According to researched information, exposure of the bushings to temperature up to those listed below should not cause any appreciable change in material strength characteristics:
Steel - 850 F
Ductile Iron - 800 F
Sintered Steel - 800 F
Gray Iron - 750 F
Malleable Irons - 700 F
Our standard grade 5 capscrew would not be appropriate for se. The customer is responsible that a like material is used in the mating components.
Information sources for the above listed bushing materials were: a sintered steel consultant the Iron Castings Handbook, 1983 published by Iron Castings Society, Inc.; Metals Handbook Tenth Edition, Properties and Selection: Irons, Steel, and High-Performance Alloys, 1990 published by ASM International and High-Temperature Property Dats: Ferrous Alloys, 1988 published by ASM INternational.