I am reading the quotes and cites as follows:
For some steels the Colder the Steel the more it would bounce.
For Harder steels the difference is minimal.
Does that sound true?
Jim
Please report to a punishment center.
That’s absolutely correct - at least, that’s what my cite says. 
Thank you. I ‘bounced’ all this information of the two Engineers and they agree with the findings. The one is less than a year out of College and so his Physics is fresh.
I think the jokes can commence now in safety barring any major new revelations.
Jim
From what I can tell, yes, the harder the type of steel the less impact temperature change will have.
As the metal gets hotter, it becomes softer and will lose more energy with each bounce. As it gets colder though, it becomes more brittle and will again start to weaken and lose more energy with each bounce. It probably doesn’t start to get brittle until -100 celcius or -300 or something amazingly cold though. So my guess would be that around the 30 to 120 degree Farenheit scale, probably the colder ball will bounce better. In the -300 to -400 though, the hotter might instead.
And again, yes, this will depend on the quality and hardness of the steel, and the curve of where the coefficient of restitution is may not be related to any meaningful equation, since the metal may undergo various minor chemical changes at varying temperatures. (for instance, the coefficient of restitution for water probably doesn’t change all that much between negative 40 and negative 80 degrees Celsius, but between negative 30 and positive 10 it’s going to change quite a lot!)