STAINLESS STEEL FASTENERS
Introduction
Stainless steel fasteners are specified to BS EN ISO 3506. Part 1 covers bolts, screws and studs. Part 2 covers nuts. These specifications replaced BS 6105. The latest edition was issued in 2020 and now includes 6% Mo Austenitic stainless steels and Duplex stainless steels, along with a new ‘100’ property class for these steels, (and for the previous ‘A4’ and ‘A5’ fastener classifications).
Chemical composition for austenitic stainless steel fasteners
The chemical compositions of the various fastener grades are shown in Table 1. The approximate equivalent grades in other systems are shown for reference. The composition ranges are much wider in this standard than in the standards for the feedstock product, usually bar.
Table 1 Chemical composition for stainless steel fasteners
| Grade | Chemical Composition1 (% maxima unless stated) | Notes | Alternative names | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C | Si | Mn | P | S | Cr | Mo | Ni | Cu | N | |||
| A1 | 0.12 | 1.00 | 6.5 | 0.020 | 0.15/0.35 | 16.0-19.0 | 0.70 | 5.0-10.0 | 1.75-2.25 | – | 2 3 4 | 303S31, 303S42, 1.4305 |
| A2 | 0.10 | 1.00 | 2.00 | 0.050 | 0.030 | 15.0-20.0 | –5 | 8.0-19.0 | 4.0 | – | 6 7 | 304, 394S17 (BS 3111), 1.4301, 1.4567 |
| A3 | 0.08 | 1.00 | 2.00 | 0.045 | 0.030 | 17.0-19.0 | –5 | 9.0-12.0 | 1.00 | – | 8 | 321, 1.4541, 347, 1.4550 |
| A4 | 0.08 | 1.00 | 2.00 | 0.045 | 0.030 | 16.0-18.5 | 2.00-3.00 | 10.0-15.0 | 4.0 | – | 7 9 | 316, 1.4401, 1.4578 |
| A5 | 0.08 | 1.00 | 2.00 | 0.045 | 0.030 | 16.0-18.5 | 2.00-3.00 | 10.5-14.00 | 1.00 | – | 8 9 | 316Ti, 1.4571, 316Cb, 1.4580 |
| A8 | 0.030 | 1.00 | 2.00 | 0.040 | 0.030 | 19.0-22.0 | 6.0-7.0 | 17.5-26.0 | 1.50 | – | – | 6% Mo, 1.4547, 1.4529 |
| C1 | 0.09-0.15 | 1.00 | 1.00 | 0.050 | 0.030 | 11.5-14.0 | – | 1.00 | – | – | 9 | 410, 1.4006 |
| C3 | 0.17-0.25 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0-18.0 | – | 1.50-2.50 | – | – | 431, 1.4057 | |
| C4 | 0.08-0.15 | 1.00 | 1.50 | 0.060 | 0.15-0.35 | 12.0-14.0 | 0.60 | 1.00 | – | – | 2 9 | 416, 1.4005 |
| F1 | 0.08 | 1.00 | 1.00 | 0.040 | 0.030 | 15.0-18.0 | –10 | 1.00 | – | – | 11 12 | 430, 1.4016, 430Ti, 1.4520 430Cb, 1.4511 |
| D2 | 0.040 | 1.00 | 6.00 | 0.040 | 0.030 | 19.0-24.0 | 0.10-1.00 | 1.50-5.5 | 3.00 | 0.05-0.20 | 13 | Lean Duplex, DX 2202 1.4062, 1.4162 LDX 2101 |
| D4 | 0.040 | 1.00 | 6.00 | 0.040 | 0.030 | 21.0-25.0 | 0.10-2.00 | 1.00-5.5 | 3.00 | 0.05-0.30 | 14 | 2304 1.4362 |
| D6 | 0.030 | 1.00 | 2.00 | 0.040 | 0.015 | 21.0-23.0 | 2.50-3.5 | 4.5-6.5 | – | 0.08-0.35 | – | 2205 1.4462 |
| D8 | 0.030 | 1.00 | 2.00 | 0.035 | 0.015 | 24.0-26.0 | 3.00-4.5 | 6.0-8.0 | 2.50 | 0.20-0.35 | 15 | Zeron 100 1.4501, Ferrinox 255 1.4507 |
Notes
- Values are maximum unless otherwise indicated.
