Solid State Phenomena Vol. 226

Abstract: This paper presents the results of dynamic deformation tests performed on aluminum alloy PA4. The studiem was carried out by using rotary hammer, in the range of high rate of deformation: 400 – 2000 s^-1. The test were carried using a rotary hammer of RSO type owned by Silesian Technical University in Institute of Technology Metals. Before the dynamic deformation, the heating treatment was carried out allowed for eliminating structural effects resulting from the previous technological treatments and for obtaining the homogenous grain structure. The tests were carried out with linear velocity in the range of 5 – 30 m/s. After deformation the following mechanical characteristics were determined: deformation limit ε_g, strain rate , tensile strength UTS, impact strength U. Independently of the dynamic deformation tests were carried out tensile test under static conditions. Moreover bending test were performed on Charpy type hammer with initial impact energy equal 300 J. The analysis of the microstructure was carried out using scanning electron microscopy Hitachi S–3400 N.

Abstract: The article discusses the mathematical and practical methodology for evaluating the temperature on the surface of bimetallic wire after deformation in the drawing die. The components of bimetallic wire on the cross-section are the following materials: - a core, brass M63 (CuZn37) - shell M1E copper (Cu – ETP), - a core, aluminum Al (A199, 5) - shell M1E copper (Cu – ETP). An outer layer (shell) in such combinations is always a copper with two different thicknesses of 1.5 mm and 0.5 mm, which means that the proportion of copper on the cross section of the bimetal was respectively 64% and 32%. The bimetallic wires samples used for measurements were obtained by mechanical cladding. In the first step of the process, the cooper tubes M1E were put on the aluminium and brass wires M63, and then in a second step, each set combination was subjected to a simultaneous deformation with a total true strain φ_lc ~ 1. Thus obtained the bimetal wires were the blank material for determining the surface temperature. In the drawing process there were used two different drawing speeds, and for each was applied the two individual size of deformation of 15% and 30%. The temperature on the surface of the layered wire depending on the single deformation and drawing speed was determined using a thermographic camera and it was also calculated according to mathematical formulas. The article discusses the preliminary results necessary to conduct further deliberations on the temperature decomposition on the longitudinal section of the bimetallic wire deformed in the drawing die.

Abstract: Alumina materials are widely used in the industry as cutting tool inserts. In order to improve mechanical properties of the Al₂O₃ matrix, different reinforcing phases are introduced. In the presented work, reinforcements in the form of ZrO₂ particles and SiC nanofibres have been used. ZTA-SiC composites were obtained from 0.5%MgO-20%(3Y₂O₃)ZrO₂-79.5%Al₂O₃ powder and 15% of SiC whiskers. Tested materials have been prepared by means of the two-step sintering (TSS) and spark plasma sintering (SPS). TSS method permits to obtain dense materials with fine-grained microstructure. TSS has been carried out for two different sintering times: 1 hour 20 minutes and 8 hours. Due to the reactivity of the components, the SPS method has been used to shorten sintering times. SPS has been performed at two different temperatures: 1500 °C and 1550 °C.

Abstract: The paper presents the characteristics of a new generation of austenitic stainless HR3C also used on items of equipment operating at elevated temperatures. Changed welding technology and the results of metallographic and mechanical properties of joints. Developed and implemented welding technology made it possible to obtain high-quality connectors, the correct construction of the required structural and mechanical properties.

Abstract: The paper presents the results of investigations of the microstructure and fatigue behaviour of two newly invented Cr-Ni and Cr-Ni-Mn austenitic steels of 13/13 and 12/8/8 type strengthened through carbide particle precipitation. The specimens of the investigated steels were subjected to tests after heat treatment, i.e. solution heat treatment (1200°C/0.5 h/water) and aged at a temperature of 700°C for 12 h, with cooling in air. The heat treated specimens were then subjected to low-cycle fatigue tests (LCF), carried out at room temperature and at an increased temperature of 600°C. Diagrams of fatigue characteristics of the investigated steels at room temperature as well as at elevated temperature have been worked up. It has been found that during low-cycle fatigue tests, at both temperatures, the investigated austenitic steels indicated a fatigue softening effect. The results of LCF at room temperature showed that the fatigue durability (N_t) of both austenitic steels is located in the range 0.8÷1.3×10³ cycles. The results of low-cycle fatigue tests at an increased temperature 600°C indicated that the fatigue durability of the investigated steel was lower, and is located in the range N_t = 0.5÷0.6×10³ cycles. It has been pointed out that the investigated austenitic steels are characterized by a stability of structure in conditions of cyclic fatigue.

