Browsing by Subject "stainless steel"

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Access status: Open Access ,
Characterization of microstructure and mechanical properties of laser-welded stainless steels
(Wydawnictwa AGH, 2016) Koclęga, Damian; Radziszewska, Agnieszka; Kąc, Sławomir; Zowczak, Włodzimierz; Dębowska, Aleksandra; Jędrusik, Mateusz; Petrzak, Paweł
This work presents the laser welding of dissimilar X12CrCoWVNbN12-2-2 and X10CrNi18-10 steels. This system is of interest, as laser welding offers new flexibility in the joining of metals and laser welds (LWs) and are usually of high quality, they are obtained only after the optimization of process parameters. The aim of the work was to investigate the microstructure, chemical composition, and hardness changes of laser-welded steels. After laser welding, two zones were generated in the processed materials: a fusion zone and a heat-affected zone. Due to solidification, a refinement of the microstructure occurred in the fusion zone. Examinations of the chemical composition of particular melted areas showed the occurrence of Nb-rich precipitations. The laser welding of steels led to increased hardness in the fusion zone (about 240–530 HV0.3).
Access status: Open Access ,
Manufacturing methods of alloy layers on casting surfaces
(2017) Szajnar, Jan; Wróbel, Tomasz; Dulska, Agnieszka
In this paper, we presented the technology of layered castings based on the founding method of layer coating directly in the cast process known as the method of mold cavity preparation by monolithic or granular material of insert. Prepared castings consist of two fundamental parts: the base part and working part (layer). The base part of a layered casting is usually typical foundry material (i.e., pearlitic grey cast iron with flake graphite or ferritic-pearlitic carbon cast steel), whereas the dependence of an insert type (i.e., monolithic or granular) working part (layer) is suitably plated with ferritic and austenitic alloy steels or a layer from a Cr-base alloy. The ratio of thickness between the base and working part is between 8:1 and 10:1. The quality of the layered castings was evaluated on the basis of ultrasonic non-destructive testing, structure, and selected usable property research. According to work out technology, the prepared layered castings can work in conditions that require high heat resistance and/or corrosion resistance from the working surface layer of an element in a medium of industrial water, for example. Moreover, in the case of applying an insert based on Cr-base alloy powder on the working surface layer, it is possible to obtain high hardness and abrasive wear resistance.
Access status: Open Access ,
Polycrystalline plasticity analysis of cyclic loading and stress relaxation in 316H austenitic stainless steel
(Wydawnictwa AGH, 2025) Acar, Sadik Sefa; Yalçinkaya, Tuncay
The mechanical behavior of 316H austenitic stainless steel is investigated in this study under cyclic strain-controlled loading with and without hold periods at elevated temperatures. Understanding the low-cycle fatigue (LCF) and fatigue-creep interaction (FCI) characteristics is essential for ensuring the structural performance and safety of reactor components, particularly under conditions typical of modular and generation IV reactors. The new generation of nuclear power plants require more resistant and durable materials as the operating environments impose significantly higher demands, including increased neutron irradiation levels and elevated operating temperatures, leading to accelerated material degradation. A combined isotropic-kinematic hardening model within a crystal plasticity framework is employed to capture the cyclic and time-dependent mechanical response of the material. Model parameters are calibrated by fitting cyclic loading simulation results to experimental data at 550°C using polycrystalline representative volume elements (RVE). Strain-controlled uniaxial loading simulations are performed to analyze peak stress evolution throughout cyclic loading and stress relaxation behavior during strain-hold periods. The RVE simulation results are in strong agreement with experiments under LCF loading. For the loading with strain-holds, stress relaxation during hold periods exhibits two distinct stages: an initial rapid decay followed by a steady decline, both of which are captured in simulations. Beyond the macroscopic response, analyses reveal the heterogeneous evolution of field variables at the microstructural level, as strain hardening during loading and stress relaxation during hold periods varied across grains due to their crystal orientations and interactions with neighboring grains. These findings enhance the understanding of high-temperature mechanical behavior at both macroscopic and microstructural scales, contributing to the efforts for the design, operation, and life extension of nuclear reactor components.