General Characteristics
AISI/SAE 4130 is a water-hardening alloy steel of low-to-intermediate hardenability. It retains good tensile, fatigue, and impact properties up to about 370 °C (700 °F); however, it has poor impact properties at cryogenic temperatures. This steel is not subject to temper embrittlement and can be nitrided. It usually is forged at 1100 to 1200 °C (2000 to 2200 °F); finishing temperature should never fall below 980 °C (1800 °F).
Available as billet, bar, rod, forgings, sheet, plate, tubing, and castings, 4130 steel is used to make automotive connecting rods, engine mounting lugs, shafts, fittings, bushings, gears, bolts, axles, gas cylinders, airframe components, hydraulic lines, and nitrided machinery parts.
Typical chemical composition
|
Weight %
|
C
|
Mn
|
Si
|
Cr
|
Ni
|
Mo
|
P
|
S
|
Fe
|
minimum
|
0.28
|
0.40
|
0.20
|
0.80
|
--
|
0.15
|
--
|
--
|
97.03-98.22
|
maximum
|
0.33
|
0.60
|
0.35
|
1.10
|
--
|
0.25
|
0.035
|
0.040 |
Physical properties (annealed condition)
|
Characteristics
|
|
English
|
Metric
|
Nominal density
(68°F/20°C)
|
|
0.284 lbs/in3
|
7.85 g/cm3
|
Specific heat
(212 °F/100°C)
|
|
0.114 BTU/lb - °F
|
477 J/KG- °K
|
Coefficient of thermal expansion
|
68°F – 212°F
20°C – 100°C
|
6.78 micro in/in- °F
|
12.2 micro m/m- °K
|
68°F – 752°F
20°C – 400°C
|
7.61 micro in/in- °F
|
13.7 micro m/m- °K
|
68°F – 1100°F
20°C – 600°C
|
8.11 micro in/in- °F
|
14.6 micro m/m- °K
|
Thermal conductivity
|
100°C
|
24.7 BTU/ft- hr - °F
|
42.7 W/m - °K
|
300°C
|
23.5 BTU/ft- hr - °F
|
40.6 W/m - °K
|
1200°C
|
17.4 BTU/ft- hr - °F
|
30.1 W/m - °K
|
Electrical properties
|
Electrical resistivity
|
20°C (68°F)
|
223 nΩ ∙ m
|
100°C (212°F)
|
271 nΩ ∙ m
|
400°C (752°F)
|
529 nΩ ∙ m
|
1200°C (2190°F)
|
1222 nΩ ∙ m |