Specifying stainless steel for spring applications

Introduction

European standards now cover both strip and wire products for springs. BSEN 10151:2002 applies to strip and replaces BS5770 part 4:1981, which is now withdrawn. BSEN 10272-3:2001 applies to wire and replaces BS2056:1981. Both standards use the European steel grade number system, most of which are also shown in BSEN 10088-1

BSEN 10151 stainless steel strip for springs

BSEN 10151 was published in 2002 and replaced BS5770 part 4 (1981), which is now withdrawn. It contains 10 grades, one ferritic, three martensitics, one precipitation hardening and five austenitic. With the exception of austenitic grade 1.4369 (X11CrNiMnN19-8-6), the grade compositions are covered by BS EN 10088-2. The composition of grade 1.4369 has been designed to keep the steel non-magnetic in all conditions. The BSEN 10151 has a more comprehensive scope than BS5770:4.

BSEN 10151 grade 1.4310 is the alternative to BS5770 grade 301S21, 1.4301 the alternative to 302S25 and 1.4401 the alternative to 316S16 in the austenitic types. Grades 1.4021 and 1.4028 are the BSEN 10151 alternatives to martensitic BS5770, 420S29 and 420S45 grades.

The other main difference between the standards is the way in which the 'spring temper' is specified. BSEN 10151 uses tensile strength ranges, rather than the Vickers hardness 'conditions' of BS5770:4. (TR230, TR280, TR330, TR380 etc depending on grade)

BSEN 10151 grades and delivery conditions

The compositions of all the grades are shown below.
Values are maxima, unless there is a range stated.

Steel name Number C Si Mn P S N Cr Mo Ni Others
X6Cr17 1.4016 0.08 1.00 1.00 0.040 0.015 - 16.0/18.0 - - -
X20Cr13 1.4021 0.16/0.25 1.00 1.50 0.040 0.015 - 12.0/14.0 - - -
X30Cr13 1.4028 0.26/0.35 1.00 1.50 0.040 0.015 - 12.0/14.0 - - -
X39Cr13 1.4031 0.36/0.42 1.00 1.00 0.040 0.015 - 12.5/14.5 - - -
X7CrNiAl17-7 1.4568 0.09 0.70 1.00 0.040 0.015 - 16.0/18.0 - 6.5/7.8 Al:0.70/1.50
X10CrNi18-8 1.4310 0.05/0.15 2.00 2.00 0.045 0.015 0.11 16.0/19.0 0.80 6.0/9.5 -
X5CrNi18-10 1.4301 0.07 1.00 2.00 0.045 0.015 0.11 17.5/19.5 - 8.0/10.5 -
X5CrNiMo17-12-2 1.4401 0.07 1.00 2.00 0.045 0.015 0.11 16.5/18.5 2.0/2.50 10.0/13.0 -
X11CrNiMnN19-8-6 1.4369 0.07/0.15 0.50/1.00 5.0/7.5 0.030 0.015 0.20/0.30 17.5/19.5 - 6.5/8.5 -
X12CrMnNiN17-7-5 1.4372 0.15 1.00 5.5/7.5 0.045 0.015 0.05/0.25 16.0/18.0 - 3.5/5.5 -

The specified tensile ranges and the 'available' tensile strength levels, by grade, are tabulated below.

Steel name Number +C700 +C850 +C1000 +C1150 +C1300 +C1500 +C1700 +C1900 Hardness
X6Cr17 1.4016 X X NA NA NA NA NA NA 200/300
X20Cr13 1.4021 X X NA NA NA NA NA NA -
X30Cr13 1.4028 X X NA NA NA NA NA NA -
X39Cr13 1.4031 X X NA NA NA NA NA NA -
X7CrNiAl17-7 1.4568 NA NA X X X X X NA -
X10CrNi18-8 1.4310 NA X X X X X X X 250/600
X5CrNi18-10 1.4301 X X X X X NA NA NA 220/450
X5CrNiMo17-12-2 1.4401 X X X X X NA NA NA 220/400
X11CrNiMnN19-8-6 1.4369 NA X X X X X NA NA 300/475
X12CrMnNiN17-7-5 1.4372 NA X X X X X NA NA 250/500

Available tensile strength levels in MPa (N/mm2) are:-

+C700 = 700/850: +C850 = 850/1000: +C1000 = 1000/1150: +C1150 = 1150/1300; +C1300 = 1300/1500: +C1500 = 1500/1700: +C1700 = 1700/1900: +C1900 = 1900/2200

NOTES
Martensitic grades 1.4021, 1.4028 and 1.4031 should also be available in the annealed condition.

