Grain Size Effect on Fracture Behavior of the Axis-Tensile Test of Inconel 718 Sheet

2016 ◽  
Vol 35 (10) ◽  
pp. 989-998 ◽  
Author(s):  
B.B. Liu ◽  
J.Q Han ◽  
R. Zhao ◽  
W. Liu ◽  
M. Wan
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Inconel 718 ◽  
Fracture Morphology ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Specimen Thickness ◽  
Forming Process ◽  
Fracture Behaviors ◽  
Micro Parts

AbstractChange in mechanical parts from macro-size to micro-size has become a trend in the metal- and alloy-forming process, with an increasing demand on micro-parts in the last decades. The material mechanical behaviors of micro-size parts are quite different from the conventional ones of macro-size parts due to size effect. It is necessary to further investigate the effects of grain size on material mechanisms in micro-scales, especially fracture behaviors. The fracture behaviors of Inconel 718 sheet with the thickness of 300 μm are studied by uniaxial tensile tests in different grain sizes ranging from 18 to 130 μm. The results show that fracture stress and strain decrease with the increase of grain size. A critical value in the specimen thickness (t) to grain size (d) ratio divides the strength levels into separate stages on the basis of an increase of the inverse of grain size. In addition, the grain size-dependent fracture morphology is changed in the number of dimples and micro-voids decreasing on the fracture surfaces and the sizes of micro-voids changing larger with the increase of grain size.

scholarly journals Numerical investigation on the forming behaviour of stainless/carbon steel bimetal composite

2018 ◽  
Vol 185 ◽  
pp. 00012
Author(s):  
Zhou Li ◽  
Jingwei Zhao ◽  
Qingfeng Zhang ◽  
Sihai Jiao ◽  
Zhengyi Jiang
Keyword(s):  
Carbon Steel ◽  
Circumferential Stress ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Composite Sheet ◽  
Forming Process ◽  
Thickness Strain ◽  
Forming Simulation ◽  
Bimetal Composite ◽  
Forming Behaviour

Bimetal composites have wide applications due to their excellent overall performance and relatively low comprehensive cost. The aim of this study is to investigate the forming behaviour of stainless/carbon steel bimetal composite during stamping by finite element method (FEM). In this work, the bonding interface of bimetal composite sheet was assumed to be perfect without delamination during the plastic forming process for simplicity. Uniaxial tensile tests on base metal (carbon steel) and compositing metal (stainless steel) were first carried out, respectively, in order to obtain the tensile properties of each of the component materials required in the forming simulation. Processing variables, including the layer stacking sequence, relative thickness ratios of two layers and friction were considered, and their effects on the distributions of circumferential stress and thickness strain were analysed. The bimetal composite sheet was set as the eight-node solid elements in the developed FEM model, which is effective for evaluating the distributions of circumferential stress and thickness strain, and predicting the high-risk region of necking during the stamping of bimetal composites. The simulation results can be used as an evaluation indicator of the capability of forming machine to ensure the bimetal composite can be safely formed.

Effect of Fast Annealing on Microstructure and Mechanical Properties of Non-Oriented Al-Si Low C Electrical Steels

2007 ◽  
Vol 560 ◽  
pp. 29-34 ◽  
Author(s):  
Emmanuel Gutiérrez C. ◽  
Armando Salinas-Rodríguez ◽  
Enrique Nava-Vázquez
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
Tensile Tests ◽  
Rate Of Change ◽  
Uniaxial Tensile ◽  
Electrical Steels ◽  
Offset Yield Strength ◽  
Microstructure And Mechanical Properties ◽  
Increasing Temperature

