Abstract
Selected problems with the weldability of higher-strength steels, high-strength steels and martensitic copper-precipitation-hardened stainless steels, which were solved by the Physical Metallurgy and Powder Metallurgy Department at the AGH University of Science and Technology, are presented in the article. It was pointed out that the formation of M-A islands in welded structures results from too-slow cooling after the welding process, and is the reason why the welds and the heat affected zones (HAZs) have such a low impact. Testing of copper-based precipitation hardening of martensitic stainless steel demonstrated that fractures occurring in the HAZ were of the hot fracture type, and result from the steel's surface having been enriched with copper.