scholarly journals Steel nitriding optimization through multi-objective and FEM analysis

2015 ◽  
Vol 3 (1) ◽  
pp. 71-90 ◽  
Author(s):  
Pasquale Cavaliere ◽  
Angelo Perrone ◽  
Alessio Silvello
Keyword(s):  
Potential Temperature ◽  
Fem Analysis ◽  
Fatigue Properties ◽  
Processing Conditions ◽  
Steel Composition ◽  
Multi Objective ◽  
Microstructural Behavior ◽  
Nitrogen Potential ◽  
Control Designs ◽  
Temperature Time

Abstract Steel nitriding is a thermo-chemical process leading to surface hardening and improvement in fatigue properties. The process is strongly influenced by many different variables such as steel composition, nitrogen potential, temperature, time, and quenching media. In the present study, the influence of such parameters affecting physic-chemical and mechanical properties of nitride steels was evaluated. The aim was to streamline the process by numerical–experimental analysis allowing defining the optimal conditions for the success of the process. Input parameters–output results correlations were calculated through the employment of a multi-objective optimization software, modeFRONTIER (Esteco). The mechanical and microstructural results belonging to the nitriding process, performed with different processing conditions for various steels, are presented. The data were employed to obtain the analytical equations describing nitriding behavior as a function of nitriding parameters and steel composition. The obtained model was validated, through control designs, and optimized by taking into account physical and processing conditions. Highlights The paper shows the development of a model based on very broad experimental activity. The data were employed to provide a provisional tool for nitrided steel mechanical and microstructural behavior. A very good experimental–numerical correlation was found.

scholarly journals Evaluation of Fatigue Characteristics of Aluminum Alloys and Mechanical Components Using Extreme Value Statistics and C-specimens

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1915
Author(s):  
Jungsub Lee ◽  
Sang-Youn Park ◽  
Byoung-Ho Choi
Keyword(s):  
Aluminum Alloys ◽  
Fem Analysis ◽  
Extreme Value ◽  
Fatigue Tests ◽  
Extreme Value Statistics ◽  
Fatigue Properties ◽  
Chemical Compositions ◽  
Cross Sectional ◽  
Fatigue Characteristics ◽  
Mechanical Components

In this study, the fatigue characteristics of aluminum alloys and mechanical components were investigated. To evaluate the effect of forging, fatigue specimens with the same chemical compositions were prepared from billets and forged mechanical components. To evaluate the cleanliness of the aluminum alloys, the cross-sectional area of specimens was observed, and the maximum inclusion sizes were obtained using extreme value statistics. Rotary bending fatigue tests were performed, and the fracture surfaces of the specimens were analyzed. The results show that the forging process not only elevated the fatigue strength but also reduced the scatter of the fatigue life of aluminum alloys. The fatigue characteristics of C-specimens were obtained to develop finite-element method (FEM) models. With the intrinsic fatigue properties and strain–life approach, the FEM analysis results agreed well with the test results.

Optimizing sulfurisation conditions in the fabrication of Cu2ZnSnS4absorber layers from electroplated precursors

2009 ◽  
Vol 1210 ◽  
Author(s):  
Jonathan James Scragg ◽  
Daniel Wolverson ◽  
Guillaume Zoppi ◽  
Laurence M Peter
Keyword(s):  
Simple Model ◽  
Grain Growth ◽  
Phase Formation ◽  
Bulk Material ◽  
Limiting Factor ◽  
Processing Conditions ◽  
Surface Phases ◽  
Rate Limiting ◽  
Temperature Time ◽  
Photoelectrochemical Measurement

AbstractUsing direct photoelectrochemical measurement of the photocurrent obtained from Cu2ZnSnS4(CZTS) absorber layers made by a two-stage electroplating-sulfurisation process, the influence of processing conditions (temperature, time, and pressure) on material quality was investigated with a view to understanding the long sulfurisation times usually found in the literature. The improvement in photocurrent due to KCN etching was also studied, and seems to be due both to removal of surface phases and also slower etching of the bulk material. The optimum sulfurisation time was found to be around 50 minutes, despite evidence that sulfur incorporation and phase formation are complete within 5 minutes. Slow grain growth was suggested as a rate-limiting factor, and a rate constant was derived based on a simple model.

