The purpose of this diploma thesis entitled The Effects of strain rate on mechanical properties of PK11SP steel microalloyed with titanium was to determine the influence of strain rate on mechanical properties of PK11SP steel at the same chemical composition, initial forging/rolling temperature, deformation rate and the same heat treatment. PK11SP is an austenitic stainless steel, stabilized with titanium. The main purpose of titanium as a microalloying element is to prevent the binding of chromium and carbon and the formation of chromium carbides which would if the formation occurred form on the boundaries of the crystal grains and would have caused corrosion on the grain boundaries (intergranular corrosion). As input material we used an ingot of the same batch. We rolled the ingot into a billet and divided it into four pieces. Then every piece was processed with a different technological process. We used rolling (on the middle track), forging with a forging hammer and forging with a forging press. In all cases (all of four pieces) the initial temperature stayed the same. So were the final dimensions of the rods (35 mm in the diameter). The difference was only in the final temperatures and the strain rates. After production, the semi-finished products were quenched in water. From the semi-finished products, the specimens for mechanical tests were produced. The tests that have been performed were tensile test at room temperature, toughness test and Brinell hardness measurements were taken. At the end the grain size measurements were made with the use of metallographic techniques for determination of grain size. After the tests we concluded that the highest tensile strengths were obtained after strain rate 7 s-1. At the same strain rate we also obtained the highest values of toughness. At the strain rate 5 s-1 we obtained the highest values of yield stress, contraction, elongation and hardness.
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