The current study focusing on investigating the mechanical properties of joining two dissimilar pieces of Austenitic stainless steel AISI304 and Low carbon steel ST-37 using rotary friction welding techniques. The metals were welded under different rotational speeds 560, 1030 and 1800(RPM) with varying friction time at each rotational speed.The tensile test, impact test, micro hardness distribution and microstructure examination of the welded specimen were carried out. At rotational speed 560(RPM) with forging pressure 65(Mpa), the tensile strength increasing when the friction time increased until reach to value 567(Mpa) at friction times 15, 20 (sec) then decreasing in tensile strength with increasing friction time.While at rotational speed 1030(RPM) with forging pressure 45(Mpa), the tensile strength increasing when friction time increased. While at rotational speed 1800(RPM) with forging pressure 80(Mpa), the tensile strength decreasing when friction time increased, until reach 551.5(Mpa) at friction time 9(sec) then increasing in tensile strength with increasing friction time. The maximum tensile strength was 596.3(Mpa) achieved at a rotational speed of 1030(RPM) with joint efficiency 93.8%. The hardness increases with increasing friction time at the weld zone.The impact energy decreasing when the friction time increased.