On the Critical Resolved Shear Stress and its Importance in the Fatigue Performance of Steels and other Metals with Different Crystallographic Structures

This study deals with the numerical estimation of the fatigue life represented in the form of strength-life (S-N, or Wöhler) curves of metals with different crystallographic structures, namely body-centered cubic (BCC) and face-centered cubic (FCC). Their life curves are determined by analyzing the initiation of a short crack under the influence of microstructure and subsequent growth of the long crack, respectively. Micro-models containing microstructures of the materials are set up by using the finite element method (FEM) and are applied in combination with the Tanaka-Mura (TM) equation in order to estimate the number of cycles required for the crack initiation. The long crack growth analysis is conducted using the Paris law. The study shows that the crystallographic structure is not the predominant factor that determines the shape and position of the fatigue life curve in the S-N diagram, but it is rather the material parameter known as the critical resolved shear stress (CRSS). Even though it is an FCC material, the investigated austenitic stainless steel AISI 304 shows an untypically high fatigue limit (208 MPa), which is higher than the fatigue limit of the BCC vanadium-based micro-alloyed forging steel AISI 1141 (152 MPa).

Characterization of Titanium-Based Films Deposited by DC Sputtering Reactive on AISI 1018 Steel

The coated surfaces first layer Ti and second layer TiO2 as coating Nanostructured thin films of using DC sputtering on structural steel (AISI l018) and study characterization of coating SEM/EDS inspection shown a clearly perfect incorporation of layer by dc sputtering a granular structure of the layer with a variable hemisphere’s forms varied from 33 to 46 nm in size. X-XRD test complete for specimen indicates was found anatase phase titanium dioxide, the resulted coating layer of the target of Ti powders gives different morphology from the Ti layer alone The Specimens roughness average of coated Ti and TiO2with respectively was 4.831nm, 7.93 nm. Found that titanium layer will show a major part in increasing the bonding with improving the bond between the substrate steel AISI (1018) and the titanium oxide layer. The Vickers hardness increases when the coating with a layer of titanium with an oxygen content of ceramic layer is formed from 192.3 HV to 227 for Ti as well as important increase was detected in the Tio2 coating to 240 HV. In addition, Ti and Tio2 thin layer considered as a good barrier for hydrogen permeation through steel structure especially at cathode protection in pipelines.

Finite Element Analysis of Camshaft Using Inventor Software

In this work the 3D model of the camshaft was done using Autodesk Inventor version 2021 with the literature data and finite element analysis is performed by applying restrictions and loads conditions, first by the absence of the torque and then by applying the torque. Three materials were analyzed in both situations: Cast Iron, Stainless Steel AISI 202 and Steel Alloy. Following the comparative study for the three materials, it can be specified the importance of the material for the construction of the camshaft. Keywords: Camshaft, Static analysis, Autodesk Inventor

Study for Performance Increase of a Extractor Device by Steel Replacement of AISI 304 Steel for AISI 420 Steel

The performance of an extractor device used in the food industry was studied from the development of structural analysis through computational modeling based on finite elements. These analyses considered the mechanical properties of AISI 304 and 420 stainless steels, in addition to the tribological aspects of the device in operation. Initially, uniaxial tensile tests were carried out according to the ABNT NBR 6892 standard and hardness tests were carried out according to ASTM E384, E92, and E18 standards. From the mechanical tests, structural analyses were carried out numerically on each of the components of the extractor device. After analyzing all the components, the device was assembled to be tested in operation. The wear and service life of devices made from these two materials were evaluated. From this study, it could be concluded that the extractor device made with AISI 420 stainless steel, in addition to having a lower manufacturing cost, suffered less wear and had an increase in service life of up to 650% compared to the extractor device made with steel stainless steel AISI 304.

Formability Prediction of Laser-Welded Stainless Steel AISI 304 and AISI 430

The effect of laser welding on the mechanical properties and the prediction of formability for austenitic stainless steel AISI 304 and ferritic steel AISI 430 when welded by a YLS-5000 fiber laser, were studied in the paper. The microstructure of the welded joint was analyzed using light microscopy. The mechanical properties were determined by static tensile testing. The forming limit diagrams were produced from notched samples at R5, R17, and R25 mm. The hardness values of the welded joint and the base material were determined using the Vickers method. Samples made of AISI 430 showed that the formability suffered due to laser welding. Longitudinal coarse ferrite grains were observed in the microstructure of the AISI 430 weld metal. The coarse-grained structure of the welded joint and the continuous interface along the centerline caused the failure of the AISI 430 laser-welded samples at significantly lower actual stress and strain values than were required to break the base material. No significant changes in the formability were observed in the AISI 304 samples after laser welding. The growth of dendrites was observed in the microstructure of the AISI 304 welded joint in a direction towards the centerline of the welded joint. A comparison of the experimentally determined FLD0 values and the values calculated from predictive equations showed that a better agreement was achieved for uniform elongation than for the strain hardening exponent. The manufacturability and economic efficiency of selected parts of an exhaust system by hydromechanical drawing were evaluated on the basis of the process capability index Cpk.

Combined Corrosion Inhibitors and Mechanical Properties of Concrete Embedded Steel (AISI 316L) during Accelerated Saline Corrosion Test

The objective of this effort is to study the effect that the combination of fly ash (FA) with a liquid corrosion inhibitor has on the mechanical degradation of 316L rebars embedded in concrete specimens during salt fog testing for a period of four months, as well as the porosity of concrete. Partial replacement of Ordinary Portland Cement (OPC) by FA (0–25%) did not significantly affect the tensile properties of 316L except a small decrease in the elastic modulus and % elongation with FA increasing. Both FA and FA-liquid inhibitor combination resulted in significant reductions in the porosity of the reinforced concrete after 4 m of salt fog testing.

Estimation of the domestic materials application possibility in the active part of a high-speed electric generator for micro-GTP

The article discusses the possibility of using domestic materials in a high-speed electric generator. The features of Japanese electrical steel 20NTN1500 and domestic-made electrical steel grades 2420 and 2421 for the stator magnetic circuit are shown. The features of American steel AISI 455 and structural steel grades Steel 40, Steel 40H, Steel 45 are considered in the case of a rotor. A feature of the use of structural steels in the design of the high-speed electric generator rotor for micro-gas turbine plants is the need for precise observance of the rotor heat treatment mode after its manufacture, control of the dimensions and quality of surface treatment.