Determination of the fracture mechanics properties on FSW welded joint

Cilj moje diplomske naloge je bil, da ugotovim, katere od treh hitrosti varjenja po varjenju z gnetenjem imajo najboljše mehanske lastnosti in najboljšo mehaniko loma ter v katerem območju vara (istosmerno, sredina, protismerno) so najboljše lastnosti. Var in osnovi material smo preizkušali po treh preizkusih. Prvi preizkus je bil natezni preizkus, pri katerem smo testirali osnovni material in var. Rezultate smo med seboj primerjali in ugotovili, da ima najboljše lastnosti osnovni material ter s tem potrdili naša predvidevanja. Drugi preizkus je bil preizkus udarne žilavosti (Charpy kladivo) pri sobni temperaturi. Imeli smo preizkušanec iz osnovnega materiala in iz treh delov vara. Udarna žilavost je bila največja pri osnovnem materialu. Iskali smo tudi, katera od treh hitrosti varjenja (A,B,C) se bo s svojimi lastnostmi najbolj približala osnovnemu materialu. Hitrost B je dala v povprečju najboljše rezultate pri udarni žilavosti in se je najbolj približala osnovnemu materialu. Zadnji preizkus je bil ASTM E1820, kjer smo preverjali, kako dobro se material upira širitvi že nastale razpoke. Preizkus je potekal v treh glavnih korakih: utrujanje, širjenje razpoke in utrujanje do zloma. Pri vsakem koraku smo zabeležili podatke, ki so nam podali končno sliko. Zmerili smo tudi razpoke, ki so nastale v drugem koraku. In na podlagi zbranih podatkov določili, katera od hitrosti se je najbolje obnesla. Najboljše lastnosti je v povprečju dosegla hitrost B. Končni sklep je bil, da ima plošča B najboljše lomno mehanske lastnosti.The aim of my thesis was to find out which of the tree speeds (A,B,C) gave me the best results on mechanical properties and fracture mechanics. And in which the sealing zone (in the same direction, centre, opposite) are the best features. Weld joint and the basis of the material was tested in three trials. The first test was a tensile test, in which we tested the base material and weld joint. The results were compared with each other and found that the best properties belong to base material, thus confirming our prediction. The second test was a test of impact strength (Charpy hammer) at room temperature. We had a specimen from the base material and three parts deceiving. Impact toughness was the largest in the base material. We were looking for a one of three welding speeds (A, B, C) will be with their properties closest to the base material. The speed of B has given us an average of the best results in terms of impact toughness and is closest to the base material. The last test was ASTM E1820, which we examined how well the material resists the expansion of cracks. The experiment was carried out in three main steps, fatigue, crack propagation and fatigue to fracture. At each step, we recorded information that we give a final image. We measured the cracks that occurred in the second step. And based on the collected data to determine which of speed performed the best. Best properties reach an average speed B. The conclusion was that the best fracture mechanical properties of the plate