The paper presented the findings obtained by industrial research and experimental development on the use of rare earth metals (REMs) in the production of heavy steel ingots and their impact on the internal quality of the 42CrMo4 grade steel forging. REMs alloying was carried out after vacuuming the steel. A relatively large melting loss of cerium (about 50%) and its further decrease in casting due to reoxidation were observed. Refinement of structure and better mechanical properties of forged bar containing about 0.02 wt.% of Ce compared to that of the standard production were not achieved. The wind power shaft with content of about 0.06 wt.% of Ce showed high amount of REM inclusions, which were locally chained, and in some cases, initiated cracks. Four stoichiometrically different types of REM inclusions were detected in forgings, namely (La-Ce)₂O₂S + (La-Ce)O₂ + SiO₂ (minority); oxygen, phosphorus, arsenic, and antimony bound to lanthanum and cerium probably bonded with iron oxides La + Ce, MgO, Al₂O₃ a SiO₂; (La-Ce)₂O₂S, FeO, SiO₂, and CaO or CaS.

Significant structural steels for nuclear power engineering are chromium-nickel austenitic stainless steels. The presented paper evaluates the kinetics of the fatigue crack growth of AISI 304L and AISI 316L stainless steels in air and in corrosive environments of 3.5% aqueous NaCl solution after the application of solution annealing, stabilizing annealing, and sensitization annealing. Comparisons were made between the fatigue crack growth rate after each heat treatment regime, and a comparison between the fatigue crack growth rate in both types of steels was made. For individual heat treatment regimes, the possibility of the development of intergranular corrosion was also considered. Evaluations resulted in very favourable corrosion fatigue characteristics of the 316L steel. After application of solution and stabilizing annealing at a comparable ∆K level, the fatigue crack growth rate was about one half compared to 304L steel. After sensitization annealing of 316L steel, compared to stabilizing annealing, the increase of crack growth rate during corrosion fatigue was slightly higher. The obtained results complement the existing standardized data on unconventional characteristics of 304L and 316L austenitic stainless steels.

The prospects of processing blast furnace and steelmaking sludge using the Waelz process in a laboratory rotary kiln, is shown. The influence of different processing temperatures, furnace atmosphere and the type of reducing agents on the level of zinc reduction from sludges was analyzed. In general, the blast furnace sludge contains a high portion of iron (approx. 48 wt.%) and can be reused as a charge after satisfactory zinc reduction. It was found that N- atmosphere and a high content of the graphite or coke oven reducing agent in combination with high temperature can reduce the content of Zn in the sludge to 0.08 wt.% at 1200 °C for a mixture of steelmaking and blast furnace sludge. A significant reduction in the Zn content to 0.66 wt.% occurs at 1100 °C. The content and type of reducing agent plays an important role; graphite has shown a better reducing ability compared to coke oven dust. When nitrogen is used, zinc is reduced even without an additional reducing agent, since the carbon contained in the sludge is made use of for the reduction. In an air atmosphere, without the use of a reducing agent, there was no reduction in the Zn content.

In the aerospace industry, the nickel-based superalloys are often used due to their ability to withstand extreme conditions. They find their use particularly as turbine blades in jet engines. An important example of this type of superalloy is ...

The aim of this work is to compare the technological and material properties of CMnCr steels without bismuth, with 0.08 wt. % Bi and 0.12 wt. % Bi. Experimental heats showed that the most advantageous alloying of Bi into the heat was in the ladle, with an efficiency of about 20%. The optimal temperature range for forming steel was found to be 1160–1050 °C. With increasing Bi content, the formability of steels and plastic properties decreased, while the yield stress and tensile strength increased. Manganese sulfides, aluminum oxides, or oxysulfides, which were segregated both individually and in clusters, were found in the matrix of all tested steels. In steels with Bi, the Bi particles segregate the separately in the form of globules, either as envelopes of elongated MnS or Al₂O₃ particles segregated in rows. Sulfur dot-shaped segregations in the steel with 0.12 wt. % of Bi and the steel without Bi were essentially uniform over the whole area. For the steel with 0.08 wt. % of Bi, both dot-like and ray-ordered sulfur segregations were observed. The microstructure of all tested steels was ferritic–pearlitic with islands of bainite. Towards the center of the forged bars, variable shape and size of bainite blocks were observed. Machinability tests evaluated by the extend of tool wear showed that the most advantageous was CMnCr steel alloyed with 0.08 wt. % Bi.

The aim of the work was to evaluate the hot ductility loss in TiNb stabilized IF steel directly from the continuously-cast slab using hot torsion testing (plastometry) in the temperature range 600–1250 °C according to the basic programme, and also after temperature cycling. A good match of the temperature dependences of number of turns to failure (N_f) and intensity of deformation S_e was confirmed. In both cases, the existence of three temperature areas with decrease in plasticity to a minimum was confirmed. The two-stage temperature cycling according to the CT1150 and CT900 programmes mostly resulted in a decrease in plasticity compared to the basic programme. The most significant effect of cycling was related to the CT900 programme below the maximum plasticity in the base programme at 850 °C. A less pronounced decrease was observed for CT1150 cycling below the maximum plasticity in the base program at 1050 °C. In the case of CT1150 cycling, more complex particles were observed at the fractures compared with the basic programme, namely carbonitrides of Ti and Nb in combination with oxisulfides respectively, then Ti nitrides with oxisulfides or oxides and, in addition, complex (Fe,Nb)P₄, (Ti,Nb)₃S₄ type particles. Their mean size determined statistically using TEM was much finer, only 20 nm versus 42 nm in the basic programme. Similarly, CT900 cycling revealed finer particles with an average size of 37 nm compared to 105 nm in the basic programme. The observed particles were Al oxides, Ti(N,C) and (Ti,Nb)₂S, in contrast to the particles probably of TiFe and FeMnS in the basic programme. The decrease in plasticity corresponded to the finer particles, newly created in the temperature cycling.