The　transformation　behavior,　mechanical　properties　and　stretch-flangeability　of　an　ultra-high-strength　TRIP-assisted　bainitic-ferritic　sheet　steel　0.2C-2Si-1.8Mn　were　investigated　at　different　austempering　temperatures　for　automotive　applications.　Increasing　the　austempering　temperature　was　found　to　partially　transform　the　uniform　fine　lath　structure　matrix　and　film-type　metastable　retained　austenite　into　blocky　martensite　or　austenite.　The　investigated　steel　exhibits　good　stretch-formability,　particularly　when　austempered　at　temperatures　lower　than　or　slightly　higher　than　the　M-s　point,　accompanied　by　an　excellent　combination　of　strength　and　ductility.　The　good　stretch-flangeability　is　related　to　a　certain　number　of　film-type　metastable　retained　austenite　structures.　Blocky　martensites,　which　blocky　austenite　transforms　into　during　the　cooling　process　or　subsequent　tensile　test,　deteriorate　the　stretch-flangeability.　(C)　2014　Elsevier　B.V.　All　rights　reserved.