Maximum Formability Research Articles

Exploring the influence of cosegregation on mechanical properties of Mg [formula omitted] twin boundaries: A first-principles investigation

This study employs first-principles calculations to investigate the impact of solute segregation on the mechanical properties of the Mg twin boundary (TB). The investigation delves into single-element segregation and multielement cosegregation at the Mg{101¯1} twin boundary. Several parameters, including segregation energy, solubility energy, and strengthening/embrittlement energy, are determined, and Voronoi volume and electronic structure evolution are analyzed. The study discloses the effects of 21 solute single-segregation, as well as the segregation mechanism of Ca, Y, and Zn solute elements in paired combinations. A comparative assessment of the optimal combination for cosegregation of Ca/Y atoms with larger atomic radii and Zn atoms with smaller atomic radii reveals that the solute elements Ca and Y induce more robust energy changes at the interface segregation than Zn. Additionally, electronic structure analysis suggests that charge transfer between solute atoms with large atomic radii and solute atoms with small atomic radii can strengthen the chemical bond at the twin boundary, thereby enhancing the maximum tensile degree, ductility, and formability of the material. The outcomes of this investigation have significant theoretical implications for composition design and the development of novel high-performance multielement magnesium alloys.

Forming limit diagram and optimization of process parameters in SPIF of Inconel 625 aviation-grade superalloy

PurposeThis paper aims to optimize the single-point incremental forming process variables for realizing higher formability in Inconel 625 components and to plot the forming limit diagram for Inconel 625 aviation-grade superalloy.Design/methodology/approachThe formability of Inconel 625 components has been measured in terms of major strain, minor strain and minimum sheet thickness. Response surface methodology with desirability function analysis has been used to achieve maximum formability. The finite element analysis has been conducted at optimal parametric setting.FindingsThe derived forming limit diagram proves that the maximum forming limit for Inconel 625 is 57.5° at the optimal parametric setting, achieved with desirability of 0.995. The outcomes of finite element analysis conducted at optimal parametric setting show excellent agreement with confirmation experiment results.Practical implicationsInconel 625 superalloy is frequently used in aircraft and other high-performance applications for its superior strength.Originality/valueIt has been suggested that to enhance formability, higher tool rotation speed, minimum step-size, larger tooltip diameter and higher wall angle must be used. Wall angle is the governing parameter among all the parameters.

FEM Simulation of Surface Micro-Groove Structure Fins Produced by Cryogenic-Temperature Extrusion Machining

In the process of metal cutting, a large amount of chips that are difficult to reuse will be produced, resulting in resource waste. As a novel metal forming process, cryogenic-temperature extrusion machining (CT-EM) can directly process chips into usable fins with a surface micro-groove structure, which has the advantage of high efficiency, energy saving and flexibility. In this study, the effects of four parameters (compression ratio λ, rake angle of the tool α, friction coefficient μ and the constraining tool corner radius R) on the effective stress, temperature and formability of micro-groove fins produced by CT-EM and room-temperature extrusion machining (RT-EM) are investigated. The results show that the maximum effective stress and formability of CT-EM are larger than that of RT-EM, which indicates that CT-EM has greater advantages in the preparation of micro-groove fins. At a λ of 0.7, the formability of CT-EM is the best. Reducing the λ and α, or increasing the μ, can improve the forming effect of the fins. CT-EM can produce micro-groove fins with the best formability when λ = 0.7, α = 5°, μ = 0.75 and R = 0.1 mm.

