201 Type 1 1 Ni-Resist Iron
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201 Type 1 1 Ni-Resist Iron
Overview
Dura-Bar Ni-Resist irons contain an austenitic matrix of approximately 10% alloy carbides. The austenitic structure is suitable for corrosive environments in sour well oils, salts, salt water acids and alkalies. The iron is relatively soft and chrome is added to produce carbides that help improve wear resistance. Ni-Resist is denser than gray or ductile irons and has a higher coefficient of thermal expansion. Dura-Bar Type 1 Ni-Resist is manufactured to produce a material conforming to ASTM A436. To learn more, download the Dura-Bar 201 Type 1 Ni-Resist Iron Product Brief.
Microstructure
The microstructure will consist of Type VII, A, size 4-6 graphite as defined in ASTM A247. The matrix will be austenite with 5-10% alloy carbide. The edge or rim will contain Type D graphite, size 6-8. Chill carbides are less than 5% in any field at 100x and will be well dispersed.
Center Area
100x, etched in 5% Nital
Edge Area
100x, etched in 5% Nital
Heat Treat Response
Austenitic alloys cannot be hardened by heat treatment. They may be softened and homogenized by heating to 1800-1900° F (980-1040° C) for three to five hours and air-cooling. This breaks down some of the carbides and most of those remaining will be spheroidized. Anneal softens the material without detrimental effect on the strength properties. Type 1 Ni-Resist should not be used in applications involving service above 1300° F (430° C).
Technical Specifications
Chemical Composition
Carbon and silicon targets are specified for each bar size in order to control the size and shape of the graphite flake. Titanium is added as an inoculant in order to produce the Type D graphite structure.
| Element | Percentage |
|---|---|
| Carbon | 3.00% Max |
| Silicon | 1.00 - 2.80% |
| Manganese | 0.50 - 1.50% |
| Nickel | 13.50 -17.50% Max |
| Copper | 5.50 - 7.50% |
| Chromium | 1.50 - 2.50% |
| Sulfur | 0.12% Max |
Mechanical Properties
Brinell hardness values for nominal as-cast diameters are shown in the table. Hardness properties listed are minimum, maximum across the bar. Hardness values for rectangles and squares are a function of the height and width ratios and will be supplied on request. BHN in the center of bars 1.750" and smaller may be lower than the values shown because of thermal center microshrinkage.
| Size Range | BHN | ||
|---|---|---|---|
| Inches | mm | Min | Max |
| 1.000 - 6.000 | 25 - 152 | 131 | 183 |
Tensile strength is determined from a separately cast, ASTM "B" test bar. Separately cast test bars will meet the minimum strength in pounds per square inch in the table below. Additionally, a test bar is removed from the continuous cast bar for reference, as tensile strength varies with section thickness and bar diameter.
| Mechanical Properties | |
|---|---|
| Tensile strength psi (min) | 40,000 |
| Yield strength psi (min) | n/a* |
| Elongation (min) | n/a* |