The effects of heating rate and annealing temperature on the microstructure and mechanical properties of cold rolled Al-Si, low C non-oriented electrical steels are investigated using SEM metallography and uniaxial tensile tests. The experimental results show that short term annealing at temperatures up to 850 °C result in microstructures consisting of recrystallized ferrite grains with sizes similar to those observed in industrial semi-processed strips subjected to long term batch annealing treatments. Within the temperature range investigated, the grain size increases and the 0.2% offset yield strength decreases with increasing temperature. It was observed that the rate of change of grain size with increasing temperature increases when annealing is performed at temperatures greater than Ac1 (~870 °C). This effect is attributed to Fe3C dissolution and rapid C segregation to austenite for annealing temperatures within the ferrite+austenite phase field. This leads to faster ferrite growth and formation of pearlite when the steel is finally cooled to room temperature. The presence of pearlite at room temperature decreases the ductility of samples annealed at T > Ac1.

Superplasticity and Microstructure Evolution of Electrodeposited Nanocrystalline Nickel

2007 ◽  
Vol 551-552 ◽  
pp. 539-544 ◽  
Author(s):  
S. Ding ◽  
Kai Feng Zhang ◽  
Guo Feng Wang
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Room Temperature ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Intergranular Cracking ◽  
Mean Grain Size ◽  
Electrodeposited Nickel ◽  
Superplastic Properties

Nanocrystalline pure nickel (nc-Ni) was produced by pulse electrodeposition and its superplastic properties at and above room temperature were investigated. The electrodeposited nickel has a narrow grain size distribution with a mean grain size of 70nm. Uniaxial tensile tests at room temperature showed that nc-Ni has a limited plasticity but high tensile strength up to 1GPa at strain rates between 10-5 and 10-2s-1. However, when the temperature increased to 420 and higher, test specimens showed uniform deformation and the elongation value was larger than 200%. A maximum elongation value of 380% was observed at 450°C and a strain rate of 1.67x10-3s-1, SEM and TEM were used to examine the microstructures of the as-deposited and deformed specimens. The results indicated that fracture was caused by intergranular cracking and most cracks were originated from the brittle oxide formed during the tensile test. Grain coarsening was observed in the deformed specimen. The role of temperature and strain on grain growth was evaluated by comparing the microstructure of deformed samples with that of samples statically annealed. Deformation mechanism was discussed based upon the deformed microstructure and strain rate jump tests.

scholarly journals Performance of Thermo-Mechanically Processed AA7075 Alloy at Elevated Temperatures—From Microstructure to Mechanical Properties

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 884 ◽  
Author(s):  
Seyed Vahid Sajadifar ◽  
Emad Scharifi ◽  
Ursula Weidig ◽  
Kurt Steinhoff ◽  
Thomas Niendorf
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Softening Mechanism ◽  
Rate Dependent ◽  
Heat Treated ◽  
Different Temperatures ◽  
Die Forming

This study focuses on the high temperature characteristics of thermo-mechanically processed AA7075 alloy. An integrated die forming process that combines solution heat treatment and hot forming at different temperatures was employed to process the AA7075 alloy. Low die temperature resulted in the fabrication of parts with higher strength, similar to that of T6 condition, while forming this alloy in the hot die led to the fabrication of more ductile parts. Isothermal uniaxial tensile tests in the temperature range of 200–400 °C and at strain rates ranging from 0.001–0.1 s−1 were performed on the as-received material, and on both the solution heat-treated and the thermo-mechanically processed parts to explore the impacts of deformation parameters on the mechanical behavior at elevated temperatures. Flow stress levels of AA7075 alloy in all processing states were shown to be strongly temperature- and strain-rate dependent. Results imply that thermo-mechanical parameters are very influential on the mechanical properties of the AA7075 alloy formed at elevated temperatures. Microstructural studies were conducted by utilizing optical microscopy and a scanning electron microscope to reveal the dominant softening mechanism and the level of grain growth at elevated temperatures.

scholarly journals Determination of the Plastic Strain by Spherical Indentation of Uniaxially Deformed Sheet Metals