Tool and formability multi-response optimization for ultimate strength and ductility of AA8011 during axial compression

Friction stir incremental forming is a dieless forming process achieved through the severe plastic deformation of sheet metals by localized heat through tool friction with sheet metal. Tool rotation contributes significantly to determining the local heat generation and deformation of the sheets. In this study, a novel attempt was made to improve the desired surface quality with minimum tool wear using three different tool coatings. To identify the optimal parameters, process factors such as spindle speed, step size, and table feed were considered with two response parameters forming force and surface roughness. A total of 27 experiments based on a full factorial design were performed. During this optimization using TOPSIS, parameters are selected based on which FSIF parts should attain the minimum forming force and surface roughness. Based on the results obtained, the titanium nitride coating in the tool enhanced the surface roughness and increased the maximum formability. This study provides an optimal parameter setting for AA8011 and an understanding of the friction stir effect during the incremental forming process.

Effect of Temperature and Strain Rate on Formability of Titanium Alloy KS1.2ASN

Titanium alloys are widely used in aerospace and automotive industries due to their excellent mechanical properties, however, the formability is limited, which is an issue during forming. In the present study, the effect of temperature and strain rate on the tensile properties of the titanium α-alloy KS1.2ASN was investigated. It was observed that there is initially no gain in ductility with increase in temperature until 400 °C, however, maximum formability is reached at maximum tested temperature of 600 °C. EBSD analysis revealed that twinning is the main deformation mechanism at room temperature, however, sliding deformation becomes more pronounced with increasing temperature. An increase in strain rate leads to a decrease in elongation, but the influence is less pronounced compared to temperature.

Experimental investigations of warm incremental sheet forming process on magnesium AZ31 and aluminium 6061 alloy

Aerospace, automobile and biomedical sector focuses on innovative rapid manufacturing processes, which can enable product customization, reduction in cost and manufacturing lead time. Aerospace, automobile and biomedical industries mostly use magnesium AZ31 and aluminium 6061 alloy materials for manufacturing of products because of their lower elastic modulus, excellent corrosion and fatigue resistance. The conventional sheet metal forming processes often require additional tools like punch and die and would not be economically viable to produce the customized structure for applications. An emerging forming technique known as warm incremental sheet forming process is evolved, which is capable of forming intricate, asymmetrical components at elevated temperature with localized deformation method. The characteristics of warm incremental sheet forming process suggest the need for the investigation of magnesium AZ31 and aluminium 6061 alloy materials for wide application of the process. Experimental investigation on the influence of process parameters on warm incremental sheet metal forming of magnesium AZ31 and aluminium 6061 alloy materials using electric heating technique was studied. Experimental results revealed that magnesium AZ31 and aluminium 6061 alloy sheet metal component formed with incremental depth of 0.1 mm, wall angle of 50° and temperature of 300°C showed maximum formability and thickness reduction with minimum geometrical deviation.

Investigation of Forming Behaviour of Metal-Polymer Sandwich Composite through Limit Dome Height Test Simulations

Metal-polymer-metal (MPM) sandwich composites are in the class of proficient engineering materials which give outstanding strength-to-weight ratios because of their comparatively low density. These materials are vital constituents within the automobile, aerospace, marine, and civil construction industries as substitutes for sheet metals that considerably reduce weight while not compromising functionality. Moreover, these materials have supplementary qualities like sound dampening and thermal insulation capabilities. For these materials to be utilized within the aforesaid industries, they need to bear numerous forming processes that are essential in product manufacturing. This paper investigated formability analysis of metal-polymer sandwich composites made of “AW 6082-PVC-AW 6082 (APA)” and “galvanized steel-PVC-galvanized steel (GPG)” sandwich sheets, considering epoxy structural adhesives as the binding agent, via FEA simulation. All the FEA simulations were performed using Altair HyperWorks software. For evaluating the formability, the actual limit dome height (LDH)—biaxial strain path—tests were simulated using FEM software. The results analyzed are forming limit diagram (FLD), punch force distribution, and a dome height at diverse conditions of punch velocity and friction. A comparison is made to represent the best combinations for formability of the sandwich composites. Maximum formability and dome height are attained at low friction conditions and forming speed. It has also been observed that LDH simulations are very sensitive to friction, and it has a substantial impact on the test outputs. Maximum thinning (or fracture) generally moves away from the apex of the dome towards the die corner radius as the friction increases from zero upwards.

