Due to the fact that the annual amount of plastics is increasing, the amount of plastics, built through injection moulding, is increasing, too. Not only is there an enormous increase of technical demands, but also of economic demands. Indeed, more and more additives are used in plastic injection moulding; additionally, this has an effect on the wear of injection moulding machines. Materials are needed to compensate high downtimes to meet the economic requirements. A specific appliance for process simulation was used to mould a Polyamid 6.6 with 50mass% fibreglass to investigate wear. With higher volumetric flow wear plates showed an increasing softening. The wear plates, which consits of X190CrVMo20-4-1 steel, limited a tight wear gap, where the polyamid was moulded under high pressure and temperature. To understand the processes in its microstructure the used wear plates were characterized via light microscope, scanning electron microscope, and hardness testing. Dilatometer experiments were used to recreate the thermal load on X190CrVMo20-4-1. Near-surface softening is shown in the wear plates, as well as a decrease of corrosion resistance. As a matter of fact, the softening and the decrease of corrosion resistance in the wear plates is linked to a coarsening of the secondary hardening carbides which are present in the steel.