2015 ◽  
Vol 651-653 ◽  
pp. 950-956 ◽  
Author(s):  
Mohamad Idriss ◽  
Olivier Bartier ◽  
Gérard Mauvoisin ◽  
Charbel Moussa ◽  
Eddie Gazo Hanna ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Accurate Determination ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Spherical Indentation ◽  
Instrumented Indentation ◽  
Forming Process ◽  
Hardening Law ◽  
Indentation Tests

This work consists of determining the plastic strain value undergone by a material during a forming process using the instrumented indentation technique (IIT). A deep drawing steel DC01 is characterized using tensile, shear and indentation tests. The plastic strain value undergone by this steel during uniaxial tensile tests is determined by indentation. The results show that, the identification from IIT doesn’t lead to an accurate value of the plastic strain if the assumption that the hardening law follows Hollomon law is used. By using a F.E. method, it is shown that using a Voce hardening law improves significantly the identification of the hardening law of a pre-deformed material. Using this type of hardening law coupled to a methodology based on the IIT leads to an accurate determination of the hardening law of a pre-deformed material. Consequently, this will allow determining the plastic strain value and the springback elastic strain value of a material after a mechanical forming operation.

Progressive and Compound Forming for Producing Plunger-Typed Microparts by Using Sheet Metal

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Jun-Yuan Zheng ◽  
Ming-Wang Fu
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Sheet Metal ◽  
Mass Production ◽  
Grain Size Effect ◽  
Sheet Metals ◽  
Forming Process ◽  
Deformation Behaviors ◽  
Progressive Forming ◽  
Insight Into

Abstract The plunger part in temporary electronic connectors is traditionally fabricated by micromachining. Progressive forming of microparts by directly using sheet metals is developed and proven to be an efficient microforming process to overcome some intrinsic drawback in realization of mass production of microparts. By employing this unique micromanufacturing process, an efficient approach with progressive microforming is developed to fabricate plunger-shaped microparts. In this endeavor, a progressive forming system for making microplungers using extrusion and blanking operations is developed, and the grain size effect affected deformation behaviors and of surface qualities of the microformed parts are studied. The knowledge for fabrication of plunger-shaped microparts via progressive microforming is developed, and the in-depth understanding and insight into the deformation behaviors and tailoring the product quality and properties will facilitate the design and development of the forming process by using this unique microforming approach.

Predicting Edge Cracks on Shear-Cut High-Strength Steels by Modified Uniaxial Tensile Tests

2016 ◽  
Vol 703 ◽  
pp. 49-55 ◽  
Author(s):  
Martin Feistle ◽  
Isabella Pätzold ◽  
Roland Golle ◽  
Wolfram Volk
Keyword(s):  
Tensile Test ◽  
Measurement Method ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Contact Measurement ◽  
Edge Cracks ◽  
Near Future

During the forming of high-strength steels, edge cracks occur unexpectedly on sheared edges e.g. during collar forming. A non-contact measurement method based on the well-known tensile test was developed. It allows the investigation of the formation of edge cracks under tensile loads and determining general criteria to predict the formation of edge cracks during a specific forming process. The criteria are validated experimentally by means of the collar-forming test. In conjunction with the proposed line-fit-method these criteria can be implemented easily in FEM software in the near future for the prediction of edge cracks.

Microstructural Behaviour in Rotary Forging of Inconel 718

2012 ◽  
Vol 504-506 ◽  
pp. 169-174 ◽  
Author(s):  
Ángela Mangas ◽  
Maite Santos ◽  
Juan San José ◽  
Garbiñe Atxaga ◽  
Olatz Adarraga
Keyword(s):  
Grain Size ◽  
Inconel 718 ◽  
Forming Process ◽  
Numerical Work ◽  
Forging Process ◽  
Rotary Forging ◽  
Recrystallization Mechanism ◽  
Microstructural Behavior

In the work developed in this paper, the model of the microstructural behavior of Inconel 718 for the rotary forging process is studied. This process is presented as an alternative to the conventional forging. The window process of Inconel 718 is very narrow, so the requirements for manufacturing Inconel are very restrictive. Optimization of the rotary forging process was carried out in order to manufacture Inconel pieces with good microstructural distribution. Microstructural specification was given by aeronautic sector. Numerical work was done in order to simulate the microstructural behavior during the forming process. This method was used: a) to understand the recrystallization mechanism that take place in rotary forging processes, b) to compare the microstructure between a piece done in conventional forging and another done in rotary forging and c) to study the influence of the initial grain size in the final piece.

