What is the most recent turbofan engine that used steel for its bypass fan blades? I haven't been able to locate any engines that use steel for the bypass fan. All sources suggest Ti and composites are used for blade construction. Apart from the weight steel could partially make up for it by offering a thinner blade, cost/ease of construction and more resistance to foreign objects.
The reason I ask is that I am trying to design a large ducted fan (800mm) that will be as cheap as possible to manufacture by using a thin sheet of stainless steel for the blade material. The cut to shape sheet will be pressed in a mold to achieve the designed AoA across the blade length and then a 3D printed airfoil will slide over it.
The tickness of the Fan blade is not only defined by the structural requirement but rather for aerodynamic purpose, thus the geometry of the blade won't change much depending on the material used. Most of the metallic blades in use are hollow.
The price of the blade is quite irrelevent in modern engines. If you can decrease the wheight of the fan by 10% for double the price you'll do it as it will ensure so much fuel saving over the life of the engine. Thus I don't see the advantage of using steel over titanium for a fan blade.
Looking at other comments I understand it is for prototyping and needs to remain cheap. I would then recommend to build the core with 3D printed material which will give you the airfoil shape for aerodynamic and then enclose it with a metal sheets in order to obtain a sandwich like structure. This could greatly increase the stiffness and strength without much added weight.