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ISO 898 PART 1 – 2013 (EXTRACT)

  • Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws and studs with specified property classes — Coarse thread and fine pitch thread

ISO 898-1:2013 specifies mechanical and physical properties of bolts, screws and studs made of carbon steel and alloy steel when tested at an ambient temperature range of 10°C to 35°C. Fasteners (the term used when bolts, screws and studs are considered all together) that conform to the requirements of ISO 898-1:2013 are evaluated at that ambient temperature range. They might not retain the specified mechanical and physical properties at elevated temperatures (see Annex B) and/or lower temperatures. Certain bolts and screws might not fulfil the tensile or torsional requirements of ISO 898-1:2013 because the geometry of their heads reduces the shear area in the head compared to the stress area in the thread. These include bolts and screws having a low or countersunk head.
ISO 898-1:2013 is applicable to bolts, screws and studs


  • made of carbon steel or alloy steel,
  • having triangular ISO metric screw thread in accordance with ISO 68-1,
  • with coarse pitch thread M1,6 to M39, and fine pitch thread M8x1 to M39x3,
  • with diameter/pitch combinations in accordance with ISO 261 and ISO 262, and
  • having thread tolerances in accordance with ISO 965-1, ISO 965-2 and ISO 965-4.

It is not applicable to set screws and similar threaded fasteners not under tensile stress (see ISO 898-5).

It does not specify requirements for such properties as weldability, corrosion resistance resistance to shear stress, torque/clamp force performance (for test method, see ISO 16047), or fatigue resistance.


Chemical composition as per ISO 898-1 for typical grades

CLASS MATERIAL AND TREATMENT C C P S B TEMPERING TEMP. [C]
MIN MAX MAX MAX MAX
8.8 CARBON STEEL WITH ADDITIVES (E.G. B, MN OR CR) QUENCHED AND TEMPERED 0.15 (D) 0.4 0.025 0.025 0.003 425
CARBON STEEL QUENCHED AND TEMPERED 0.25 0.55 0.035 0.025
10.9 CARBON STEEL WITH ADDITIVES (E.G. B, MN OR CR) QUENCHED AND TEMPERED 0.15 (D) 0.35 0.025 0.025 0.003 340
CARBON STEEL QUENCHED AND TEMPERED 0.25 0.55 0.025 0.025 0.003 425
CARBON STEEL WITH ADDITIVES (E.G. B, MN OR CR) QUENCHED AND TEMPERED 0.20 (D) 0.55 0.025 0.025
ALLOY STEEL QUENCHED AND TEMPERED (G) 0.2 0.55 0.025 0.025
12.9 ALLOY STEEL QUENCHED AND TEMPERED (G) 0.28 0.5 0.025 0.025 0.003 380

(D) IN CASE OF PLAIN CARBON BORON STEEL WITH A CARBON CONTENT BELOW 0.25% (LADLE ANALYSIS), MIN MANGANESE 0.6% FOR 8.8 AND 0.7% FOR 10.9

(G) ALLOY STEEL SHALL CONTAIN ONE OF THE FOLLOWING ELEMENTS: CHROMIUM 0.30%, NICKEL 0.30%, MOLYBDENUM 0.20%, VANADIUM 0.10%


Mechanical properties of screws and studs according to EN ISO 898-1:2013 Property class 4.6 to 12.9.


No. Mechanical properties property classes
4,6 4,8 5,6 5,8 6,8 8.8 8,8 9,8 10,9 12,9
d<16 mmᵃ d>16 mmᵇ d<16 mm
1 Tensile strength, Rm, MPa nom. ° 400 500 600 800 900 1000 1200
min. 400 420 500 520 600 800 830 900 1040 1220
2 Lower proof stress ReL ᵈ, MPa nom. ᶜ 240 – 300 – – – – – – –
min. 240 – 300 – – – – – – –
3 Yield strength, Rp0.2, MPa nom. ᶜ – – – – – 640 640 720 900 1080
min. – – – – – 640 660 720 940 1100
4 Yield strength at 0.0048 d for whole screw, Rpf, MPa nom. ᶜ – 320 – 400 480 – – – – –
min. – 340ᵉ – 420ᵉ 480ᵉ – – – – –
5 Proof stress, Spᶠ, MPa nom. 225 310 280 380 440 580 600 650 830 970
Stress during proofing load testing ᴼ 0,94 0,91 0,93 0,90 0,92 0,91 0,91 0,90 0,88 0,88
6 Elongation after fracture (test specimen), A, % min. 22 – 20 – – 12 12 10 9 8
7 Contraction after fracture (test specimen), Z, % min. – 52 48 48 44
8 Elongation after fracture, Af (whole screw) min. – 0,24 – 0,22 0,20 – – – – –
9 Ductility in event of head soundness test Inget brott
10 Vickers hardness, HV min. 120 130 155 160 190 250 255 290 320 385
F ≥ 98 N max. 220ᵍ 250 320 335 360 380 435
11 Brinell hardness, HBW min. 114 124 147 152 181 238 242 276 304 366
F = 30 D² max. 209ᵍ 238 304 318 342 361 414
12 Rockwell hardness, HRB min. 67 71 79 82 89 –
max. 95,0ᵍ 99,5 –
Rockwell hardness, HRC min. – 22 23 28 32 39
max. – 32 34 37 39 44
13 Surface hardness, HV 0.3 max. – h h, i h, j
14 Min. height of non-decarburised zone, min. – ½ H1 ⅔ H1 ¾ H1
E, mm
Max. depth of complete decarburisation, max. – 0,015
G, mm
15 Reduction in hardness after re-annealing, HV max. – 20
16 Fracture torque, MB,Nm min. – regarding to ISO 898-7
17 Impact strength, Kᵥᵏ˴ˡ, J min. – 27 – 27 27 27 27 m
18 Surface defects ISO 6157-1ⁿ ISO
6157-3

a) The values do not apply to structural bolts.

b) For structural bolts ≥ M12.

c) Nominal values are only specified in order to indicate property class in the designation system.

d) If the lower proof stress ReL cannot be determined, it is permitted to measure the yield strength Rp0.2.

e) For property classes 4.8, 5.8 and 6.8, the values for Rpf min are under investigation.

f) Proof loads are specified in SS-EN ISO 898-1:2013.

g) Hardness determined at the end of the screw must be max. 250 HV, 238 HB or 99.5 HRB.

h) The surface hardness may not be more than 30 Vickers units higher than the measured core hardness determined with HV 0.3.

i) No surface hardness exceeding 390 HV is permitted.

j) No surface hardness exceeding 435 HV is permitted.

Hardness requirement as per ISO 898-1 for typical grades


HARDNESS SCALE CLASS 8.8 CLASS 8.8 CLASS 10.9 CLASS 12.9
M16 AND BELOW ABOVE M16
VICKERS, HV MIN. 250 255 320 385
MAX. 320 335 380 435
BRINELL, HB MIN. 238 242 304 366
MAX. 304 318 361 414
ROCKWELL, HRC MIN. 22 23 32 39
MAX. 32 34 39 44

All data for information purpose only. For more details on product standards or dimensions, please feel free to contact us at sales@nexoworld.in

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