The stress process samples undergo during the intense pulse ion beam (IPIB) irradiation and sequent fast cooling is one of the most important effects of IPIB. It can change the microstructure and microhardness of the samples. By comparing thermodynamic calculation with the experimental results of microhardness measurements for 45# steel samples and pure Al samples which are irradiated by IPIB at different energy fluence

we suppose that the generation

propagation and reflection of stress wave should account for the phenomenon of multi-maximum of microhardness. The experimental results also proved our deduction about the microhardness maximum appearing at a certain depth near the back side surface.