Being a QA, we learned a lot about the product, its customers and how to successfully create software. we probably had many ideas of how to make your team more productive. When we become a Scrum master, we will finally have time and resources to improve processes, optimize workflow, take overall responsibility of initiation, planning, design, execution, monitoring, quality assurance and closure of a project. Some of these overlap with your QA role so you can take advantage of your experience.
Last but not the least we should deepen our knowledge on Scrum framework and Agile values. Consider pursuing recognized certifications such as the Certified Scrum Master (CSM) or Professional Scrum Master (PSM),It would really have impact in the team effectiveness.