The aim of the examination is to show the effects of these position errors, and compare the properties of PA flat positioned fillet welding. The different gaps replace the different sized position errors. We study the effect of these welding defects. We cut samples out from the weld pieces, and made microsection. Through this we examined the formal effects and geometric incompletion of the weld. On polished and etched section the meltdown depth is turning into measurable the thermal effect area into visible, which we measure with hardness tester machine.
In this overview, the results published to date concerning the development, processing, microstructure characteristics, and properties of silicon nitride/carbon nanotube (Si3N4 + CNTs) composites are summarized. The influence of the different processing routes on the microstructure development of the Si3N4 + CNTs is discussed. The effects of the CNTs addition on the mechanical properties—hardness, bending strength and fracture toughness—and tribological characteristics—wear rate and coefficient of friction—are summarized. The characteristic defects, fracture origins, toughening and damage mechanisms occurring during the testing are described. The influence of the CNTs’ addition on the thermal and functional properties of the composites is discussed as well. New trends in the development of these composites with significant potential for future applications are outlined.
Specimens of austenitic stainless steel hardness changing were tested. The used hardening technology was a modified explosive treatment. During the hardening tests the explosive exploded different distance from surface. Same setup was tested with 2, 3 and 4 mm holder. The hardness improving and the plastic deformation were different as function of the holder size. The hardness was measured by Vickers hardness tester. The amount of strain induces martensite was detected magnetically. It can suppose that the microstructure changed during high rate strain. Results showed that the strain rate and result hardness depend on the holder size. We found that the bigger holder size in case of the tested setup provoke higher hardening. To determine the hardness properties it’s important to use an optional setup.
It knows that between the grain size and the mechanical properties can find relation [1]. The Hall−Petch equation shows a relationship between the grain size and the yield strength. This equation valuable in case of low carbon steels. Also in the literature we can find a linear function to numerate the yield strength from the hardness. We made some welding samples and measured the hardness and the grain size in the welded joint and the heat affected zone. We find a strong correlation between the grain size and the hardness in case of the tested steel. We supposed in base of our results that we can find a correlation between the grain size and the yield strength too. The hardness test is very quick and simple test what we use always to control the quality of the welded joint and the heat affected zone. If our supposition is real and we can find a correlation between the hardness and the yield strength it can be very usefully during the design of the welding technology.
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