Steel 18KHGT
Description
Steel 18KHGT
Steel 18KhGT: a brand of steels and alloys. Below is the systematized information on the purpose, chemical composition, types of supplies, substitutes, temperature of critical points, physical, mechanical, technological and casting properties for the grade — Steel 18HGT.
General information about steel 18HGT
Substitute brand |
Steel: 30KHGT, 25KHGT, 12KHN3A, 12KHN2N4A, 20KHN2N, 14KHGSN2MA, 20KHGR. |
Delivery type |
Sheet 18khgt, circle 18khgt, long products, including shaped: GOST 4543−71, GOST 259071, GOST 2591−71, GOST 2879−69. Calibrated bar GOST 7417−75, GOST 8559−75, GOST 8560−78, GOST 1051−73. Polished bar and silver bar GOST 4543−71, GOST 14955−77. Strip GOST 103−76. Forgings and forged billets GOST 1133−71. |
Application |
Critical refining or case-hardening parts that require increased core strength and toughness and high surface hardness when exposed to impact loads. |
Chemical composition of steel 18HGT
Chemical element |
% |
Silicon (Si) |
0.17−0.37 |
Manganese (Mn) |
0.80−1.10 |
Copper (Cu), no more |
0.30 |
Nickel (Ni), no more |
0.30 |
Sulfur (S), no more |
0.035 |
Titanium (Ti) |
0.03−0.09 |
Carbon (C) |
0.17−0.23 |
Phosphorus (P), no more |
0.035 |
Chromium (Cr) |
1.00−1.30 |
Mechanical properties of steel 18HGT
Section, mm |
σ 0.2, MPa |
σ B, MPa |
δ 5 ,% |
ψ,% |
KCU, J / m 2 |
HB |
HRC e |
Normalization 880−950 ° C. Hardening 870 ° С, oil. Vacation 200 ° C, air or water. |
Samples |
880 |
980 |
nine |
50 |
78 |
|
|
Normalization 930−960 ° C. Cementation 930−950 ° C. Hardening 825−840 ° С, oil. Vacation 180−200 ° C. |
|
360 |
640 |
|
|
|
157−207 |
|
50 |
800 |
1000 |
nine |
|
|
285 |
57−63 |
Cementation 920−950 ° С, air. Hardening 820−860 ° С, oil. Vacation 180−200 ° C, air. |
20 |
930 |
1180 |
ten |
50 |
78 |
341 |
53−63 |
60 |
780 |
980 |
nine |
50 |
78 |
240−300 |
57−63 |
Mechanical properties at elevated temperatures
test t, ° C |
σ 0.2, MPa |
σ B, MPa |
δ 5 ,% |
δ 4 ,% |
ψ,% |
HB |
Normalization |
20 |
420 |
520 |
|
26 |
77 |
156 |
200 |
360 |
460 |
|
24 |
78 |
|
300 |
310 |
465 |
|
24 |
68 |
|
400 |
300 |
470 |
|
29 |
75 |
|
500 |
300 |
410 |
|
27 |
76 |
|
600 |
240 |
325 |
|
45 |
86 |
|
Sample 6 mm in diameter, 30 mm long, forged and normalized. Deformation rate 50 mm / min. Strain rate 0.03 1 / s |
700 |
205 |
235 |
46 |
|
88 |
|
800 |
76 |
135 |
51 |
|
94 |
|
900 |
54 |
95 |
55 |
|
96 |
|
1000 |
50 |
78 |
58 |
|
100 |
|
1100 |
25 |
43 |
61 |
|
100 |
|
1200 |
thirteen |
25 |
56 |
|
100 |
|
Mechanical properties depending on the tempering temperature
vacation t, ° С |
σ 0.2, MPa |
σ B, MPa |
δ 5 ,% |
ψ,% |
KCU, J / m 2 |
HRC e |
Hardening 880 ° С, oil. |
200 |
1150 |
1370 |
eleven |
57 |
98 |
41 |
300 |
1150 |
1330 |
ten |
57 |
78 |
41 |
400 |
1150 |
1210 |
nine |