Sensitivity Analysis to Optimise the Microstructural Properties of an Inconel 718 Component Manufactured by Rotary Forging

2013 ◽  
Vol 554-557 ◽  
pp. 234-247 ◽  
Author(s):  
Ángela Mangas ◽  
Maite Santos ◽  
Jose Ignacio Zarazua ◽  
Juan San José ◽  
Garbiñe Atxaga ◽  
...  
Keyword(s):  
Grain Size ◽  
Inconel 718 ◽  
Experimental Tests ◽  
Forming Process ◽  
Homogeneous Microstructure ◽  
Isolation System ◽  
Isolation Technique ◽  
Rotary Forging ◽  
Final Microstructure ◽  
Transfer Operation

Microstructural behaviour of Inconel 718 using rotary forging as forming process is presented in this paper. This work is the continuation of a previous one, presented in ESAFORM 2012, in which the numerical model was described and previous results about microstructural behaviour were shown. Several simulations are carried out in order to investigate the effect of initial grain size, temperature and strain rate in microstructure. Experimental tests are done in order to validate the numerical results, analyzing the final microstructure. Preparation of the experimental equipment is shown: heating tool system, thermal isolation technique, tool design for the integration of the heating and the isolation system. Heat loss during the transfer operation between furnace and rotary forging machine is measured experimentally, in order to obtain a precise initial temperature value of the part at the beginning of the process. The experimental tests allow validating the simulation work, obtaining the real input parameters for the numerical calculation. Two ways of forming are obtained depending on the initial grain size. The optimal combination of the rotary forging process parameters listed above is determined in achieving a fine and homogeneous microstructure.

Application of Dic Technique for Monitoring of Deformation Process of Spr Hybrid Joints / Zastosowanie Techniki Dic Do Obserwacji Procesu Deformacji Hybrydowych Połaczen Typu Spr

2013 ◽  
Vol 58 (1) ◽  
pp. 119-125 ◽  
Author(s):  
T. Sadowski ◽  
M. Knec
Keyword(s):  
Deformation Process ◽  
Load Capacity ◽  
Tensile Tests ◽  
Lap Joints ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Specimen Preparation ◽  
Forming Process ◽  
Absorption Increase ◽  
Dic Technique

Digital Image Correlation (DIC) technique gives possibility to observe deformation process in many applications including self-piercing riveting (SPR) hybrid joint. The hybrid SPR joint consists of simple SPR joint made of two adherends, steel tubular rivet (total length of 5 mm) and an adhesive. The adhesive was applied before piercing process. For specimen preparation two different aluminum alloys were used: 2024 and 5005 (2mm thickness both) with tensile strength 400 and 160MPa, respectively. For better understanding of joint forming process and to allow DIC strains observation during the joint creation, a special holder was designed with precisely polished die. The tests were performed by application of the 100kN servo-hydraulic machine, which recorded time, load, displacement and was synchronized with the DIC system. The joint forming process was carried out with 2 mm/min constant speed. During piercing process rivet and upper surface of the adherend were observed and the major strain states were estimated. The uniaxial tensile tests of single lap joints (SLJ) up to the final failure were performed and the displacements and the strains were recorded. In particular the rivet deformation was observed also during the whole loading process. The hybrid SPR joints are very effective, because the load capacity and energy absorption increase more than 1.5 times in comparison to the simple SPR joints.

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