Mechanics of Deformable Solids
DOI: http://www.dx.doi.org/10.24866/2227-6858/2020-3-3

Molokov K., Maslov K.

KONSTANTIN MOLOKOV, Candidate of Engineering Sciences, Associate Professor,
SPIN: 4021-7431, ScopusID: 57197836777, e-mail: spektrum011277@gmail.com
KIRILL MASLOV, Student, e-mail: kiriklewar@mail.ru
Politechnical Institute
Far Eastern Federal University
Vladivostok, Russia

Calculation methods
for assessing the toughness of welded elements with cracks

Abstract: For welded structures under operation in the Far North, attention must be paid to the performance of welded joints at low temperatures.
The properties of metal of welded joints are changed in the process of treatment, its toughness decreases, and a heterogeneous structure with a large range of different grain sizes is formed. In order to evaluate and be able to correctly control the thermal effect and the consequences of the welding process, it is necessary to solve the problem of analytical determination of impact strength for all zones of the welded joint.
The paper presents an engineering method for evaluation of the impact strength applicable to any area of the welded joint in which there is a sharp or super sharp stress concentrator – a crack. The developed analytical method for calculating the impact strength reflects a qualitative and quantitative codependency of structural and mechanical characteristics and the process of crack development in the temperature range of 77–300 K. The proposed schematization of dependence of the critical coefficient of stress intensity on the temperature made it possible to find coefficients characterizing the properties of the material and to perform calculations of changes in yield strength and tensile strength on operating temperature.
Graphs of the crack development process dependency on the operating temperature for 15ГС and 17ГС steels were constructed, and their comparison with experimental data displays satisfactory agreement. It was found that at endurance limit stresses, the ratio of the crack development process to the critical crack length is constant, non-dependent on temperature, and is equal to 10 for 15ГС and 17ГС steels.
Keywords: impact strength, fracture work, stress intensity factor, crack, ferrite-pearlite steel, heat affected zone, steel tempering.

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