- Sulphur may be replaced by selenium.
- If the nickel content is below 8 %, the minimum manganese content shall be 5 %.
- There is no minimum limit to the copper content provided that the nickel content is greater than 8 %.
- Molybdenum may be present at the discretion of the manufacturer. However, if for some applications limiting of the molybdenum content is essential, this shall be stated at the time of ordering by the purchaser.
- If the chromium content is below 17 %, the minimum nickel content should be 12 %.
- For austenitic stainless steels having a maximum carbon content of 0,03 %, nitrogen may be present to a maximum of 0,22 %.
- Shall contain titanium ≥ 5 × C up to 0,8 % maximum for stabilisation and be marked appropriately in accordance with this table, or shall contain niobium, (columbium), and/or tantalum ≥ 10 × C up to 1,0 % maximum for stabilisation and be marked appropriately in accordance with this table
- At the discretion of the manufacturer the carbon content may be higher, where required in order to obtain the specified mechanical properties at larger diameters, but shall not exceed 0,12 % for austenitic steels.
- Molybdenum may be present at the discretion of the manufacturer.
- May contain titanium ≥ 5 × C up to 0,8 % maximum.
- May contain niobium, (columbium), and/or tantalum ≥ 10 × C up to 1 % maximum.
- Cr + 3.3Mo + 16N < or = 24.0 . This formula is used solely for the purpose of classifying duplex steels, it is not intended to be used as a selection criterion for corrosion resistance.
- 24.0 < Cr + 3.3Mo +16N . This formula is used solely for the purpose of classifying duplex steels, it is not intended to be used as a selection criterion for corrosion resistance.
- W < or = 1.00
Mechanical properties for stainless steel fasteners
There are now four ‘property classes’ which are assigned selectively across the various austenitic stainless steel fastener grades now included in the standard. Table 2 shows the 0.2% proof stress, tensile strength and elongation values for each of these property classes.
Table 2 Mechanical properties for austenitic stainless steel bolts, screws and studs
A8
| Steel Group | Steel Grade | Property Class | Tensile Strength Rm1 min MPa | 0.2% Proof Stress Rp0.21 min MPa | Elongation A2 min mm |
| Austenitic | A1, A2, A3 | 50 | 500 | 210 | 0.6d |
| 70 | 700 | 450 | 0.4d | ||
| 80 | 800 | 600 | 0.3d | ||
| A4,A5, | |||||
| 70 | 700 | 450 | 0.4d | ||
| 80 | 800 | 600 | 0.3d | ||
| 100 | 1000 | 800 | 0.2d | ||
| 70 | 700 | 450 | 0.4d | ||
| 80 | 800 | 600 | 0.3d | ||
| 100 | 1000 | 800 | 0.2d |
Notes
- The tensile stress is calculated on the stress area
- To be determined on the actual screw length and not on a prepared test piece.
This latest revision has removed the restrictions on the size of fastener (M24) for which the properties in table 2 can be guaranteed. However, there is a general clause which says that the standard is only applicable up to 39 mm diameter. Above that, the standard can still be used provided all parties agree that the properties can be achieved. The effect of these changes is to increase the maximum diameter on which the class 70 and 80 properties can be specified without discussion from 24 to 39 mm. This reflects the conservative nature of the previous 24 mm limit. Indeed, class 70 and 80 properties are available above 39 mm but this must always be discussed with the supplier.
Property class 50 represents the steel in the annealed condition.
The most common and readily available supply condition is property class 70, which represents a ‘cold drawn’ for the bar stock from which the fasteners are made.
Property class 80 is based on severely hard cold drawn bar.
Property class 100 condition, i.e. with a minimum tensile strength of 1000 MPa. is now part of the official standard.
All tensile stress values are calculated and reported in terms of the nominal tensile stress area of the thread.