Low Cycle Fatigue Tests With the Use of Miniaturized Test Specimens

2017 ◽  
Author(s):  
Jan Dzugan ◽  
Radek Prochazka ◽  
Pavel Konopik
Keyword(s):  
Residual Life ◽  
Low Cycle Fatigue ◽  
Fem Analysis ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Treatment Development ◽  
Structured Materials ◽  
Testing Procedures ◽  
Large Application

Determination of mechanical properties with the use of sub-sized specimens is topic a high interest nowadays. The application of the sub-sized samples is quite wide for all cases where only limited amount of the experimental material is available such as evaluation of additively manufactured products properties, residual life of in-service components, properties determination of developed nano-structured materials, assessment of dilatometric samples used for thermal and thermo-mechanical treatment development, local properties of components, weld joints and so on. Concerning this large application field it would be very useful to prepare standard for small size samples especially for the most demanded material properties: tensile properties, notch impact transition temperature, fatigue properties, fracture toughness and creep. Current paper is going to deal with the low fatigue (LCF) properties assessment with the use of miniaturized specimens’. There were proposed specimen geometries with the use of FEM analysis and testing procedures for considered mini-specimens tests were developed. In the case of strain controlled LCF tests, contactless testing system had to be established for testing of small sized specimens, where it is not possible to apply standard mechanical extensometers for test control. Moreover, LCF procedure for high temperature tests was also successfully established here. The LCF results were subsequently used for Manson-Coffin parameters determination. Results of low cycle tests for several steels are confronted with the results of standard sized specimens with very good agreement for all considered conditions.

scholarly journals The Organosolv Fractionation of Cork Components

Holzforschung ◽  
2002 ◽  
Vol 56 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Nereida Cordeiro ◽  
Carlos Pascoal Neto ◽  
Joao Rocha ◽  
Mohamed N. Belgacem ◽  
Alessandro Gandini
Keyword(s):  
Cell Wall ◽  
Solid State ◽  
Solid State Nmr ◽  
Catalyst Concentration ◽  
Quercus Suber ◽  
Extraction Yield ◽  
Processing Conditions ◽  
Process Variables ◽  
Temperature Time ◽  
Water Ratio

Summary Extractive-free cork from Quercus suber L. was submitted to organosolv fractionation and the effects of different process variables, such as ethanol/water ratio, temperature, time and the presence of acidic or alkaline catalysts, were studied. The variation of the relative proportions of extracted components, as a function of the processing conditions, could thus be established. Whereas the addition of 0.1Macetic acid only increased the yield of extracted materials from about 15 to 23 %, the use of sodium hydroxide, at the same concentration, produced a jump to 76 %. In the case of the alkaline organosolv fractionation, an increase in process temperature, time and catalyst concentration led to an increase in the extraction yield, although in some cases this increase did not follow a sustained trend, as in the case of reaction time. Increasing the ethanol/water ratio led to a higher selectivity in favour of suberin extraction. Residual cork from different organosolv processes was characterised by FTIR and 13C solid-state NMR. The latter technique provided some valuable information about both process selectivity and cork morphology, particularly with respect to the positioning of suberin macromolecules in the cell wall.

