20Cb-3) Washers from RealBolt — covering ASTM B473, sulfuric acid resistance, niobium stabilization, available sizes, and EN 10204 3.1 documentation. Contact our technical team directly for project-specific guidance on Alloy 20 (Carpenter 20Cb-3) washers selection and pricing.
Alloy 20 washers are available to DIN 125 (flat), DIN 127 (spring), DIN 9021 (large OD), ISO 7089/7090, and ASME B18.22.1 (inch). Custom OD, ID, and thickness can be supplied to drawing. All washers are manufactured from ASTM B473 or ASTM B462 certified material, with full traceability and EN 10204 3.1/3.2 certification.
Yes, Alloy 20 washers can be used with stainless steel bolts, but for maximum corrosion resistance in aggressive chemical or chloride environments, it is recommended to use Alloy 20 bolts and nuts together. This prevents galvanic corrosion and ensures uniform performance in the joint.
Absolutely. Alloy 20 is specifically designed for sulfuric acid resistance and is the preferred washer material for flange joints, vessel covers, and equipment in sulfuric acid plants. Its copper and molybdenum content provides superior protection against acid attack and pitting.
No formal MOQ for standard sizes (M6-M36) held in stock – we supply from single pieces for urgent maintenance. Custom sizes or special profiles have an MOQ of 10 kg. Large OD or non-standard thickness washers are made to order with competitive lead times.

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