The elongation measurement is determined on the actual bolt or screw length and not on a prepared test piece. It is expressed in millimetres (mm) of extension and not as percentage elongation, i.e. A = (L2 – L1)
(where L1 = original length and L2 = length after fracture)
d = nominal diameter of bolt, screw or stud
There are three ‘property classes’ which are assigned to the Duplex stainless steel fastener grades now included in the standard. Table 3 shows the 0.2% proof stress, tensile strength and elongation values for each of these property classes.
Table 3 Mechanical properties for Duplex stainless steel bolts, screws and studs
| Steel Group | Steel Grade | Property Class | Tensile Strength Rm1 min MPa | 0.2% Proof Stress Rp0.21 min MPa | Elongation A2 min mm |
| Duplex | D2, D4, D6, D8 | 70 | 700 | 450 | 0.4d |
| 80 | 800 | 600 | 0.3d | ||
| 100 | 1000 | 800 | 0.2d |
Notes
- The tensile stress is calculated on the stress area
- To be determined on the actual screw length and not on a prepared test piece.
This latest revision has removed the restrictions on the size of fastener, (M24), for which the properties in table 2 can be guaranteed. However, there is a general clause which says that the standard is only applicable up to 39 mm diameter. Above that, the standard can still be used provided all parties agree that the properties can be achieved. The effect of these changes is to increase the maximum diameter on which the class 70 and 80 properties can be specified without discussion from 24 to 39 mm. This reflects the conservative nature of the previous 24 mm limit. Indeed, class 70 and 80 properties are available above 39 mm but this must always be discussed with the supplier.
Duplex stainless steels are intrinsically stronger than standard austenitic stainless steels, so higher strengths can be achieved at lower levels of cold work, and hence there is no class ’50’, for these steels.
Property class 80 is based on cold drawn bar.
Property class 100 condition, i.e. with a minimum tensile strength of 1000 MPa. is now part of the official standard.
All tensile stress values are calculated and reported in terms of the nominal tensile stress area of the thread.
The elongation measurement is determined on the actual bolt or screw length and not on a prepared test piece. It is expressed in millimetres, (mm), of extension and not as percentage elongation, i.e. A = (L2 – L1),
(where L1 = original length and L2 = length after fracture)
d = nominal diameter of bolt, screw or stud
Table 4 — Mechanical properties for bolts, screws and studs – Martensitic and ferritic steel grades
| Steel group | Steel grade | Property class | Tensile Strength Rm1 min MPa | 0.2% Proof Stress Rp0.21 min MPa | Elongation A2 min mm | Hardness | ||
| HB | HRC | HV | ||||||
| Martensitic | C1 | 50 | 500 | 250 | 0.2 d | 147/209 | 155/220 | |
| 70 | 700 | 410 | 0.2 d | 209/314 | 20/34 | 220/330 | ||
| 1103 | 1100 | 820 | 0.2 d | – | 36/45 | 350/440 | ||
| C3 | 80 | 800 | 640 | 0.2 d | 228/323 | 21/35 | 240/340 | |
| C4 | 50 | 500 | 250 | 0.2 d | 147/209 | – | 155/220 | |
| 70 | 700 | 410 | 0.2 d | 209/314 | 20/34 | 220/330 | ||
| Ferritic | F14 | 45 | 450 | 250 | 0.2 d | 128/209 | – | 135/220 |
| 60 | 600 | 410 | 0.2 d | 171/271 | – | 180/285 |
- The tensile stress is calculated on the stress area
- To be determined on the actual screw length and not on a prepared test piece
- Hardened and tempered at a minimum tempering temperature of 275 °C
- Nominal thread diameter d ≤ 24 mm
The New Pressure Equipment Directive (PED)
The Pressure Equipment Directive (PED) 97/23/EC is a fundamental piece of European legislation relating to the safety of pressure equipment throughout Europe. Now 17 years old, it will be replaced by the new Directive 2014/68/EU.
The change will implement alignment with the New Legislative Framework which aims to streamline and simplify the rules for putting pressure equipment on the market in the face of increasing competition from fraudulently certified equipment.
The new fluid classification (2014/68/EU) which is part of the New Directive came into force in June 2015, and the remaining changes will come into force subject to enactment into UK law in July 2016.
We plan to support you through this transition, and will provide you with guidelines and useful information to help make this as smooth as possible.