Precipitation hardening grade 1.4568 should also be available in the solution annealed condition.

Total hardness Vickers ranges apply to ferritic and austenitic types only. Steels can be supplied to any HV aim value within the range.

The table below shows approximate equivalents of the TR designations in BS 5770

BS 5770 Designation Approximate Equivalent UTS Range (MPa) Nearest Equivalent Condition in EN 10151                                
TR 500 > 1550 +C1500
TR 380 > 1230 +C1300
TR 330 1050/1230 +C1000/+C1150
TR 280 910/1050 +C850/+C1000
TR 230 750/910 +C700/+C850

BSEN 10270-3 stainless steel wire for springs

BSEN 10270-3 was published in 2001 and replaced BS2056 (1991), which is now withdrawn. It contains only 3 grades, two austenitic and one precipitation hardening. (The grade compositions are also covered by BSEN 10088-3)

The BSEN 10270-3 has fewer grades than BS2056, which included the hardenable martensitic 420S45 and the highly alloyed austenitic 904S14 grades. There is also no austenitic with the enhanced nickel range of the 305S11 (11.0/13.0% Ni), which was for applications where low magnetic permeability in the cold drawn condition was required. BSEN 10270-3 grade 1.4310 is the alternative to BS2056 302S26 and 1.4401 the alternative to 316S33 and 316S42. Grade 1.4568 in BSEN 10270-3 is similar to the 301S81 of BS2056. These are NOT compositional equivalents. Annex B of BSEN 10270-3 shows a cross-reference table to former French, German and Swedish steel grades. The original standards should be consulted for grade comparisons.

BSEN 10270-3 grades and delivery conditions

The compositions of all the grades are shown below.
Values are maxima, unless there is a range stated.

Name Number C Si Mn P S Cr Mo Ni Others
X10CrNi18-8 1.4310 0.05/0.15 2.00 2.00 0.045 0.015 16.00/19.00 0.80 6.00/9.50 N:0.11
X5CrNiMo17-12-2 1.4401 0.07 1.00 2.00 0.045 0.015 16.50/18.50 2.00/2.50 10.00/13.00 N:0.11
X7CrNiAl17-7 1.4568 0.09 0.70 1.00 0.040 0.015 16.00/18.00 - 6.50/7.80 Al:0.70/1.50
 

The specified minimum tensile strength levels, by grade, in the drawn or heat treated (1.4568 only) conditions are tabulated below.

 
Steel number   1.4310   1.4310   1.4401   1.4568   1.4568
Nominal diameter   Drawn Normal   Drawn High   Drawn   Drawn   Heat Treated
Below 0.20   2200   2350   1725   1975   2275
0.20-0.30   2150   2300   1700   1950   2250
0.30-0.40   2100   2250   1675   1925   2225
0.40-0.50   2050   2200   1650   1900   2200
0.50-0.65   2000   2150   1625   1850   2150
0.65-0.80   1950   2100   1600   1825   2125
0.80-1.00   1900   2050   1575   1800   2100
1.00-1.25   1850   2000   1550   1750   2050
1.25-1.50   1800   1950   1500   1700   2000
1.50-1.75   1750   1900   1450   1650   1950
1.75-2.00   1700   1850   1400   1600   1900
2.00-2.50   1650   1750   1350   1550   1850
2.50-3.00   1600   1700   1300   1500   1800
3.00-3.50   1550   1650   1250   1450   1750
3.50-4.25   1500   1600   1225   1400   1700
4.25-5.00   1450   1550   1200   1350   1650
5.00-6.00   1400   1500   1150   1300   1550
6.00-7.00   1350   1450   1125   1250   1500
7.00-8.50   1300   1400   1075   1250   1500
8.50-10.0   1250   1350   1050   1250   1500

Note diameter ranges include the minimum figure, but exclude the maximum figure.

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