HardwareTools

Stainless Steel Fasteners for the USA and European Markets

The stainless steel fasteners are classified by alloying composition, shape, and finish. The fasteners used in Europe and USA, as well as other regions, must meet specifications in terms of mechanical, chemical, and physical characteristics under specified conditions. Further, they must conform to standards in terms of performance, composition, toxicity, corrosion, resistance, and more.

Generally, the stainless steels are superior engineering materials used for the fabrication of corrosion resistant, high-quality fasteners for a wide range of applications. The alloy, of low carbon and chromium, provides good corrosion resistance, high mechanical strength, and can be customized to provide the desired characteristics.

In addition to the low carbon and chromium, the other alloying elements which can be added to improve the characteristics include aluminum, copper, molybdenum, nickel, niobium, nitrogen, selenium, silicon, sulfur, and titanium. Additional hardening process, surface treatments such as coatings and plating improve the fastener’s properties such as corrosion resistance and appearance and make them suitable for specific applications.

Steel Stainless fasteners for the USA and Europe

The standards in the USA are set by the American Society for Testing Materials (ASTM), while those in Europe are set by the International Standards Organization (ISO). However, most of the physical and chemical properties of the stainless steel fasteners are similar for the corresponding equivalent grades.

Most stainless steel fasteners for the USA and Europe are made from the ASTM 304 (18-8) or DIN/ISO A2, and ASTM 316 or DIN/ISO A4. The 304/A2 grade provides good corrosion resistant protection and is used for most general applications. The acid resistant, 316/A4, is used in more corrosive environments such as marine and chlorine environments where the 304 would be susceptible to corrosion.

In Europe, the grade A2 and A4 are used, with either a property class of 70 or 80, the A refers to the Austenitic Stainless steel while the property class indicates the mechanical properties. The Grade A2 is equivalent to the American standard grade 1.4301 (304), while the A4 is equivalent to 1.4401 (316).

The other less commonly used stainless steel grades for fasteners include 303, 309, 317,321,330, 347, 410, 416, 422, 430, 431, 440, and 501.

Stainless steel type 304 (A2)

The alloy contains conventional carbon, between 18 and 20 percent chromium, and 8-12 percent nickel. It is easy to manufacture and clean. The 304 grade is commonly referred to as 18-8 and is used in wide range environments free of chemicals.

The 304 is used for all kinds of fasteners from small screws to large bolts and nuts.

Stainless steel type 306 (A4)

The 316 alloy has 16-18 percent chromium, 10-14 percent Nickel and 2-3 percent molybdenum. The higher nickel concentration and the addition of molybdenum improve the protection against the crevice or pitting corrosion.

 

Stainless steel 316 has higher corrosion resistance and suited for salty water, marine and chlorine, moist and wet environments, and other applications requiring a higher degree of corrosion resistance. It is, however, more expensive than the 304.

 

Chemical composition for fasteners made of stainless steel 

 

The chemical compositions of the various fastener grades under different standards are shown below.

 

Table 1 Chemical composition for stainless steel fasteners

 

Grade Chemical Composition (% maxima unless stated) Alternative names
C Si Mn P S Cr          Mo Ni        Cu
A1 0.12 1 6.5 0.2 0.15/0.35 16-19 0.7  5-10 1.75-2.25 303S31, 303S42, 1.4305
A2 0.1 1 2 0.05 0.03 15-20 5 8-19 4 304, 394S17 (BS 3111), 1.4301, 1.4567
A3 0.08 1 2 0.045 0.03 17-19 5 9-12 1 321, 1.4541, 347, 1.4550
A4 0.08 1 2 0.045 0.03 16-18.5 2-3 10-15 4 316, 1.4401, 1.4578
A5 0.08 1 2 0.045 0.03 16-18.5 2-3 10.5-14 1 316Ti, 1.4571, 316Cb, 1.4580
C1 0.09-0.15 1 1 0.05 0.03 11.5-14 1  – 410, 1.4006
C3 0.17-0.25 1 1 0.04 0.03 16-18 1.5-2.5 431, 1.4057
C4 0.08-0.15 1 1.5 0.06 0.15-0.35 12-14 0.6 1 416, 1.4005
F1 0.12 1 1 0.04 0.03 15-18 10 1 430, 1.4016, 430Ti, 1.4520 430Cb, 1.4511

Source:  http://www.bssa.org.uk/topics.php?article=1

Table 2: The equivalent European and USA stainless steel fastener grades

European standards USA standards
Steel name Steel number AISI UNS
X10CrN18-8 1.4310 301 S30100
X8CrNi18-9 1.4305 303 S30300
X5CrNi18-10 1.4301 304 S30400
X2CrNi19-11 1.4306 304L S30403
X6CrNi25-20 1.4951 310 S31000
X5CrNiMo17-12-2 1.4401 316 S31600
X2CrNiMo17-12-2 1.4404 316L S31603
X2CrNiMo18-15-4 1.4438 317 S31700
X6CrNiMoNb17-12-2 1.4580 316Cb S31640
X6CrNiMoTi17-12-2 1.4571 316Ti S31635
X6CrNiTi18-10 1.4541 321 S32100
X6CrNiNb18-10 1.4550 347 S34700
X6Cr13 1.4000 410S S41008
X6CrAl13 1.4002 405 S40500
X2CrTi12 1.4512 409 S40900
X12Cr13 1.4006 410 S41000
X12CrS13 1.4005 416 S41600
X20Cr13 1.4021 420 S42000
X6Cr17 1.4016 430 S43000
X17CrNi16-2 1.4057 431 S43100
X2CrNiN23-4 1.4362 (2304) ! S32304
X2CrNiMoN22-5-3 1.4462 (2205) ! S31803

 

NB! Entries in parentheses are common names, not true AISI designations

Source: http://www.twi-global.com/technical-knowledge/faqs/material-faqs/faq-what-are-the-equivalent-european-and-american-standards-for-common-stainless-steels/

The standards for the common types of stainless steel fasteners in Europe and the USA are similar in terms of composition and treatment; however, their naming is different as indicated in table 2 above.

Have any Question or Comment?

Leave a Reply

Your email address will not be published. Required fields are marked *

%d bloggers like this: