The Addition of Copper to Stainless Steel

In the vast majority of stainless steel grades, copper appears only as a residual element but it can be added to the alloying mix to provide a range of advantages for certain applications.

The addition of copper to stainless steel helps to increase the ductility of the allot while decreasing its work-hardening rate. Improving ductility enables machining forces to be reduced, which permits increased machining speeds while minimising wear and tear on tools. In addition, the higher level of ductility reduces the potential for cracking during operations such as cold-forming, swaging and staking. 

Another quality of stainless steel that can be affected by the addition of copper to the alloying mix is a reduction in magnetic permeability. When 304 and 303 grades are subject to cold reduction, this increases magnetism slightly due to the material changing from austenitic to martensitic. It has been shown that the addition of copper can reduce the magnetic permeability of these stainless steel alloys by as much as 30%.

One of the most prized qualities of stainless steel is its resistance to corrosion and the addition of copper can further enhance this crucial property, especially when the stainless steel will be subject to oxidising acidic media. Such media cause a chemical reduction of the copper, which in turn causes a metallic film to form on the surface of the stainless steel. The film provides strong protection to the stainless steel and slows any growth of crevices and pits. 

Working within the demanding scope of our ISO 9001:2015 management system, BS Stainless is able to supply a variety of components made using stainless steel with added copper. One of the most versatile and widely-used of these components is cold heading wire, which offers a winning combination of strength and formability.

Cold heading wire of the specialised 302HQ grade contains 3% copper. The material is the standard for manuafcturing light machine screws and self-tapping screws, along with a wide variety of other stainless steel fixings and fasteners such as tie rods, studs, pins, rivets and bolts.

Further processing options are available, such as the addition of various coatings to improve the efficiency and performance of machining. Available coatings include metallic, copper and soap. 

For more information about cold heading wire, along with our comprehensive collection of other stainless steel wires and grades, please browse the BS Stainless website. Do not hesitate to get in touch with our technical team if you require expert advice.