Here is the list of fastest ODI hundreds for Australia.
The record is currently held by Glenn Maxwell with James Faulkner and Steve Smith coming in at No 2 & 3 respectively as seen in the graphic below. Smith has hit a 62 ball 100 TWICE in Australia’s 2020/21 ODI series against India, both at Sydney (November 27, 2020 and November 29, 2020)