The primary difference between ASTM A216 WCC and ASTM A216 LCC casting grades lies in their suitability for low-temperature service, specifically determined by impact testing.
Understanding WCC and LCC Cast Steels
Both WCC and LCC are grades of cast carbon steel specified under the ASTM A216 standard, which covers steel castings intended for fusion welding for high-temperature service. While they are largely similar in composition and standard properties, LCC is specifically tested and certified for use in low-temperature environments where impact resistance is critical.
Key Distinction: Low-Temperature Service and Impact Testing
Based on the provided reference, the fundamental difference is:
- A216 LCC is essentially the same material as A216 WCC, but it undergoes Charpy impact testing at a temperature of -46ºC. This testing confirms its suitability and toughness for low-temperature service applications.
This means that while WCC is commonly used for high-temperature applications, LCC is specifically qualified to handle cold conditions without becoming brittle and susceptible to fracture under impact.
Comparing WCC and LCC Properties
The reference highlights some aspects of WCC in comparison to other grades (WCB and LCB), but the core comparison between WCC and LCC is focused on the low-temperature testing.
Let's break it down:
- A216 WCC:
- Suitable for high-temperature service.
- Has a slightly higher pressure/temperature rating compared to A216 WCB and A216 LCB.
- This higher rating is attributed to higher yield strength and slightly higher manganese content than WCB/LCB. (Note: The reference compares WCC to WCB/LCB here, not directly stating WCC itself requires impact testing at -46ºC).
- A216 LCC:
- Fundamentally the same material as A216 WCC in terms of basic composition and properties.
- Specifically charpy impact tested at -46ºC (-50ºF).
- Certified for low-temperature service.
Why is this distinction important?
Materials can lose toughness and become brittle at low temperatures. For applications like pipelines, valves, and fittings in cold climates or cryogenic processes, using a material certified for low temperatures (like LCC) is crucial for safety and reliability. The Charpy impact test is a standard method to assess a material's resistance to fracture under impact at specific temperatures.
Summary Table
| Feature | ASTM A216 WCC | ASTM A216 LCC |
|---|---|---|
| Base Material | Cast Carbon Steel | Cast Carbon Steel |
| Primary Use | High-Temperature Service | Low-Temperature Service |
| Relationship | Standard grade | Essentially WCC specially tested |
| Key Requirement | Meets standard properties | Meets standard properties AND must pass Charpy impact test at -46ºC |
| Impact Testing | Not specifically required at -46ºC for low-temp service | Required at -46ºC (-50ºF) |
In essence, if your application involves temperatures dropping to -46ºC or below where impact might occur, you require the LCC grade. If it's primarily a high-temperature application and low-temperature toughness isn't a specific requirement below standard ambient conditions, WCC may be sufficient.
