Q: I’m looking to purchase some ¼-20 bolts/nuts/washers that will be suitable to fasten metal plate together at 1,300C. The fasteners need to last at least 4 minutes at this temperature but preferably longer. The load on the bolts will be very low.
A: I think there are a couple fast delivery options.
#1 – Inconel 600. Although this is limited in long term temp resistance to ~1100 C… The short time at temperature should allow it to perform OK. I’m sure 4 mins is OK. You may want to use a high temp anti-seize if these are disassembled often (https://www.extreme-bolt.com/store/anti-seize-lubricant/extreme-anti-seize-lubricant)
#2 – Ceramic. This material is exceptionally resistant to temperature and will have no problems at 1300C for long durations. However, ceramic screws are not as strong or tough as metals.