A532 Class I Type A may also be called Ni-Hard 1. Ni-Hard 1 is a wear-resistant material known for its combination of abrasion resistance and impact strength. Ni-Hard 1 has higher carbon content, higher hardness, and wear resistance, and is suitable for abrasive wear conditions with small impact loads.
A532 Class I Type A Chemical Requirements Weight %
| Class | Type | Designation | Carbon | Manganese | Silicon | Nickel | Chromium | Molybdenum | Copper | Phosphorus | Sulfur |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Ⅰ | A | Ni-Cr-Hc | 2.8-3.6 | 2.0 max | 0.8 max | 3.3-5.0 | 1.4-4.0 | 1.0 max | … | 0.3 max | 0.15 max |
The as-cast hardness of Ni-Hard 1 typically ranges from 500 BHN (Brinell hardness number) depending on the section thickness of the casting. This material is relatively low-cost, making it an attractive option for many applications.
Heat treatment of Ni-Hard 1 and Ni-Hard 2
Because of its high carbon content, only medium or low-temperature heat treatments are performed.
Two heat treatment processes for Ni-Hard 1, 2:
- 275℃, 12~24H, air cooling, the austenite is transformed into bainite, and the as-cast martensite is tempered, thereby improving the hardness and impact fatigue life.
- 450℃, 4H, air cooling or furnace cooling to room temperature; or cool to 275℃, then 275℃×(4~16)H, air cooling. This double heat treatment can reduce the carbon content in austenite. After subsequent heat treatment at 275°C, new bainite and martensite appear in the austenite phase transformation. Double heat treatment for higher impact fatigue life
However, over the past decade, many users have been transitioning from Ni-Hard 1 to ASTM A532 Class II and III materials. This is likely due to the improved properties and performance offered by these newer materials, which may better meet the specific requirements of certain applications.
It’s essential to consider the specific needs of your application, such as the level of wear and impact resistance required, as well as budget constraints, when selecting the most appropriate material.
