Forging processing of steels is widely used. This method is used during pasta making. Therefore, it is not correct to think only about increasing the microhardness of the surface with the Forging method. At this time, the entire material is deformed.
Difficult to provide a precise answer to your question, however
Shot Peening is a controlled manufacturing process that involves bombarding the surface of a component with hard generally spherical shot (steel, ceramic, glass etc). The significant process parameters include the energy of the shot stream which is calibrated according to Almen Intensity (there are international standards that can be referred to) and the percentage of the original surface that is obliterated by indentations - termed coverage - this process will alter surface roughness, add residual stress to the treated surface and depending upon the parameters of the component and the energy of the shot stream, produce a permanent change in dimension of the component both in and out of plane. Shot peening is generally applied to improve corrosion and fatigue resistance.
Shot peen forming is a higher energy version of the above (larger ball sizes, lower coverage) and is used to impart shape to a component.
Blast cleaning, uses angular particles to remove surface contaminants, it too can produce changes in both microstructure and component dimension.