Hardening of a quick-speed steel tool through nitration process with nitrogen controlled potential

The study of the gas nitriding method, which allows obtaining high-quality diffuse layers in high-speed steel P6M5 on the basis of an internal nitrogen hardening zone with no brittle nitride zone, has been viewed. Research results of phase composition of nitrided steel with a change in the nitrogen potential of the atmosphere during dilution of ammonia are presented. Nitrided tool increased resistance during drilling constructional steel and titanium alloy, which is due to precipitation hardening treatment of the internal nitrogenization zone using tungsten nitrides, is given.

Analytical Model of Nonlinear Semi-rigid Frames Using Finite Element Method

Performance-based design for a constructional steel frame in nonlinear-plastic region requires an improvement in order to achieve a reliable structural analysis. The need to explicitly consider the nonlinear behaviour of structures makes the numerical modelling approach much more favourable than expensive and potentially dangerous experimental work. The parameters considered in the analysis are not limited to the linear change of geometry and material yielding, but also include the effect of large deformations, geometrical imperfections, load eccentricities, residual stresses, strain-unloading, and the nonlinear boundary conditions. Such analysis requires the use of accurate mathematical modelling and effective numerical procedures for solving equations of equilibrium. With that in mind, this paper presents the mathematical formulations and finite element procedures of nonlinear inelastic steel frame analysis with quasi-static semi-rigid connections. It is an approach that enables the structural behaviour of constructional steel frames to be traced throughout the entire range of loading until failure. It also provides information on the derivation of the structural analysis by using finite element method. Verification of the developed analytical procedures is conducted with theoretical pin-ended perfect and imperfect columns. A good agreement is achieved between theoretical and developed analytical models. Furthermore, validation of the analytical model with load and unloading behaviour of the material properties for a semi-rigid steel frame was also conducted

Search for the Evaluation of ‘strength-plasticity’ Relation in Constructional Steel

The work considers the approach determining suboptimal relation of strength and plasticity by the example of low-carbon constructional steel 3 (0.14...0.22 % С), which is widely used in metal structures. As parameters for the research, the elements of chemical composition and properties of ferrite-pearlite structure of steel were taken. For the reliability of the obtained results for the evaluation of structure, its quantitative analysis was carried out either by traditional methods or by fractal approach. Combining operating regions of the values of steel properties depending on the chemical composition and area and fractal dimension of pearlite, we got the diagram of the region of compromise for indices of strength limit σВ, σ0,2 and specific elongation δ. Areas with suboptimal relations σВ/δ and σ0.2/δ were defined in the region of compromise for quality criteria. The application of the given approach allows (while adhering to steel production process) to predict areas with stable suboptimal relations for strength and plasticity indices by selecting value range for the elements of chemical composition and analysis of structure.

Model-based analysis of constructional steel structures exemplified by dimensional checking on railway car shells using 3D scanning

The analysis of constructional steel structures (such as car shells for rail vehicles) in terms of dimensional checking according to DIN 25043-2:2012 (presented here) and completeness checking (investigated in Jurdeczka, 2017) represents a challenge because of the dimensions of the test object (20m×3m×3m) and because of the number of mounted parts (several hundred). As presented here and in former publications, the use of 3D scanners allows us to obtain sufficiently comprehensive information about the actual configuration (dimensions and completeness) of the constructional steel structure to be checked. By using an adapted algorithm, the respective 3D model as the target state is superimposed with difference images. These difference images show possible dimensional deviations as well as possible missing parts or, at the least, suspect points. For dimensional checking, there are advantages in the inspection process. In addition, a detailed image can be obtained, which can be used for later evaluations.