Q:
I work in the fusion technology field, specifically in a plasma physics laboratory. We are currently using a large number of A-286 screws. The screws have to withstand the high pre-loads required to insure the ultra high vacuum tightness of our facilities (generating stresses in the screws of up to 400 MPa or 58 ksi), from 20°C to 250°C (68°F to 482 °F). They have to be non-magnetic as well (relative magnetic permeability 400 MPa or 60 ksi, at temperatures up to 250°C or 482 °F, and relative magnetic permeability 1.01). The A286 screws are working well, but I’m looking for a lower cost alternative that can handle these conditions as we require thousands of screws.
I work in the fusion technology field, specifically in a plasma physics laboratory. We are currently using a large number of A-286 screws. The screws have to withstand the high pre-loads required to insure the ultra high vacuum tightness of our facilities (generating stresses in the screws of up to 400 MPa or 58 ksi), from 20°C to 250°C (68°F to 482 °F). They have to be non-magnetic as well (relative magnetic permeability 400 MPa or 60 ksi, at temperatures up to 250°C or 482 °F, and relative magnetic permeability 1.01). The A286 screws are working well, but I’m looking for a lower cost alternative that can handle these conditions as we require thousands of screws.
A:
For your application I would suggestion grade 5 Titanium screws. This grade of titanium is particularly strong with a high strength to weight ratio. Titanium screws offer slightly less tensile strength than A286 (148 ksi UTS vs 167 ksi UTS) but a higher yield strength of 137ksi vs 111ksi for A286. Titanium screws are also usable to able 500F. Titanium screws are also non-magnetic.