Countersunk Tek Screws or self drilling screws for fixing wood to steel.
For steel above 5mm thick use fine thread self drilling screws with a long drill point.
For steel up to 5mm use coarse thread with a short drill point.
Countersunk wingtek screws are available in steel or stainless steel. The steel version comes in zinc plated or an external coated type ie Ruspert, Ferrotek or Evoshield depending on the brand.
The external coated version has a 1000 hr salt spray tested coating which is suitable for external work. The zinc plated type has a lower level of protection but the cost is significantly lower.
The wood to steel self drilling screws are also available in stainless steel for additional corrosion protection. Various grades of stainless including A4, A2 and hardened stainless steel are available.
For a look at what other self drilling screws we offer please follow the link.