Chemical Composition

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Chemical composition (%) (EN ISO 898-1:2013)

4.6Carbon steel -0.550.0500.060
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Strength class Material and heat treatment Chemical composition (analysis on the product) % Minimum hardening temperature °C
C
min		 C
max		 P
max		 S
max		 B
max		  
4.8 0.13 0.55 0.050 0.060    
5.6 - 0.55 0.050 0.060 Not specified -
5.8 0.15 0.55 0.050 0.060    
6.8            
8.8 Carbon or alloy steel (B, Mn, Cr), quenched and tempered 0,15 0,40 0,025 0,025 0,003 425
Quenched and tempered carbon steel 0,25 0,50 0,025 0,025
Quenched and tempered alloy steel 0,20 0,55 0,025 0,025
9.8 Carbon or alloy steel (B, Mn, Cr), quenched and tempered 0,15 0,40 0,025 0,025 0,003 425
Quenched and tempered carbon steel 0,25 0,50 0,025 0,025
Quenched and tempered alloy steel 0,20 0,55 0,025 0,025
10.9 Carbon or alloy steel (B, Mn, Cr), quenched and tempered 0,20(2) 0,55 0,025 0,025 0,003 425
Quenched and tempered carbon steel 0,25 0,55 0,025 0,025
Quenched and tempered alloy steel 0,20 0,55 0,025 0,025
12.9 Quenched and tempered alloy steel 0,30 0,50 0,025 0,025 0,003 425
12.9 Quenched and tempered carbon steel with the addition of Cr, B, Mn, Mo 0,28 0,50 0,025 0,025 0,003 380

For these classes it is possible to use free-cutting steel with maximum values of S=0.34%, P=0.11%, Pb=0.35% In order to obtain sufficient temperability with the nominal diameters >20 mm, it may be necessary to use steels of the 10.9 class In the case of carbon steels alloyed with boron with C

< 0.25, the manganese must be ≥ 0.6% for the strength class 8.8 and ≥ 0.7% for the strength classes 9.8 and 10.9 The class 12.9 differs from 10.9 for the different minimum hardening temperature

Mechanical characteristics (EN ISO 898-1:2013)

Characteristics Strength class
4.6 4.8 5.6 5.8 6.8 8.8 d≤16mm 8.8 d>16mm 9.8 10.9 12.9
Tensile strength Rm (MPa) nom 400 400 500 500 600 800 800 900 1000 1200
min 400 420 500 520 600 800 830 900 1040 1220
Yield strength Rm (MPa)
Rel up to 6.8 - Rp0,2 from 8.8		 nom 240 - 300 - - 640 640 720 900 1080
min 240 - 300 - - 640 660 720 940 1100
Elongation after fracture, a% min 22 - 20 - - 12 12 10 9 8
Necking Z%             52 52 48 48 44
Vickers hardness (HV)
F ≥ 98 N		 min 120 130 155 160 190 250 255 290 320 385
max 220 220 220 250 320 335 360 380 435  
Brinell hardness (HB)
F = 30D2		 min 114 124 147 152 181 238 242 276 304 314
max 209 209 209 238 304 318 342 361 414  
Rockwell hardness
HRB up to 6.8 - HRC from 8.8		 min 67 71 79 82 89 22 23 28 32 39
max 95 95 95 95 99,5 32 34 37 39 44
Resilience KV (J) – 20°C(1) min - - 27 - - 27 27 27 27 27