Joshua made a solid start and led by two after the first, but began to dominate proceedings as they entered the second.
A massive right hand shook Zhang as he stepped in to launch an attack, sending him crashing to the canvas. It took a while for him to clear his scrambled senses.
Joshua was well ahead by the third bell and was content to see out the victory. However, he still landed a few decent scoring shots on his opponent.
In the end, the home-crowd favourite progressed 15-11.