In the article, the structure and selected mechanical properties of welded Hardox 600 steel are presented. It is shown that, after welding of this material in as-delivered condition (i.e., with post-martensitic structure), structures of lower wear resistance are created within heat-affected zones. These zones are over 80 mm wide, which makes them susceptible to uneven and fast wear in their intended applications. On the grounds of microscopic tests and hardness measurements, a thermal treatment of welded joints is suggested, consisting of quenching and low-temperature tempering of heat-affected zones. As a result of this treatment, the material structure in these areas becomes similar to the base material structure. Under laboratory conditions, the performed heat treatment does not cause any incompatibilities (cracks) in the welds.