Effect of beam current on the microstructure, crystallographic texture and mechanical properties of electron beam welded high purity niobium

Fabrication of superconductive radio frequency (SRF) cavity by electron beam welding (EBW) of pure Niobium (Nb) has been a topic of discussion for quite some time. The influence of beam current on the weld properties of Nb plates has been investigated in light of mechanical properties and microstructure. The widths of the fusion zone (FZ) and heat-affected zone (HAZ) of the welded samples increase with increasing the beam current. The hardness profile across the base metal (BM) to FZ followed a typical symmetrical pattern with a plateau across the FZ. The maximum drop of hardness at FZ compared to BM is only about 15%, making the EBW process a suitable one for the joining of Nb plates for the application of SRF cavity. The development of mechanical anisotropy of the welded joints due to differential heat transfer and the associated change in microstructure in FZ and HAZ has been evaluated by conducting tensile tests along different directions to the line of welding. Elongation of the welded joint is the maximum (~94%) for samples with the tensile direction parallel to the welding direction for a beam current of 70 mA. The Lankford constant (r-value) at different angles (0, 45, and 90°) to the tensile axes has been measured and correlated with crystallographic texture measured by Electron Backscattered Diffraction (EBSD). The dominance of the {554} <225> component for samples with larger heat input is found to be responsible for higher r-values, maximum formability, and lower Kernal average misorientation (KAM) profile. A heat transfer simulation has been used to simulate the dimensions of the weld pool and subsequently correlate its impact on various properties. • Heat input controls the metallurgical phenomena like grain size, hardness and stress-strain response. • The hardness profile decreases from the BM through HAZ until it attains a minimum at the FZ. • Smaller average grain size makes the material stronger and lesser ductile. • Tensile specimens at 0° exhibits deeper and uniformly distributed dimples, an evidence of ductile fracture. • Determine the depth and length of weld pool from the heat-transfer simulation.

Numerical Simulations and Experimental Studies on the Formability of Drawing Quality Steel in Single Point Incremental Forming

Based on numerical simulation and experimental studies the process parameter optimization on the formability using a 1 mm thickness Drawing Quality Steel(CR2) in Single Point Incremental Forming (SPIF)was studied. The sample shape chosen was the hayperbolic cone and fabricated using different parameter leveles. A model of numeric simulation was developed in ABAQUS explicit and then experimentally verified using a CNC milling machine. The influence of three significant control factors, namely tool radius, feeding rate, and step depth on the formability was studied. Optimization of process parameters was conducted using the L9 Taguchi orthogonal array. For optimal formability, to assess the optimum combination of process parameters, a signal noise (S/N) ratio was used. The percentage contribution of the method parameters to formability was determined by the Study of Variance (ANOVA). The findings of the study indicated that the depth of the step followed by feed rate and tool radius, was the dominant factor influencing formability. Furthermore, a good agreement (&lt;8% error) between the numerical simulation and experimental study was seen. The study based on the Taguchi configuration of the study shows that at a feed rate (A2) 1000 mm/min, with tool radius (B1) 8 mm, and with step depth (C2) 0.8 mm, the optimal conditions for maximum formability were achieved.

Effects of process variables optimization on the quality of parts processed in high speed single point incremental sheet metal forming by ranking algorithm