Effect of Plastic Deformation on Torsional Fatigue Properties of a Low Carbon Steel

2006 ◽  
Vol 324-325 ◽  
pp. 63-68
Author(s):  
Shinichi Nishida ◽  
Nobusuke Hattori ◽  
Cong Ling Zhou ◽  
Akihiro Uchisako
Keyword(s):  
Plastic Deformation ◽  
Carbon Steel ◽  
Surface Hardness ◽  
Low Carbon Steel ◽  
Fem Analysis ◽  
Axial Direction ◽  
Residual Stress Distribution ◽  
Fatigue Properties ◽  
Low Carbon ◽  
Torsional Fatigue

This paper is aimed to investigate the effect of roller working on the torsional fatigue properties of a typical low carbon steel referring by the resutls of FEM analysis. Three types of specimens had been prepared with plastic deformation value of 0, 0.5 and 1.0mm, respectively. The main results obtained in this study are as follows: (1) The torsional fatigue strength of roller-worked specimen with 1.0mm plastic deformation is increased more than twice of that of non-rollerworked specimens. (2) Surface hardness of roller worked specimen is much higher than that of the non-roller worked one, and compressed and elongated structure is formed at the notch bottom of the specimen. (3) Crack length along the axial direction of roller worked specimens is longer than that of the non-roller worked specimen, and plural cracks initiated and propagated in the roller worked specimens. (4) The residual stress distribution at the specimen’s notch bottom was analysed using FEM analysis and it is verified the same tendency as the experimental results.

Characteristics of Repair Welds on Aged 2.25Cr-1Mo Steel for Creep and Creep-Fatigue Applications

2004 ◽  
Author(s):  
Yoshio Takagi ◽  
Shigeru Otsuki ◽  
Takuya Ito ◽  
Isamu Nonaka
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Weak Link ◽  
Fem Analysis ◽  
Fatigue Tests ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Strain Concentration ◽  
Fine Grained ◽  
Creep Fatigue

The creep and the creep-fatigue properties of full repair welds (FRW) and partial repair welds (PRW) were evaluated in this study. Since the PRW contained the service-aged girth weld which was the weak link of the cross weld, the PRW was a shorter creep strength than the FRW. Moreover, the PRW showed a remarkably shorter creep-fatigue life compared to that of the FRW. In order to consider the poor creep-fatigue properties of PRW, finite element (FEM) analysis was conducted with experimentally measured material constants using service-aged base metal, aged weld metal, simulated coarse-grained HAZ, simulated fine-grained HAZ and repair weld metal. The analysis revealed that the strain concentrated on the aged and softened base metal or girth weld metal of the repair-welded cross weld specimen and not on the virgin cross weld specimen. The failure locations in creep-fatigue tests were close to the strain concentrated zone. Thus, the strain concentration is considered to work as a significant role and dominate the creep-fatigue properties of repair welds. In addition, the ductility of the weld metal was much less than that of the base metal. Consequently, the interaction of the strain concentration and the lack of ductility induced the lesser creep-fatigue properties of the PRW.

EFFECTS OF HEAT TREATMENT ON THE NUTRITIVE VALUE OF WHOLE RAPESEED FOR POULTRY

1972 ◽  
Vol 52 (1) ◽  
pp. 189-194 ◽  
Author(s):  
A. WOODLY ◽  
W. K. BILANSKI ◽  
J. D. SUMMERS
Keyword(s):  
Marked Improvement ◽  
Nutritive Value ◽  
Treatment Time ◽  
Control Diet ◽  
Treatment Temperature ◽  
Processing Conditions ◽  
Length Of Treatment ◽  
Wide Range ◽  
Processing Treatment ◽  
Temperature Time

Three experiments were conducted to investigate the nutritive value of full-fat rapeseed when subjected to heating temperatures ranging from 232 to 427 C for periods of from 1 min to 5 sec. Chicks either 1 day or 1 week old were fed diets containing treated rapeseed, and weight gain, feed:gain ratio, and thyroid weights were recorded. Although there was variability in response to the test diets, depending on treatment temperature and length of treatment time, the data indicate a marked improvement in nutritive value of full-fat rapeseed with proper processing conditions. Evidently a relatively wide range of temperature–time combinations could be used to obtain the optimum processing treatment. The study indicated that the test diets were not palatable to chicks at 1 day of age; however, when fed over a 4-week period, the birds overcame the slow start and were as heavy as those fed a control diet in which the protein was supplied by soybean meal.

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