The paper presents research results on the selection of parameters for the asymmetric rolling process of bimetallic plates 10CrMo9-10 + X2CrNiMo17-12-2. They consisted in determining the optimum parameters of the process, which would be ensured to obtain straight bands. Such deformation method introduces in the band the deformations resulting from shear stress, which affect changes in the microstructure. But their effect on the structure is more complicated than in the case of homogeneous materials. It has been shown that the introduction of asymmetric conditions into the rolling process results in greater grain refinement in the so-called hard layer. There was no negative effect on the structural changes in the soft layer observed.
This paper presents the results obtained from the structural re.nement of selected metals and alloys produced by severe plasticdeformation processes. Large levels of deformations were produced using four methods, which di.ered in the character and dynamics of the loading, as well as in the intensity and homogeneity oft he plastic strain .eld. Qualitative and quantitative studies of the re.ned microstructure were carried out using stereological and computer image analytical methods. Microhardness and selected mechanical properties, such as strength and yield point, were also determined.
The development of the crystallographic texture in copper subjected to severe plastic deformation (SPD) by means of high pressure torsion (HPT) and equal-channel angular pressing (ECAP) was experimentally investigated and analyzed by means of computer modelling. It was demonstrated, that the texture developed in HPT and ECAP Cu is characterized by significant inhomogeneity. Therefore, the analysis focused on the study of the texture distribution and its inhomogeneity in sample space. The detailed texture analysis, based on the X-ray diffraction technique, led to important observations concerning the localization of the maximum texture gradient and the regularity of its changes related to the parameters of the applied deformation. The obtained results provided the basis for certain conclusions concerning complex texture changes in SPD Cu.
Two strength-age hardening aluminum-lithium alloys: Al-2.3wt%Li and Al-2.2wt%Li-0.1wt%Zr in two different heat treatment conditions: solution state (S) and additionally in aging state (A) were severely plastically deformed by rolling with cyclic movement of rolls (RCMR) method to produce ultrafine – grained structure. Two thermo-mechanical treatments were used: (S+A+RCMR) and (S+RCMR+A+RCMR). To investigate the combined effect of plastic deformation and heat treatment, tensile tests were performed. Microstructural observations were undertaken using scanning transmission electron microscopy (STEM), and scanning transmission electron microscopy (SEM) equipped with electron backscattering diffraction detector (EBSD). Based on the obtained results, it can be deduced that maximum mechanical properties as: yield strength (YS) and ultimate tensile strength (UTS) could be achieved when the microstructure of alloys is in (S+A+RCMR) state. For samples in (S+RCMR+A+RCMR) state, ductility is higher than for (S+A+RCMR) state. The microstructural results shows that the favourable conditions for decreasing grain size of alloys is (S+A+RCMR) state. Additionally, in this state is much greater dislocation density than for (S+RCMR+A+RCMR) state. The microstructure of alloys in (S+RCMR+A+RCMR) state is characterized by grains/subgrains with higher average diameter and with higher misorientation angles compared with (S+A+RCMR) state.
Microstructure and texture of the CuCr0.6 alloy processed by rolling with cyclic movement of rolls (RCMR) at room temperature were investigated. The RCMR processing was applied for the samples in different initial conditions in the solid solution followed by quenching into iced water at 1000oC for 3 h and in aging treatment conditions performed at 500oC for 2 h and at 700oC for 24 h. Application of the solution and aging processes prior to RCMR deformation results in the partial dissolution of Cr particles into the Cu matrix and precipitation of the second phase particles. RCMR processing with value of the total effective strain (εft) of 5 was introduced to the material. It was found that the RCMR method is effective in texture weakening. The obtained results revealed that there is a large similarity in texture orientations after RCMR processing independently of heat treatment conditions. Cyclic character of deformation leads to an incomplete transition of LAB to HAB.
The paper has presented the results of theoretical studies and experimental tests of the plastic deformation of multi-layered Ti/Al/Mg specimens. Theoretical studies were carried out using the Forge2011® computer program. Physical modeling, on the other hand, was performed using the Gleeble3800 simulator. Cuboidal specimens were cut off from the plates obtained in the explosive welding method. Based on the obtained investigation results it has been found non uniform deformation of the particular layer as a result their different value of flow stress.
In the present paper, the effects of the subsequent extrusion after multi-pass equal-channel angular pressing (ECAP) process on the mechanical properties and microstructure of WE43 magnesium alloy are investigated. First, second and fourth passes ECAP followed by an extrusion process are applied on WE43 magnesium alloy to refine the microstructure and to improve the mechanical properties for biomedical applications. The results showed that among the ECAPed samples, the highest and lowest strength were obtained in the second and the first pass processed samples, respectively. The four passes processed sample showed the highest elongation to failure with moderate strength. The sample processed via first pass ECAP followed by extrusion exhibits an excellent combination of ductility and strength. The highest strength was obtained in the sample processed via the second pass ECAP followed by extrusion while the highest elongation was achieved in the sample processed via fourth pass ECAP followed by extrusion. Moreover, Vickers micro-indentation tests demonstrate that hardness is enhanced by an increase in the number of ECAP passes. Furthermore, a grain refinement process is presented for ECAP processing of WE43 alloy which shows a good agreement with microstructural investigations.