Single point Incremental shaping (SPIF) is a metal forming process which rose to unambiguous quality toward the commencement of the 1990 s. ISF is an exceptionally limited twisting procedure in which a device, modified to take after in a specific direction, moves over a sheet metal and structures the coveted shape and a prosperous process to manufacture sheet metal parts that is well adapted for prototypes or small batch production. On contrast with the traditional sheet forming technologies this is relatively a slow process and is only profitable for the above mentioned production types but it can be used in different applications in automotive and aircraft industries, in architecture engineering and in medical aids manufacturing. SPIF is a die less method of forming which offers high formability. In this study the SPIF, process parameters such as the spindle Speed 1000/1500/2000 (Rpm), Feed 100/300/500 (mm/min), Tool Diameter 8/10/12 (mm) and step down 0.2/0.4/0.6 (mm) at the specimen interface greatly influence in the Cone shaped Mechanical quality such as Maximum Thinning rate (%), Surface roughness (µm), spring back (%) & formability of Forming for Aluminium alloy AA 8011. The aim of the present work is to study these parameters to build up a cone quality, formed by VMC and to carry out a detailed study of these parameters, experiments were conducted by using the L9 orthogonal array. The output parameters such as affecting mechanical and forming quality were analyzed by TOPSIS and ranking was analyzed.

Thermoplastic forming of amorphous metals

Amorphous metals display an extraordinary mechanical strength and elasticity and can at the same time be formed like thermoplastic polymers. These properties make them the ideal material for industrial applications where complex parts have to withstand high mechanical loads. In this work, the thermoplastic formability of amorphous metals is evaluated and discussed in connection to their thermophysical properties. Formability is experimentally assessed in thermoplastic deformation experiments with a constant heating rate, and in isothermal experiments. The results are compared to the theoretical formability values calculated from the thermophysical material properties and found to perfectly coincide. The formability of amorphous alloys can be reliably calculated based on a viscosity measurement in the supercooled liquid region. In isothermal experiments, the maximum formability is obtained at the highest temperatures where crystallization can still be avoided.

Influence of cold-rolling on incremental sheet forming of polycarbonate

ABSTRACTSince product customization is becoming more and more popular, high process flexibility is required in many industrial sectors. Incremental sheet forming shows versatility and its effectiveness can be improved when coupled with other processes to, for example, change the behavior of the material to be processed. This study combines two technologies, i.e. cold-rolling and incremental sheet forming, for the manufacture of thermoplastic components. Polycarbonate sheets were firstly cold-rolled to reach the desired thickness and then formed incrementally, to study how the first process (which modifies the mechanical behavior of the sheets) influences the second one, e.g. in terms of formability limits and forming forces. To this end, an experimental campaign, covering tensile tests and the manufacture of fixed and variable slope angle frusta by single-point incremental forming, was carried out on parent and cold-rolled sheets. The tests point out the correlation between the tensile behavior and some of the main features of the incremental sheet-forming process, like the maximum formability angle, the forming forces, failures and defects. In conclusion, the study provides a critical interpretation of the results to weight up the pros and cons of this integrated polymer sheet forming process.

A Study on Microstructural Evolution in Cold Rotary Forged Nickel-Superalloys: C263 and Inconel 718

C263 and Inconel 718 are precipitation hardenable nickel-superalloys widely used in different sections of a gas turbine engine dependent on their strength and temperature capability. Cold rotary forging is an effective route for manufacturing axisymmetric components with significantly higher material utilisation as compared to machining from conventional hot forgings. This paper presents a study on how C263, an alloy system strengthened by γ’, and Inconel 718, an alloy system strengthened by γ” and δ, deform during the cold rotary forging process and how their microstructures evolve. The two alloys exhibit maximum formability in solution-annealed condition. In this study, both C263 and Inconel 718 were annealed before the cold rotary forging operation. Parts with a 90° bend flange were successfully cold rotary forged from tubular preforms with a wall thickness of 6 mm. For both the alloys, the cold rotary forged parts exhibit significant differences in material properties from the undeformed sections to the most deformed section (i.e. the flanges). Post-forging heat-treatments are required to impart the desired material properties throughout the part. Therefore, appropriate annealing and aging treatments were identified for each of the two alloys. These heat-treatments led to uniform material properties for both deformed and undeformed sections of the cold rotary forged flanges in case of both the alloys.

