Designation System for Stainless Steel (ISO 3506 1979)

Composition Groups Austenitic Ferritic Martensitic
Identification of Steel Grades A1, A2, A4 F1 C1, C4 C3
Property Class 50 70 80 45 60 50 70 80
Soft Cold-Worked High-Strength Soft Cold-Worked Soft

Hardened

and

Tempered

Hardened

and

Tempered

Stainless Steel Properties

Extract from DIN 267 Part 11 – Chemical Composition of austenitic chromium-nickels steels in % by weight

Austenitic

Grade

 Material No. to AISI C Si Mn P S Cr Mo Ni
A1 303 0.12 1.0 2.0 0.20 0.15 to 0.35 17.0 to 19.0 0.6 8.0 to 10.0
A2 304 0.08 1.0 2.0 0.05 0.03 17.0 to 20.0 – 8.0 to 13.0
A4 316 0.08 1.0 2.0 0.05 0.03 16.0 to 18.5 2.0 to 3.0 10.0 to 14.4
  • Maximum values unless otherwise stated.
  • Types A2 and A4 may contain up to a maximum of 4% copper.
  • The selection of steel grades within a group is the prerogative of the manufacturer, unless the purchaser has specified particular steels to ISO or national standards.
  • Different grades of steel may be used as long as all physical and mechanical properties and the corresponding corrosion resistance of the finished product are achieved.  Only when all these conditions are fulfilled may finished articles be marked in accordance with DIN 267 Part 11.

Mechanical Properties-Austenitic Grades

Bolts, Screws and Studs

Grade

Property

Class

Tensile Strength Rm MPa

(N/mm2) minimum

Yield Stress Rp 0.2 Mpa

(N/mm2) minimum

 Elongation AL Minimum Diameter Range

A2

and

A4

 70 700 450 0.4d =<M20
80 800 600 0.3d =<M20

Comparison: US and ISO (DIN) Stainless Steels

Tensile Load

A2 and A4 as compared to 304 and 316 Percent difference from US – Stainless Steel
up to M20 44% higher
M22 and over 6% lower

Selection of Diameters - Tightening Torques, Loads

Guideline values for screws in steel groups A2-70 and A4-70 with standard metric threads to DIN 13

Diameter Load 1)Force at 0.2% yield point N Initial Stressing ForceN

Tightening Torque

Nm

 Force in service N
Axial Static Axial Dynamic Radial Static or Dynamic
M3 2250 1420 0.9 610 360 120
M4 3960 2490 2.2 1070 640 210
M5 6390 4030 4.3 1730 1040 350
M6 9040 5700 7.3 2440 1470 490
M8 16470 10380 17.7 4450 2670 890
M10 26100 16440 35.5 7050 4230 1410
M12 37930 23900 61.3 10240 6150 2050
M16 70650 44510 147.1 19080 11450 3820
M20 110250 69460 285.1 29770 17860 5950

1)The values correspond to 100% of the 0.2%

Notes on application:

  • When selecting the correct screw diameter it should be ensured that the total load on the screw does not exceed 90% of the standardized 0.2% yield stress.  Care should be taken to ensure correct initial tensioning, with a torque wrench wherever possible.

  • Experience has shown that a utilization of 70% of the total load is reasonable average for the initial stressing force to allow additional forces in service to be taken up.

**The table above is only intended as an aid for quick comparison**

Comparative International Stainless Steel Grades

British French German Italian Japanese Swedish USA
304S21 Z12CN17.08 1.4310 X12CrNi 17 07 SUS301 14 23 31 301
304S31 SUS302 14 23 32 302
304S15304S16 Z8CN18.09 1.4301 X5CrNi 18 10 SUS301 14 23 33 304
304S11 Z2CN18.10 1.4306 X2CrNi 18 11 SUS304L 14 23 52 304L
305S19 Z8CN18.12 X8CrNi 18 12 SUS305 305
309S24 Z15CN24.13 X16CrNi 23 14 SUS309 309
310S24 Z12CN25.20 1.4845 Z22CrNi 25 20 SUS310S 14 23 61 310
315S16 14 23 40
316S31316S33 Z6CND17.11 1.44011.4436 X8CrNiMo 17 13 SUS316 14 23 4314 23 47 316
316S11316S13 Z2CND17.12 1.44041.4435 X2CrNiMo 17 12 SUS316L 14 23 5314 23 48 316L
317S12 Z2CND19.15 1.4435 X2CrNiMo 18 16 SUS317L 14 23 67 317L
317S16 1.4436 SUS317 14 23 66 317
320S31320S33 Z8CND17.12 1.45711.4573 14 23 50
321S31 Z6CNT18.12 1.4541 X6CrNiTi 18 11 SUS321 14 23 37 321
347S31 Z6CNNb18.11 1.4558 X6CrNiNb 18 11X8CrNiNb 18 11 SUS347 14 23 38 347
403S17 Z6C13 1.4000 X6Cr13 SUS403 14 23 01 403
405S17 Z6CA13 1.4002 Z6CrA1 13 SUS405 405
409S19 1.4512 409
430S17 Z8C17 1.4016 X8Cr 17 SUS430 14 23 20 430
434S17 Z8CD17.01 1.4113 X8CrMo 17 SUS434 14 23 25 434
410S21 Z12C13 1.40061.4024 X12Cr 13 SUS410 13 23 02 410
410S45 Z30C13 X30Cr 13 SUS420JS 14 23 04 420

All information is strictly informative