Originally Posted by tinkybelle

From past dealings with Qantas I would say they would not be responsible nor would they honor an expired ticket as Qantas did not issue the connecting ticket.
had they isued the connecting ticket with a note that you were connecting you would have a better chance.
Qantas do NO favours

Agree. Also do note that because it is seperate tickets, hence it is seperate contracts. There are no obligations on AY or QF to do anything. BUT if AY did issue both the boarding pass (AY and QF) then QF might be able to rebook you on the next flight without looking at the ticket. But it is risky stuff.
Can't you do the AY sector 1 day earlier to ensure you do get on the QF flight?
Also given it is B Class, you might be able to get some refund??