Hot tensile test for determining the material constant on superplastic 5083Al alloy sheet

Abstract The superplastic alloys are characterized by strain rate sensitivity index (m). Actual values of m depend on temperature, strain rate and grain size. This experiment aims to attain maximum formability by superplastic forming processes in AA 5083 alloy using uniaxial hot tensile test method. To optimize the different material parameters such as maximum elongation, yield stress, temperature, strain rate and strain rate sensitivity index with the help of the uniaxial hot tensile method. An experimental and Finite Element method are adopted, to attain the permeability by achieving the material properties, at various temperatures and various initial strain rate conditions.

Ultrasonic peen forming of aluminum 6061-T6: Energy minimization subjected to maximum formability and surface properties

Minimizing power consumption and enhancement of product quality characteristics are main important aims of sustainable manufacturing process. However, achieving both goals at same time requires comprehensive understanding of process mechanism and having careful control on setup parameters. In the present work, optimization attempt based on response surface methodology (RSM) has been carried out to minimize the energy consumption of ultrasonic peen forming process subjected to desired value of surface roughness, arc height and hardness by finding optimal input setting of indentation depth, vibration amplitude, feed speed and step over. Analysis of variances (ANOVA) has been carried out to obtain the adequacy precision and to find which factor has greatest impact on quality characteristics. Results indicated that step over and vibration amplitude are the most effective factors on forming energy and surface roughness, respectively. On the other hand, the feed rate has greatest impact on arc height and hardness. The optimization results showed setting of 0.07 mm indentation depth, 15 μm vibration amplitude, 1000 mm feed rate and 0.09 mm step over has been selected as an optimal solution causing 2 kJ consumed energy that is less than 50% of maximum energy. In such condition the surface roughness, arc height and hardness improve about 46%, 74% and 29%, respectively. The optimum results have been further verified through a confirmatory experiment and there is good correlation between both approaches.

Analysis of Formability of face-centered-cubic Structured Aluminum Alloy And Hexagonal Closed Packed Commercially Pure Titanium

The continuous demand for light weight and cost reductions, in the aerospace industry lead to development of different metal forming techniques with higher formability. In this study the deforming behaviour of face-centered-cubic Structured Aluminum Alloy and Hexagonal Closed Packed Commercially Pure Titanium under different lubrication condition is analyzed. Due to different types of bonding among atoms in face-centered-cubic Structure and Hexagonal Closed Packed structure exists, this leads to differences in capability of forming to a required shape. As the light weight components are desired for aircrafts, the maximum formability is desirable to achieve a uniform thickness of formed component without reduction of thickness. Generally, formability depends upon forming conditions, crystal structure as well as on coefficient of hardening at room temperature. The parameters which influence the formability are analyzed and optimized. It is evaluated that high temperature deforming improves formability for both materials. It is also evaluated that the tribological conditions varied due presence of lubricant, Hence influence the forming behaviour and formability.

Formability Improvements of DP 1180 Subjected to Continuous-Bending-Under-Tension

There continues to be a desire to incorporate advanced high strength steels (AHSS) into automotive and other applications in order to reduce the overall weight of the final product. However, these materials exhibit limited ductility prior to fracture and require high forming forces. One means to address these concerns, at least in a laboratory setting, is by subjecting the material to continuous-bending-under-tension (CBT). In this procedure, a set of three rollers reciprocate over the gauge length of the specimen while the material is continuously pulled in tension. The adjustable parameters during CBT testing are the roller depth, the crosshead velocity (which applies the continuous, tensile force to the specimen), and the carriage speed for the reciprocating rollers (which is typically set to the highest value possible while maintaining a safe process). The formability improvements obtained through CBT processing are decreased applied force and increased elongation to fracture. The latter is achieved by assuring that during the CBT process the entire gauge length elongates to the maximum possible value before fracture occurs. Past research has shown that the concentrated deformation in the fracture location of a tensile specimen is similar to the deformation over the entire gauge length of a CBT processed specimen. In this paper, a parameter space study of the DP 1180 AHSS is conducted in order to determine the optimal roller depth and crosshead velocity to achieve the maximum formability improvements for this material. The results demonstrate a promising means to improve displacement (approximately four times over that in simple tension) prior to fracture for this AHSS when subjected to CBT processing.

