Adding to Deeko's comment:
Preload is tensile in the bolt and compressive in the clamped flanges. When external load is applied, the ext load is carried by both, proportioned by the relative stifnesses. Upon joint separation, there is zero compressive load in the flanges and all of the preload...
That sounds like the old designations for aluminum alloys. The modern designation would be 2024-T4. The A-250 type number would be a procurement spec. Check stinet.dtic.mil and search for QQ-A-250 and its slash sheets for specific forms and alloys. QQ-A-250 is the current Fed Std for general...
Check the small/odd parts bins in the hardware aisle of a Home Depot or Lowe's. I have seen replacement parts of the type found in knock-down type furniture kits there. Also check web and mail order firms that sell hardware for woodworking or ads in the back of a magazine such as Fine...
