Can alloy steel seamless pipes be used as hydraulic cylinder barrels?

It depends on whether the cylinder you make has any special requirements! Such as pressure, working conditions, etc.!

It is best to use high-quality carbon steel for pipes, 45# or 27SiMn. 27SiMn is better, both in terms of mechanical properties, processing and welding performance. Our company's current cylinder barrel materials are generally 45# cold drawn pipes and 27 SiMn!