Stakes and solutions for in-plane sheet-metal formability assessment

In body design, Finite Element Analysis becomes an unavoidable step in optimizing forming processes to ensure the feasibility of a specific designed shape. Different failure criteria exist but the Forming Limit Diagram remains the most used criterion. It can be built in a wide variety of forms but the most usual one is composed only of a Forming Limit Curve (FLC) which represents the onset of localized necking limit of sheet metal. FLC is determined experimentally by standardized Nakajima or Marciniak tests. However, both present lots of roadblocks in the accurate determination of product formability limits due to the use of counter-blanks, no linear strain paths and because they are not adapted for high ductility steels. Tensile tests were performed in the past to determine the left hand side of the FLCs. They were not included into the ISO 12004-2 standard because of technical reasons although they present lots of advantages (frictionless, no curvature effect and planar configuration). Now, thanks to the current advanced technologies and tools, these issues are overcome. In this paper, the advantages of tensile tests compared to Nakajima or Marciniak ones are briefly discussed. The design and conceptualization of specific jaws to perform plane strain tensile tests on AHSS are presented. A wide range of AHSS was characterized through plane strain tensile tests and results were compared to formability limits determined by the usual practice using Nakajima tests. Different evaluation strategies were used to determine the maximum formability: the position dependent method, the time dependent one and close to fracture.

Experimental investigations on the incremental sheet forming of commercial steel ASTM A653 CS-A G90 to predict maximum bending effort

Single point incremental sheet forming stands out mainly by using traditional CNC machines to produce small batches of parts or customized products. Thus, any excessive force in the process may compromise the integrity of the machining center or even damage the component itself, limiting its formability. Hence, this work presents the design of experiments to investigate the behavior of mechanical forming forces and optimize the process. The main goal was to build a mathematical function by regression analysis that best represents the theoretical model. The equation proposed here allows to locate and estimate the maximum effort Fz_peak based on five input parameters: tool diameter; wall angle; sheet thickness; vertical step size; and tool feed rate. At the same time, determine the set of data that maximize the required formability. The test was carried out using a carbide coated tool K40 and a commercial sheet steel ASTM A653 CS-A G90. The following were found: the feed rate is not significant and can be maximized to reduce production time; the tool diameter and wall angle are significant, and they have a slight influence on the forces and both depends on the design area; the vertical step size is significant and the most important parameter to leveling the process to reach maximum formability. Finally, the sheet thickness is obviously significant; however, it is also specified by the design.

Formability behavior studies on CP-Al sheets processed through the helical tool path of incremental forming process

Incremental sheet forming (ISF) is a novel die-less sheet metal forming process, which can produce components directly from the CAD geometry using a CNC milling machine at less production time and cost. The formability of the sheet material used is greatly affected by the process parameters involved and tool path adopted, and the present study is aimed to investigate the influence of different process parameter values using the helical tool path strategy on the formability of a commercial pure Al and to achieve maximum formability in the material. ISF experiments for producing an 80 mm diameter axisymmetric dome were carried out on 2 mm thickness commercially pure Al sheets for different tool speeds and feed rates in a CNC milling machine with a 10 mm hemispherical forming tool. The obtained parts were analyzed for springback, amount of thinning and maximum forming depth. The results showed that when the tool speed was increased by keeping the feed rate constant, the forming depth and thinning were also increased. On contrary, when the feed rate was increased by keeping the tool speed constant, the forming depth and thinning were decreased. Springback was found to be higher when the feed rate was increased rather than the tool speed was increased.