The paper presents the research results on duplex corrosion-resistant chromium–nickel–molybdenum cast steel of the GX2CrNiMoCuN 25-6-3-3 grade. The aim was to determine the effect of the soaking temperature for the hyperquenching process Tp, that is, 950 to 1200 °C, on the microstructure and mechanical properties, that is UTS tensile strength, the yield strength, HB Brinell hardness, the elongation EL and impact strength KV of the steel, cast under industrial conditions with the minimum content of Cr, Ni, Mo and Cu according to the PN-EN 10283 standard. On the basis of the results, it was confirmed that the hyperquenching guarantees the elimination of the brittle intermetallic phase in the steel microstructure. In addition, the most favorable strength-to-ductility ratio of the steel with an almost equal amount of austenite γ and ferrite α in its microstructure was obtained using the soak temperature of 1080 °C, which was considered optimal for the above-mentioned duplex cast steel.

The paper presents the research results of the influence of the precipitation hardening on hardness and microstructure of selected Al-Si and Al-Cu alloys obtained as 30 mm ingots in a horizontal continuous casting process. The ingots were heat treated in process of precipitation hardening i.e. supersaturation with subsequent accelerated or natural ageing. Moreover in the range of the study it has been carried out investigations of chemical constitution, microscopic metallographic with use of scanning electron microscope with EDS analysis system, and hardness measurements using the Brinell method. On basis of obtained results it has been concluded that the chemical constitution of the investigated alloys enables to classify them into Al alloys for the plastic deformation as EN AW-AlSi2Mn (alternatively cast alloy EN AC-AlSi2MgTi) and as EN AW-AlCu4MgSi (alternatively cast alloy EN AC-AlCu4MgTi) grades. Moreover in result of applied precipitation hardening has resulted in the precipitation from a supersaturated solid solution of dispersive particles of secondary phases rich in alloying element i.e. Si and Cu respectively. In consequence it has been obtained increase in hardness in case of AlSi2Mn alloy by approximately 30% and in case of AlCu4MgSi alloy by approximately 20% in comparison to the as-cast state of continuous ingots.