Goran Vukelić

Tool Material Behavior at Elevated Temperatures

In this article experimentally obtained data related to material mechanical properties, material behavior at elevated temperatures and numerical modeling of material creep responses are presented. Tensile tests at different elevated temperatures are carried out, and for some of these temperatures one-dimensional short time creep tests for different constant stresses are made. Before presented experimental investigations the used materials were not treated. The curves representing specimen strain elongation are also presented. The materials under consideration are 56NiCrMoV7 (1.2714) and X153CrMoV12 (1.2379).

Numerical prediction of fracture behavior for austenitic and martensitic stainless steels

Two types of stainless steels are compared in this paper, austenitic X15CrNiSi25-20 and martensitic X20Cr13, based on their numerically predicted fracture behavior. There are engineering applications where both of the steels can be considered for use and where these materials can be exposed to crack occurrence and growth, so proper distinction between them is desirable. Comparison is made on the basis of J-integral values that are numerically determined using finite element (FE) stress analysis results. FE analysis is performed on compact tensile (CT) and single-edge notched bend (SENB) type specimens that are usually used in standardized J-integral experimental procedures. Calculated J-integral values are plotted versus crack growth lengths for mentioned specimens. Results show somewhat higher values of J-integral for steel X20Cr13 than X15CrNiSi25-20. Further, when comparing J-integral values obtained through FE model of CT and SENB specimen, it is noticed that CT specimens give somewhat conservative results. Results obtained by this analysis can be used in predicting fracture toughness assessment during design process.

Prediction of Fracture Behavior of 20MnCr5 and S275JR Steel Based on Numerical Crack Driving Force Assessment

AbstractTwo types of steel, 20MnCr5 and S275JR, are compared in this paper based on numerical prediction of their fracture behavior. The comparison was made using the numerically determined J-integral, an important fracture mechanics parameter. For that reason, a numerical algorithm that calculates the J-integral as a measure of crack driving force was developed. As an input, the algorithm uses results from the finite element analysis conducted on numerical models of two types of specimens usually used in experimental fracture investigations, single-edge notched bend (SENB) and disc compact type (DCT). The J-integral results obtained are plotted versus specimen crack growth size (Δa) for a range of specimens’ initial crack sizes (a/W=0.25, 0.5, 0.75).

Comparison of Material Properties and Creep Behavior of 20MnCr5 and S275JR Steels

t is well known that the optimization procedure has an important role in the structure design. Furthermore, experimentally obtained data of material behavior is known to serve as the most relevant data in the mentioned design procedure. Therefore, this paper sets out to examine some experimentally determined data of the material subjected to certain environmental conditions. Based on these parameters, some analyses of material behavior can be made. In addition, data are of such nature that it is possible to make an appropriate comparison between the two investigated materials. Materials under considerations were 20MnCr5 steel and S275JR steel. Both of materials have been subjected to the same environmental conditions and the following properties can be singled out: ultimate tensile strength, 0.2 offset yield strength, the modulus of elasticity, elongation, creep behavior and Charpy impact energy. Each of the mentioned details are determined by the corresponding test, e.g. data related to strengths and to creep behavior are determined by tensile tests while impact energy is determined by Charpy impact test. In this way, the obtained values are presented in the form of the engineering stress-strain diagrams, creep curves and impact energy data.

Uniaxial Properties versus Temperature, Creep and Impact Energy of an Austenitic Steel

Abstract In this paper, uniaxial material properties, creep resistance and impact energy of the austenitic heat-resistant steel (1.4841) are experimentally determined and analysed. Engineering stress–strain diagrams and uniaxial short-time creep curves are examined with computer-controlled testing machine. Impact energy has been determined and fracture toughness assessed. Investigated data are shown in the form of curves related to ultimate tensile strength, yield strength, modulus of elasticity and creep resistance. All of these experimentally obtained results are analysed and may be used in the design process of the structure where considered material is intended to be applied. Based on these results, considered material may be classified as material of high tensile strength (688 MPa/293 K; 326 MPa/923 K) and high yield strength (498 MPa/293 K; 283 MPa/923 K) as well as satisfactory creep resistance (temperature/stress →

Analysis of Austenitic Stainless Steels (AISI 303 and AISI 316Ti) Regarding Crack Driving Forces and Creep Responses

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Comparison of Some Structural and Stainless Steels Based on the Mechanical Properties and Resistance to Creep

strain (%) at 1,200 min: 823 K/167 MPa →

Analysis of the Dependence of Material Properties on Temperature – Steel 1.4122

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Comparison of material properties: Steel 20MnCr5 and similar steels

0.25 %; 923 K/85 MPa →

FE modelling of multi-walled carbon nanotubes

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