57 |
78 |
40 |
500 |
950 |
940 |
fifteen |
66 |
144 |
32 |
600 |
720 |
780 |
20 |
73 |
216 |
22 |
Mechanical properties depending on the section
Section, mm |
σ 0.2, MPa |
σ B, MPa |
δ 5 ,% |
ψ,% |
KCU, J / m 2 |
HRC e |
Hardening 850 ° С, oil. Vacation 200 ° C, air. |
five |
1320 |
1520 |
12 |
50 |
72 |
|
fifteen |
930 |
1180 |
thirteen |
50 |
78 |
38 |
20 |
730 |
980 |
fifteen |
55 |
113 |
thirty |
25 |
690 |
980 |
19 |
50 |
93 |
28 |
Technological properties of steel 18HGT
Forging temperature |
Beginning 1200, end 800. Sections up to 250 mm are cooled in air, 251−350 mm — in a pit. |
Weldability |
welded without restrictions (except for chemically-thermally treated parts). Welding methods: RDS, KTS. |
Machinability by cutting |
After normalization at HB 156−159 σ B = 530 MPa K υ tv.spl. = 1.1, K υ b.st. = 1.0. |
Tendency to release ability |
not inclined |
Flock sensitivity |
not sensitive |
Temperature of critical points of steel 18HGT
Critical point |
° C |
Ac1 |
740 |
Ac3 |
825 |
Ar3 |
730 |
Ar1 |
650 |
Mn |
360 |
Impact strength of steel 18HGT
Impact strength, KCU, J / cm 2
Delivery status, heat treatment |
+20 |
-20 |
-40 |
-60 |
|
114 |
101 |
93 |
85 |
Endurance limit of steel 18HGT
σ -1, MPa |
τ -1, MPa |
n |
σ B, MPa |
σ 0.2, MPa |
Heat treatment, steel condition |
490 |
294 |
|
980 |
780 |
Sample with a cross section of 50 mm, HB 240−300 |
637 |
|
1E + 6 |
|
|
Cementation 960 C, hardening 840 C, oil, tempering 180−200 C, HB 240−300. |
|
480 |
5E + 6 |
|
|
Normalization 1100 C, cooling up to 870 C, quenching in oil, tempering 200 C, HB 415. |
Hardenability of steel 18HGT
Hardening 900 C. Hardness for strips of hardenability HRCe.
Distance from the end, mm / HRC e |
1.5 |
3 |
4.5 |
6 |
7.5 |
nine |
12 |
fifteen |
eighteen |
21 |
41.5−50.5 |
39.5−49.5 |
36.5−47.5 |
33−46 |
30−44.5 |
27.5−42.5 |
24.5−42.5 |
23−37.5 |
35.5 |
34 |
Amount of martensite,% |
Crit. Diam. in water, mm |
Crit. Diam. in oil, mm |
Crete. hardness, HRCэ |
50 |
33−82 |
12−52 |
32−36 |
90 |
23−48 |
6−24 |
38−43 |
Physical properties of steel 18HGT
Test temperature, ° С |
20 |
100 |
200 |
300 |
400 |
500 |
600 |
700 |
800 |
900 |
Normal elastic modulus, E, GPa |
211 |
205 |
197 |
191 |
176 |
168 |
155 |
136 |
129 |
|
Torsional shear elastic modulus G, GPa |
84 |
80 |
77 |
75 |
68 |
66 |
59 |
52 |
49 |
|
Density of steel, pn, kg / m 3 |
7800 |
|
|
|
|
|
|
|
|
|
Thermal conductivity coefficient W / (m ° С) |
37 |
38 |
38 |
37 |
35 |
34 |
31 |
thirty |
29 |
|
Test temperature, ° С |
20−100 |
20−200 |
20−300 |
20−400 |
20−500 |
20−600 |
20−700 |
20−800 |
20−900 |
20−1000 |
Linear expansion coefficient (a, 10−6 1 / ° С) |
10.0 |
11.5 |
12.3 |
12.8 |
13.3 |
13.6 |
|
|
|
|
Specific heat (C, J / (kg ° C)) |
495 |
508 |
525 |
537 |
567 |
588 |
626 |
705 |
|
|