Inspection & Approval Certificates : C/W Certificate (Calibration Works Certificate) EN 10204 3.1 / DIN 50049 3.1 / ISO 10474 3.1 Mill Test Certificate,
ISI Mark, BIS Certified, NACE HIC TM-0284 / NACE MR-0103 / NACE MR-0175 / ISO 15166, CE Marked, European Pressure Equipment Directive
PED-2014/68/EU, AD-2000-WO, ASME Boiler & Pressure Vessel Code Section-II Part A Edition 2019, API 6A (American Petroleum Institute),
with EN 10204 3.2 Certificate duly Certified & Approved by IBR (Indian Boiler Regulations), LR Class (Lloyd’s Register), GL (Germanischer Lloyd),
BV (Bureau Veritas), DNV (Det Norske Veritas), ABS Class (American Bureau of Shipping), SGS, TUV, RINA, IR Class (Indian Register of Shipping),
NORSOK Approved Standard M-630, M-650 Rev.3
If you have any requirement of above items, please feel free to contact us
Regards,
CONTACT PERSON :
MUKESH SHAH
Director
Mobile No. 0091 – 9820292499
Email – marketing@rolexmetals.com
ROLEX METAL DISTRIBUTORS
57-A Khatargalli
Thakurdwar
Mumbai – 400 002 India
0091-22-23858802
0091-22-23823963
0091-22-23898724
marketing@rolexmetals.com
www.rolexmetals.com
CHAIRMAN – chairman@rolexmetals.com
MANAGING DIRECTOR – managingdirector@rolexmetals.com
TECHNICAL DIRECTOR – technicaldirector@rolexmetals.com
SALES DIRECTOR – salesdirector@rolexmetals.com
COMMERCIAL DIRECTOR – commercialdirector@rolexmetals.com
COMMERCIAL MANAGER – commercial@rolexmetals.com
GENERAL MANAGER – generalmanager@rolexmetals.com
SALES MANAGER – salesmanager@rolexmetals.com
PURCHASE MANAGER – purchasemanager@rolexmetals.com
TECHNICAL MANAGER – technical@rolexmetals.com
WORKS MANAGER – worksmanager@rolexmetals.com
STORES MANAGER – stores@rolexmetals.com
WAREHOUSE MANAGER – warehouse@rolexmetals.com
SALES DOMESTIC – salesdomestic@rolexmetals.com
SALES INTERNATIONAL – salesinternational@rolexmetals.com
SALES GENERAL – sales@rolexmetals.com
PURCHASE GENERAL – purchase@rolexmetals.com
FINANCE MANAGER – finance@rolexmetals.com
ACCOUNTS MANAGER – accounts@rolexmetals.com
GENERAL INFORMATION – info@rolexmetals.com
EXPORT MANAGER – export@rolexmetals.com
IMPORT MANAGER – import@rolexmetals.com
AIR EXPORT – airexport@rolexmetals.com
SEA EXPORT – seaexport@rolexmetals.com
CUSTOMS – customs@rolexmetals.com
AIR FREIGHT – airfreight@rolexmetals.com
SEA FREIGHT – seafreight@rolexmetals.com
DESPATCH – despatch@rolexmetals.com
INSPECTION – inspection@rolexmetals.com
LOGISTICS – logistics@rolexmetals.com
TRANSPORT – transport@rolexmetals.com
KALAMBOLI WAREHOUSE – kalamboli@rolexmetals.com
TALOJA WAREHOUSE – taloja@rolexmetals.com
KHOPOLI WAREHOUSE – khopoli@rolexmetals.com
NHAVA SHEVA WAREHOUSE – nhavasheva@rolexmetals.com
KANDLA WAREHOUSE – kandla@rolexmetals.com
MUMBAI WAREHOUSE – mumbai@rolexmetals.com
STOCKYARD – stockyard@rolexmetals.com
SERVICE – service@rolexmetals.com
SUPPORT – support@rolexmetals.com
RECRUITMENT – career@rolexmetals.com
WEBMASTER – webmaster@rolexmetals.com
CUSTOMER CARE – customercare@rolexmetals.com