Abstract: New generation high-strength austenitic and austenitic-ferritic manganese steels represent a valid potential in applications for components in the automotive and railway industry due to the perfect combination of high mechanical properties and formability. Applying this new steels with their combination of properties allows for reduce the weight of vehicles by the use reduced cross-section components and thus to reduce fuel consumption. The development and implementation of industrial production and the use as construction materials such interesting and promising steel is conditioned to improve their casting properties and susceptibility to deformation during thermomechanical processes conditions. In this work, applied an new high manganese austenitic-ferritic steel for analysis the influence of the cooling medium in thermomechanical processes on the mechanical properties and structure of researched steel. The steel was hot rolled with finish temperature 900°C and next cooled with different conditions. Change the cooling conditions effect on the changes in the microstructure of the tested steel, observed grain refinement of austenite and ferrite morphology change. Also are changing the mechanical characteristics of the tested steel.

Abstract: The paper contains the results of theoretical and experimental research on tube bending process used in manufacturing of 14MoV6-3 steel tubes. The innovative tube bending process using local induction heating and the results of finite-element numerical analysis of tube bends using Symufact Forming 11.0 software were presented. Numerical analysis covered the changes in pipe bend geometry (ovalization of cross section, wall thickness) and the results were compared with those obtained in industrial conditions. Basic mechanical properties of bended tube (diameter 323.9 mm, wall thickness 40 mm) in the supply condition and after heat treatment were determined using tensile, hardness, impact, low-cycle fatigue and creep tests. It has been shown that 14MoV6-3 steel tube bends manufactured using proposed technology meet the requirements of the PN-EN 10216-2 standard.

Abstract: 7CrMoVTiB10-10 (T24) steel was designed for high temperature applications, especially for water wall panels in modern supercritical coal-fired boilers. However, welding of T24 steel caused many problems due to its cracking susceptibility. In the present paper the causes of T24 steel weld joints cracking have been discussed. Microstructural and fractographic analysis of weld joint were conducted and hardness was measured. It was found that the main causes of crack’s formation in weld metal are hot cracking susceptibility of T24, high deformation during welding process and weld metals’ hardenability. The mechanism of cracking was determined. It was concluded that cracks had been initiated in high temperature brittleness range, then propagated through the weld metal in transverse direction as the cold cracks. The reduction of weld metal’s ductility was due to too high cooling rate and excessive hardening of weld metal in relation to base metal.

Abstract: Zn-Al alloys are mainly used due to their tribological properties as an alternative material for bronze, cast irons and aluminum in a bearings and as a construction material. Particular interesting is Zn-40Al-3Cu alloy due to its features. Improvement of the alloy’s features can be obtained by silicon addition, plastic working, heat treatment – solutionizing and ageing. In the article have been shown results of the ZnAl22Cu3 alloy examination as - cast and subjected solutionizing and ageing 385 ^oC/10h + 175 ^oC/1h and 385 ^oC/10h + 175 ^oC/10h. The scope of examination included: structure testing using scanning microscope, X - ray microanalysis, hardness test. There was found significant decrease of hardness of the tested alloy. Structural examinations have shown that initially in the structure were visible precipitates reach in aluminum and copper. Also were visible precipitates reach in zinc. With increasing time of soaking at 175 ^oC precipitates reach in aluminum and copper disappeared.

Abstract: Defining the susceptibility to hot cracking of Inconel 617 alloy welds is essential for assessment welding and pad welding technology. Because of that technological transvarestraint test was performed in the study. Test simulates strains that form in the material during welding. Transvarestraint test enables the assessment of susceptibility to hot cracking and resistance to hot cracking characterized by cracking threshold (ε_p) and critical strain speed (CSS). Performed investigations enabled to characterize the phenomena occurring in Inconel 617 during welds crystallization, which are important for engineers selecting the joining technology of Inconel 617.