WRONG, A hardened piece of steels temper will start to change at around 350f, a knife is tempered to 400-450 to prevent edge chipping a spring is tempered to around 800f. You can make a piece of 1095 a file, a knife or a spring by the temper. In fact it is used both as files and as the cable on cranes. 4140 ordinance steel does not ever get that hard, but it will become dead soft long before it turns orange at 1600, and any useful temper is pretty much all gone when it starts to show red at about 1000f. Plus in the world of heat treating, steel frames would never be considered thick sections for that mater. Orange steel is hot enough to forge, and will start to experiences grain growth which WILL cause brittleness if not reset by normalizing.
Frames are not very hard. But, I doubt once they are normalized after forging, then hardened, they never get above 800f in the temper cycle
ANY heat treated piece of steel that is heated to the point of showing any iridescent color has had its heat treatment ruined and dependent on the heat treatment it may occur well before that.
I suggest reading the "Heat Treater's Guide" on 4140 and "Metallurgy Fundamentals"
But, unless the frame was right in the glowing coals or held for a period in the hottest part of the flame I doubt it got that hot. Take a metal rod and heat it in a camp fire. Unless you stick it right in glowing coal it is hard to get the steel to glow.
Thee reason I mentioned the springs is id they are still springs the frame never got much above 800f. Get a spring even a bit red hot and it is just a coiled up peice of wire.