Vpliv oblike preizkušancev na rezultate nateznega preizkusa

Krajnc, Nejc (author)

Namen diplomske naloge je preučiti, kako hitrost raztezanja ter oblika preizkušancev vplivata na rezultate meritev nateznega preizkusa. Standard DIN EN ISO 6892-1:2016 za natezni preizkus namreč dopušča testiranje preizkušancev različnih oblik ter pri različnih hitrostih raztezanja. Iz vroče valjanih palic jekel VCNMO200 in PK323MO smo izdelali različne standardizirane oblike nateznih preizkušancev. Vsi vzorci so bili izrezani prečno na smer valjanja ter na enakih mestih. Meritve smo izvajali v dveh neodvisnih laboratorijih. Uporabili smo natezne stroje različnih proizvajalcev, menjali izvajalce meritev, spreminjali hitrost raztezanja in obliko preizkušancev ter primerjali rezultate meritev. Za ugotavljanje vpliva hitrosti raztezanja na rezultate nateznega preizkusa smo preizkušance obremenjevali s tremi različnimi hitrostmi in sicer v razponu od 6 MPa s-1 do 60 MPa s-1. Za ugotavljanje vpliva oblike preizkušanca na rezultate nateznega preizkusa pa smo različne vrste preizkušancev natezno obremenjevali pri enaki hitrosti in sicer 30MPa s-1. Rezultate meritev smo zbrali v tabeli in jih analizirali ter rezultate grafično prikazali. Ugotovili smo, da hitrost in oblika preizkušancev vplivata na rezultate nateznega preizkusa, vendar je vpliv minimalen. Poleg tega je bila minimalna tudi razlika v rezultatih pridobljenih z različnimi napravami za izvajanje nateznega preizkusa, toda le v primeru uporabe naprav s kontroliranimi parametri izvajanja preizkusa.

• Language: Slovenian
• Keywords: natezni preizkus, hitrost obremenjevanja, oblike preizkušancev, jeklo PK323MO, jeklo VCNMO200, natezni stroj
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2018
• PID: 20.500.12556/RUL-103951
• COBISS.SI-ID: 1771103
• Publication date in RUL: 29.09.2018

Secondary language

• Language: English
• Title: Influence of the shape of specimen on the results of tensile test

Abstract

The purpose of diploma thesis was to study, how the stress rate and the shape of specimen influence the results of tensile test. Namely, the DIN EN ISO 6892-1:2016 standard for metallic material tensile testing permit execution of a test at various stress rates, and various specimen shapes. Various standardized forms of specimens were manufactured from the hot rolled rods of the VCNMO200 and PK323MO steels. All specimens were cut transversely to the direction of rolling and at the same positions. Measurements were carried out in two independent laboratories. Results are compared and represented according to various tensile testing machines, operators, stress rates and specimens shapes. In order to determine the influence of the stress rate on the results of the tensile test, the specimens were tested at three different stress rates in the range from 6 MPa s-1 to 60 MPa s-1. In order to determine the influence of the specimen's shape on the results of the tensile test, different shapes of specimens were tensed at the same stress rate of 30 MPa s-1. We established that the stress rate and specimen shape affect the tensile test results, but the influence is minimal. Furthermore, difference between the results obtained with various tensile test machines was minimal, but only when tensile test machines with controlled parameters of tensile testing were used.

• Keywords: tensile test, stress rate, specimen shapes, tensile test machine, VCNMO200 steel, PK323MO steel