High Performance Alloys for Critical Applications
15 September 2020
When an application calls for fasteners that can withstand atmospheric or chemical corrosion, elevated temperatures or a combination of both, fastener makers find themselves dealing with specifications and availability issues that aren’t a factor with the more common carbon steels.
Bolts, nuts, washers, rivets and other fasteners for jet engines, gas turbines, superchargers, afterburners, petrochemical processing parts and other critical aerospace equipment are made from special alloys that can withstand demanding conditions of heat, stress and corrosive environments. Applications like these are becoming more common as designers push the envelope for better performance and greater durability under very demanding conditions.
Fortunately, there are a number of alloys in the commercial mainstream that have proven themselves in these critical applications. At Ulbrich, buyers can obtain just-in-time deliveries when required and select from generous inventories covering more than 165 grades of stainless steel, nickel alloys, cobalt alloys and titanium and titanium alloys in a range of thicknesses, shapes, sizes and tempers.
Most of the fastener alloys in demand today are of the precipitation hardening variety. What makes them different from other grades of stainless and nickel-based alloys is the addition of small amounts of copper, aluminum, phosphorous or titanium to their matrix.
With these alloys, cold forming is done in the relatively soft solution annealed condition. After fabrication, the parts are given an age-hardening treatment in which the added elements precipitate as hard intermetallic compounds that significantly increase hardness and strength.
Because they are very similar, these alloys can often be used interchangeably depending upon their availability in the sizes, tempers and shapes required. In the case of strip, adjustments in metallurgy can be made through rerolling and heat treatment to arrive at the desired solution annealed condition.
Courtesy of Ulbrich.