BS 970 (Part 1):1983 826M40: 826M40 is an alloy steel grade specified in BS 970 Part 1:1983 (Table 6, category 1). Section three of the standard advises that category 1 steels be used for new designs and established designs whenever possible.
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Mn
Cr
Mo
Ni
P
S
0.36-0.44
0.45-0.70
0.50-0.80
0.45-0.65
2.30-2.80
<=0.035
<=0.040
More data from BS 970 (Part 1):1983
From the standard
Other composition limits
Phosphorus and sulphur, Z condition
0.025 max each, unless otherwise agreed (note 20)
Phosphorus and sulphur
P 0.035 max, S 0.040 max, alloy steels (clause 1.7.2.1)
Source: BS 970 (Part 1):1983, Table 6
Heat treatment and maximum hardness (through hardening)
Hardening temperature
820-850 deg C
Quenching medium
Oil
Tempering temperature
660 deg C max
Hardenability test
No hardenability data specified
Maximum hardness HB, softened condition
255
Maximum hardness HB, temper softened condition
277
Heat treatment to be given to test bars and to material required in the finally heat treated condition. Note 24: O = oil, W = water. Where oil hardening is specified, either a well-agitated conventional oil or a proven synthetic quenchant may be used. Synthetic quenchants shall not be used for the heat treatment of test bars for material not supplied in the finally heat treated condition. Note 27: tempering between 280 deg C and 500 deg C should be avoided.
Source: BS 970 (Part 1):1983, Table 7
Mechanical properties by heat treatment condition
Condition
Limiting ruling section (mm)
Rm (N/mm2)
Re min (N/mm2)
A min (%)
Izod min (ft lbf)
KCV min (J)
Rp0.2 min (N/mm2), when specifically ordered
HB
U
250
925-1075
740
12
25
28
725
269-331
U
150
925-1075
755
12
35
42
740
269-331
V
250
1000-1150
835
12
25
28
820
293-352
V
150
1000-1150
850
12
35
42
835
293-352
W (note 11)
250
1075-1225
925
11
20
22
910
311-375
W (note 11)
150
1075-1225
940
11
30
35
925
311-375
X (note 11)
150
1150-1300
1020
10
25
28
1005
341-401
Y (note 11)
150
1225-1375
1095
10
25
28
1080
363-429
Z (note 11)
100
1550 min
1235
7
10
11
1125
444 min
Values as printed in Table 6 for the limiting ruling section shown. Rp0.2 applies when specifically ordered (note 10). 1 N/mm2 = 1 MPa. Note 11: often ordered in the softened condition for machining and subsequent heat treatment to achieve these specified mechanical properties.
Source: BS 970 (Part 1):1983, Table 6
Mechanical properties, bright bar
Condition
Heat treatment condition
Size, diameter or across flats (mm)
Rm (N/mm2)
Re min (N/mm2)
A min (%)
Izod min (ft lbf)
KCV min (J)
Rp0.2 min (N/mm2), when specifically ordered
HB
Hardened and tempered + turned or ground
U
over 150 to 250
925-1075
740
12
25
28
725
269-331
Hardened and tempered + turned or ground
U
over 100 to 150
925-1075
755
12
35
42
740
269-331
Hardened and tempered + turned or ground
V
over 63 to 250
1000-1150
835
12
25
28
820
293-352
Hardened and tempered + turned or ground
V
over 63 to 150
1000-1150
850
12
35
42
835
293-352
Hardened and tempered + turned or ground
W (note 11)
over 29 to 250
1075-1225
925
11
20
22
910
311-375
Hardened and tempered + turned or ground
W (note 11)
over 29 to 150
1075-1225
940
11
30
35
925
311-375
Hardened and tempered + turned or ground
X (note 11)
over 29 to 150
1150-1300
1020
10
25
28
1005
341-401
Hardened and tempered + turned or ground
Y (note 11)
over 29 to 150
1225-1375
1095
10
25
28
1080
363-429
Hardened and tempered + turned or ground
Z (note 11)
over 29 to 100
1550 min
1235
7
10
11
1125
444 min
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
U
over 100 to 150
925-1075
770
9
35
-
755
269-331 (note 4)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
V
over 63 to 150
1000-1150
865
9
35
-
850
293-352 (note 4)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
W (note 11)
over 29 to 150
1075-1225 (note 12)
955
8
30
-
940
311-375 (note 4)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
X (note 11)
over 29 to 150
1150-1300 (note 12)
1035
7
25
-
1020
341-401 (note 4)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
Y (note 11)
over 29 to 150
1225-1375 (note 12)
1010
7
25
-
1095
363-429 (note 4)
Hardened and tempered + cold drawn or hardened and tempered + cold drawn + ground
Z (note 11)
over 29 to 100
1550 min (note 12)
1250
5
10
-
1235
444 min (note 4)
Turned, ground or cold drawn and finally softened
-
-
-
-
-
-
-
-
277 max
Size is the diameter or across flats. For cold drawn bar of 6 mm or less, all mechanical properties are subject to agreement between purchaser and supplier at the time of enquiry and order (note 8). For normalizing and hardening and tempering treatments see Tables 3 and 7 (note 9). Rp0.2 applies when specifically ordered (note 10). 1 N/mm2 = 1 MPa. Hardness values marked note 4 are for guidance only. Note 11: often ordered in the softened condition for machining and subsequent heat treatment to achieve these specified mechanical properties. Note 12: cold drawn bars are not normally available in this tensile strength range.
Appendix D note 47: where a comparison is made the steels are not necessarily equivalent. 'Not listed' means the earlier edition has no entry under this designation.
Source: BS 970 (Part 1):1983, Appendix D
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