Due to difficult pandemic situation with COVID-19 decease, as well as due to current geopolitical circumstances in the world, we are facing the shortage of steel and therefore the impossibility of delivering the contracted products within the agreed deadlines. It is thus necessary to find suitable steel for replacement. The procedure for selecting one such steel for substituting the deficit steel 25CrMo4,for the purposes of producing a responsible welded assembly, is described in this paper. After the careful analysis, the steel 42CrMo4 was taken into consideration as a possible substitute material. Prior to applying the new selected steel, it was necessary to perform the following tests: analyze its chemical composition, determine its most important mechanical properties and evaluate its weld ability. Then, the optimal welding and heat treatment technologies were determined, so that the quality of the responsible welded structure would meet all the requirements, as the structure made of originally used steel. For the new steel, all the mentioned and some additional tests were conducted and the appropriate welding technology was prescribed. To verify the selected technology, appropriate tests were conducted on the model welded samples, the results of which are presented in this paper. Based on the analysis of the obtained results, it was concluded that the 25CrMo4 steel can be replaced by the 42CrMo4 steel, however, with the mandatory application of appropriate supplementary measures.
Purpose: In this study, the effect of heat treatment on the microstructure and mechanical properties of 42CrMo4 steel were investigated. Design/methodology/approach: The samples were annealed at 860°C for 120 min. followed by oil quenching and then tempered at temperatures between 480 and 570°C for 120 min. The microstructure of untreated 42CrMo4 steel mainly consists of pearlite and ferrite whereas the microstructure was found to be as a martensitic structure with a quenching process. Findings: The results showed that there is an increase in yield stress, ultimate tensile stress, hardness and impact energy, while elongation decreases at the end of the quenching process. Conversely, yield stress, ultimate tensile stress and hardness decrease slightly with the increasing of tempering temperature, while elongation and impact energy increase. Research limitations/implications: Other types of steels can be heat treated in a wider temperature range and the results can be compared. Practical implications: It is a highly effective method for improving the mechanical properties of heat treatment materials. Originality/value: A relationship between the mechanical properties and the microstructure of materials can be developed. The heat treatment is an effective method for this process.
This paper presents the results of a numerical investigation into tube flanging by extrusion with a moving sleeve. Two cases of the extrusion process are investigated, each described with a different tool kinematics. Effects of flange diameter, gap height and tool motion on the extrusion process are examined. The numerical analysis is performed on 42CrMo4 steel tubes deformed at ambient temperature. Obtained numerical results are then used to determine metal flow patterns and examine force parameters in the extrusion process, as well as to determine a technological window for the investigated method.
This paper presents analysis of flank wear influence on forces in orthogonal turning of 42CrMo4 steel and evaluates capacity of finite element model to provide such force values. Data about magnitude of feed and cutting force were obtained from measurements with force tensiometer in experimental test as well as from finite element analysis of chip formation process in ABAQUS/Explicit software. For studies an insert with complex rake face was selected and flank wear was simulated by grinding operation on its flank face. The aim of grinding inset surface was to obtain even flat wear along cutting edge, which after the measurement could be modeled with CAD program and applied in FE analysis for selected range of wear width. By comparing both sets of force values as function of flank wear in given cutting conditions FEA model was validated and it was established that it can be applied to analyze other physical aspects of machining. Force analysis found that progression of wear causes increase in cutting force magnitude and steep boost to feed force magnitude. Analysis of Fc/Ff force ratio revealed that flank wear has significant impact on resultant force in orthogonal cutting and magnitude of this force components in cutting and feed direction. Surge in force values can result in transfer of substantial loads to machine-tool interface.
5
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
W artykule podano metodę porównywania struktur geometrycznych powierzchni SGP stali ze strukturą odniesienia żelaza armco na przykładzie procesu kulowania. Opracowanie wykonano na przykładzie porównania SGP stali 42CrMo4, z żelazem armco uzyskanych w takich samych warunkach obróbki.
EN
In this paper, a method was presented for comparing the surface texture of material obtained in the shot peening process with the reference texture of the Armco pure iron. The comparative investigation was carried out for the surface of the alloy steel 42CrMo4 and the Armco pure iron, while both materials had been treated the same way.
6
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW