Last year IIT Dhanbad's cutoff for branch change to CSE was 9.3. However, I will suggest you not consider joining any colleges solely based on your branch change.
One of my friends was about to make a similar decision when he got Vil at IIT Kanpur. However, seniors dissuaded him from joining the college just for branch change. This is because branch change is very unpredictable and might ruin your future. It's advisable to check the first-year course before considering branch change.
Branch change might be easy for some while very challenging for others.So, I will suggest you never be fully dependent on department change. Always check the content of the branch before making the final choice.