This paper presents results obtained from a laboratory investigation conducted on material from a pressure vessel after longterm operation in the oil refinery industry. The tested material contained structural defects which arose from improper heat treatment during steel plate manufacturing. Complex tensile tests with acoustic emission signal recording were conducted on both notched and unnotched specimens. The detailed analysis of different acoustic emission criteria allowed as to detect each stage of plastic deformation and microstructural damage processes after a long-term operation, and unused carbon steels during quasi-static axial tension testing. The acoustic emission activity, generated in the typical stages of material deformation, was correlated by microscopy observations during the tensile test. The results are to be used as the basis for new algorithms for the assessment of the structural condition of in-service pressure equipment.
The paper gives an introduction to nanostructuring techniques used for industrial fabrication of bulk nanocrystalline metals basic materials utilized in shaping nanoscale structures. Nanostructured metals, called nanometals, can be produced by severe plastic deformation (SPD). We give an expert coverage of current achievements in all important SPD methods and present future industry developments and research directions including both batch and continuous processes. In the laboratories of both WUT and UOS we have developed industry standard equipment and machinery for nanometals processing. Utilizing the latest examples from our research, we provide a concise introduction to the field of mass production of nanometals for nanotechnology.
The samples of the CuCr0.6 alloy in the solution treated and additionally in aging states were severely plastically deformed by compression with oscillatory torsion (COT) method to produce ultrafine – grained structure. The samples were processed by using process parameters as: frequency of torsion (f = 1.6 Hz), compression speed (v = 0.04 mm/s), angle torsion (α = ±6°), height reduction (Δh = 7 mm). The total effective strain was εft = 40. The microstructure has been analyzed by scanning transmission electron microscope (STEM) Hitachi HD-2300A equipped with a cold field emission gun at an accelerating voltage of 200 kV. The quantitative microstructure investigations as disorientation angles were performed using a FEI INSPECT F scanning electron microscope (SEM) equipped with a cold field emission gun and a electron backscattering diffraction (EBSD) detector. The mechanical properties were determined using MST QTest/10 machine equipped with digital image correlation (DIC). The COT processed alloy previously aged at 500°C per 2h shows high mechanical strength, ultimate tensile strength UTS: 521 MPa and yield tensile strength YS: 488 MP attributed to the high density of coherent precipitates and ultrafine grained structure.
The article presents tests results of metalforming of magnesium alloy AZ61. Materials for tests were ingots sized 40×90 mm from magnesium alloy marked with symbol AZ61. Before the shaping process the ingots underwent heat treatment. As a result of conduction of the deformation processes there were rods achieved with diameter of 8 mm. There were axisymmetrical compression tests conducted on the samples taken from rods in temperature range from RT to 350ºC in order to determine the plasticity and formability of the alloy AZ61. Static tensile test was conducted in room temperature (RT), in 300ºC and in 350ºC. With the use of light and electron microscopy techniques the changes which occurred in the microstructure of AZ61alloy in initial condition and after plastic deformation (classic extrusion, KoBo method extrusion) were described. The deformation of alloy AZ61 using the KoBo method contributes to an increase in strength and plastic properties. The effect of superplastic flow was found at a temperature of 350ºC, where a 300% increase in plastic properties – elongation value was obtained. The analysis of the microstructure showed a significant grain size reduction in the microstructure of alloy AZ61 after deformation by the KoBo method and after an axisymmetric compression test, where grains of an average diameter of d = 13 µm were obtained.
The article reports the results of research on the influence of the alternate intermittent deformation of specimens by a torsion method on the Bauschinger effect in the Zr-1%Nb zirconium-based alloy. Tests were carried out using an STD 812 torsion plastometer. Based on the tests carried out, diagrams have been plotted, which represent the influence of the pre-deformation magnitude, the temperature of heat treatment prior to deformation, and deformation rate on the variation in the values of the flow stress and yield strength of the alloy under study. Conditions have been defined, in which larger magnitudes of plastic deformation of Zr-1Nb% alloy material can be used during its cold plastic working.
Mechanical properties of the pipeline samples that had been cut in annular and axial directions were investigated. The methodology of modeling and calculation of the real stress-strain state was described. The stable state during in the deformation process was defined. The results of the experimental researches were used as a test variant during examination of pipe strength.
In this paper, the author derives theoretical formulae for calculating of squeezing forces. This report is the first one concerning the method of forming stepped shafts by longitudinal cold rolling. The formulae of the radial squeezing forces for the final passage of longitudinal rolling were calculated under the Huber hypothesis of plastic deformation and maximum shear stress.