Pengaruh Perlakuan Termomekanis Terhadap Sifat Mekanik dan Korosi Paduan AZ31B dalam larutan Simulated Body Fluid (SBF) Sebagai Implan Biodegradable = The effect of thermomechanical treatments towards the Mechanical and corrosion properties of AZ31B alloy in Simulated Body Fluid (SBF) as a biodegradable implant