If applying for visa in the sds category, you need to have overall 6.5 with no module less than 6. Otherwise, you won't qualify for it and will have to apply via general category. Even in general category, visas are refused in most cases because the vo might doubt about your ability to understand or communicate in English. Not saying its impossible to obtain a visa, but there is a very slim chance of getting it. It totally depends on the mood of the vo and your luck to get accepted with scores below than 6 bands. If possible, take the ielts again and try to get atleast 6.5 in each module.