ASTM A436 Type 1 – Austenitic Gray Iron
on March 25, 2025
An Overview of ASTM A436 Type 1
ASTM A436 Type 1 austenitic gray iron can be a good material when resistance to heat, corrosion and wear is needed. It has low thermal expansion coefficients, non-magnetic properties and good toughness at low temperatures.
This material is characterized by uniformly distributed graphite flakes, some carbides, and sufficient alloy content to produce the austenitic structure. Alloying elements used in austenitic gray iron are chromium, nickel, copper, and sometimes molybdenum.
Note: Chromium can reduce growth in gray irons in environments >450C. Nickel improves scaling resistance, while also increasing toughness and strength at elevated temperatures.
Type 1 (and 1b) are exclusively designed for corrosion resistant applications.
Pro Tip: Type 2 is recommended for applications where copper contamination cannot be tolerated.
The characteristics of austenitic gray iron come from chemical control and heat treatment. The ASTM A436 specification provides chemical and mechanical requirements as below.
Chemical Requirements- ASTM A436 Type 1
| C | Mn | Si | Cr | Ni | Cu | S | |
|---|---|---|---|---|---|---|---|
| Min% | 0.5 | 1.00 | 1.5 | 13.5 | 5.50 | ||
| Max% | 3.00 | 1.5 | 2.80 | 2.5 | 17.5 | 7.50 | 0.12 |
Mechanical Requirements - ASTM A436 Type 1
| Minimum Tensile Strength ksi (MPa) | 25 (172) |
|---|---|
| Brinell Hardness | 131-183 |
Physical and Mechanical Properties
| Density lb/in3 (g/cm3) | 0.257(7.1) |
| Thermal Conductivity Btu/hr·ft·F (W/m·K) | 35 (60) |
| Specific Heat at 70F Btu/lb·F (J/kg·K) | 0.11(470) |
| Coefficient of Thermal Expansion Ɛ/F(Ɛ/C)X106 | 10-12 |
| Melting Temperature (F) | 2200 F |
| Compressive Strength ksi (MPa) | 29-58 (200-400) |
ASTM A436 Type 1 Austenitic Gray Iron Design Benefits
- Improved strength and toughness
- Enhanced wear resistance
- Corrosion resistance
- Improved heat resistance
- Increased durability
- Castability
Applications for ASTM A436 Type 1
There are several applications for austenitic gray iron, ASTM A436 Type 1:
- Chemical processing components
- Marine environments
- Engine components
- Gears
- Brakes
Reference: ASM Handbook Volume 1 and 1A
Read: For more information on gray iron, check out our gray iron webpage.
