Bainite at room temperature? I read that if, after a tempering from T>723°C to T*=[250°C,550°C], I do an isothermal transformation of an eutectoid steel, I'll get bainitic microstructure.

Does this microstructure exist only if temperature remains at T=T* also after microstructure was formed?

In other words, if I do a cooling until room temperature (after bainite was formed), will it exist at this temperature?

Thank you very much.
The microstructure is retained upon cooling. After bainite forms, you can even quench it and it will remain bainite. The only way to get martensite is to cool it so fast that bainite has no time to form. The only way to get bainite is to cool it so fast that bainite can form, but not so fast you get martensite, and not so slow that you get pearlite. After the microstructures have formed, they remain, unless you reheat it.