An aim of a research was to determine the reasons of fracture of aluminium alloy components used for spinning of chemical fibres and to improve spinning process by selecting material with better performance.
Author: Kandrotaitė Janutienė R.
TRANSPORT TECHNICS. INVESTIGATION OF ELEMENTS. RELIABILITY
Analysis of PowerCore automotive air filter was made and development of new alternative air filter was performed by increasing surface area of filtering material. New shape of construction of air filter was suggested by introducing double-layer filtering material. It was determined that effective surface area of the new design of air filter was increased 1.5 times comparing with the patented PowerCore item of the same size. Efficiency and strength of the new design air filter was evaluated calculating air flux rates, deformations and displacement in SolidWorks environment.
INFLUENCE OF CHEMICAL COMPOSITION OF TOOL STEEL ON PERMANENT PLASTICITY DURING HEAT TREATMENT TRANSFORMATIONS
The work presents the research of permanent strain occurred when metallurgical transformations take place even under small stress applied externally lower than the yield stress of weaker phase. Four tool steel grades were tested: THG2000 (Uddeholm, Sweden), 20X13, 40X13 and 95X18 (GOST). All steel grades differ in carbon content and amount of alloying elements and behave differently when transformation plasticity occurs. This phenomenon was observed during bending test when bending stress was 100MPa and was less than 10 % of yield strength of the steel. The steel specimens were heated to 950-1050 °C temperature and then bent during air quenching. Plastic deflections were observed though all cooling process that involved martensitic transformation as well. Different effect of compression and tensile stresses on microstructure evolution during martensitic transformation was determined as both type of stresses formed in bent specimens.
The article deals with the investigation of plastic deformations of carburized medium carbon stainless steel after quenching and tempering. After carburization the specimens were heated at 1020 °C temperature and then air quenched. At the process of air quenching the specimens were bent within the temperature dropping interval approximately from 550 °C to room temperature. The bending caused tension or compression in different parts of the specimen, so interstitial distortion was formed. As the bending stress was much lower than the yield stress, the specimen didn’t bend during the first minutes of experiment, and then started bending during the martensitic transformation (transformation plasticity effect). The curved quenched specimens then were tempered at temperatures 200, 300, 400, 500, 600 and 700 °C for 1 hour and the deflection of specimen after each tempering was measured.
The results showed different influence of tension and compression on transformations occurring in steel during quenching and tempering. The tempering temperature effect on self-deformation of curved specimen was revealed.