EN 10084:2008 20NiCrMoS6-4 Steel: Specifications & Listings
EN 10084:2008 20NiCrMoS6-4: A nickel chromium molybdenum alloy special steel for case hardening to EN 10084:2008 (steel number 1.6571), with controlled sulphur of 0.020 to 0.040% for better machinability. Supplied as semi-finished products, bars, rod, flat products and forgings (Table 1); intended for carburizing or carbonitriding and subsequent hardening, giving a hard surface layer and a tough core (clause 3.1).
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Cr
Mn
Mo
Ni
P
S
Si
0.16-0.23
0.60-0.90
0.50-0.90
0.25-0.35
1.40-1.70
<=0.025
0.020-0.040
<=0.40
Mechanical Properties
Condition
Soft annealed
Hardenability
+H band at 1.5 mm from the quenched end: 41 to 49 HRC
Hardness
Soft annealed: 229 HB max
More data from EN 10084:2008
From the standard
Other composition limitsTable 3 and its notes
Designation as printed
20NiCrMoS6-4
Steel number
1.6571
Classification
Alloy special steel (clause 4.1)
Improved machinability
Steels with sulphur up to about 0.10% or lead may be supplied on request; the upper manganese limit may then be 0.15 higher (Table 3, note c)
Elements not quoted in Table 3 are not intentionally added without the purchaser's agreement, other than for finishing the heat. With hardenability requirements, slight deviations from the cast analysis limits are permitted except for phosphorus and sulphur: carbon within 0.01%, other elements within Table 4.
Source: EN 10084:2008 (DIN EN 10084:2008-06), Table 3 and its notes
Hardness by delivery conditionTable 7
Treated to improve shearability (+S), max
255 HB
Soft annealed (+A), max
229 HB
Treated to hardness range (+TH)
179 to 229 HB
Treated to ferrite-pearlite structure and hardness range (+FP)
154 to 207 HB
Brinell hardness (HBW) for the conditions given in the standard; the values also apply to the grades with hardenability requirements (+H, +HH, +HL).
Source: EN 10084:2008 (DIN EN 10084:2008-06), Table 7
Hardenability, end quench test (+H)Hardness band
Hardness band (HRC, minimum to maximum) by distance from the quenched end (mm)
1.5
3
5
7
9
11
13
15
20
25
30
35
40
Distance from quenched end (mm)
1.5
3
5
7
9
11
13
15
20
25
30
35
40
Maximum, HRC
49
49
48
48
47
47
46
44
41
39
38
37
36
Minimum, HRC
41
40
39
36
33
30
28
26
23
21
Applies when ordered with the symbol +H; the hardenability requirements of Table 5 apply to alloy steels unless otherwise agreed (clause 7.1.2). End quench test at 880 deg C (Table 8).
Source: EN 10084:2008 (DIN EN 10084:2008-06), Table 5
Restricted hardenability (+HH, +HL), HRCTable 6
Limit
1.5 mm
3 mm
5 mm
7 mm
9 mm
11 mm
13 mm
15 mm
20 mm
25 mm
30 mm
35 mm
40 mm
HH max.
49
49
48
48
47
47
46
44
41
39
38
37
36
HH min.
44
43
42
40
38
36
34
32
29
27
26
25
24
HL max.
46
46
45
44
42
41
40
38
35
33
32
31
30
HL min.
41
40
39
36
33
30
28
26
23
21
-
-
-
Restricted scatter bands by distance from the quenched end; supplied if agreed at enquiry and order (clause 7.1.2).
Source: EN 10084:2008 (DIN EN 10084:2008-06), Table 6
Heat treatmentTable 8
End quench test, austenitizing
880 deg C
Carburizing
880 to 980 deg C
Core hardening
830 to 870 deg C
Case hardening
780 to 820 deg C
Tempering
150 to 200 deg C
Temperatures for carburizing, core hardening, case hardening and tempering are for guidance; the temperatures chosen should give the properties required. Austenitizing time for the end quench test as a guide 30 to 35 minutes, tempering at least 1 hour.
Source: EN 10084:2008 (DIN EN 10084:2008-06), Table 8
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