304Cu is based on the familiar grade 304 with a significant addition of copper. This reduces the work hardening of the steel to allow operations such as cold heading, thread rolling and improved machining.
Approximate Composition – 18% Cr, 9%Ni, 3.5% Cu, 0.03% C(Exact composition ranges vary between EN and ASTM standards).
This grade combines the following characteristics:
- Good corrosion resistance similar to 304. Better than 304 in sulphuric acid due to copper addition
- Reduced work hardening allowing cold heading and thread rolling
- Resistance to becoming magnetic during cold working
- Easier machining than 304 due to lower work hardening. Approximately 25% improvement
304Cu is one of several grades that falls into the fastener grade A2. A2 is often thought of as equivalent to 304. However A2 has a maximum Cu of 4% which allows 304Cu to be included.
Applications which illustrate these features include:
Fasteners, intricate machined components, automotive industry, electronics, chemical processing, food and drink, double glazing pins, water meter disc spindles.