Billet Size Research Articles

Billet Size Optimization for Hot Forging of AISI 1045 Medium Carbon Steel Using Zener-Hollomon and Cingara-McQueen Model

This study investigates the effects of initial billet size variations on material flow behavior in hot forging processes, aiming to optimize the forging process using validated predictive models. Material and high-temperature compressive tests inform mathematical models, while simulations are conducted via the finite element method (FEM). Results align with the Zener-Hollomon and Cingara-McQueen approaches. The Arrhenius model predicts AISI 1045 steel flow stress with an R2 of 0.968 and an average absolute relative error (AARE) of 7.079%. The Cingara-McQueen equation achieves an R2 of 0.997 and an AARE of 2.960%. Reducing billets size from 260 mm to 230 mm decreases the material usage by up to 11.5%, while maintaining workpiece integrity. Experimental and simulated loads exhibit an AARE of about 2.69%, thereby indicating potential cost and efficiency improvements in hot forging processes.

Study of CNC skew rolling of hollow rail axles with a mandrel

The manuscript presents a new manufacturing technology for the production of hollow railway axle forgings. The manufacturing technology analyzed is based on three-roll skew rolling (TRSR) using a computer numerically controlled (CNC) rolling mill. The study focused on comparing the rolling capability of hollow products without and with a mandrel calibrating the hole of the forging. The influence of tube billet size on the rolling process was also analyzed. FE analysis and experimental studies were carried out. An analysis of the accuracy of the internal hole of the forging depending on the adopted parameters of the rolling process was carried out. Based on numerical simulations, the state of strain and the flow pattern of the material and temperature distribution during rolling were determined. The force parameters of the rolling process of hollow forgings were also analyzed. Based on the research, a two-stage rolling technology for rolling hollow railway axle forgings was proposed. The results obtained indicate the suitability of using a calibrating mandrel to improve hole accuracy in hollow forgings rolled from a tubular billet. The gap c between the bore diameter of the forging and the diameter of the mandrel was measured. Increasing the tubular billet dimensions from Ø42.4 × 10 mm to Ø48.3 × 12.5 mm reduced the gap c by 49.8%. Rolling the billet Ø51 × 14.2 mm in two passes compared to rolling in one pass reduced the gap c by 45.5%.

Cylindrical Billet Size Optimization for Hot Closed-Die Forging of the Upper Ball Joint

Three-dimensional finite element modeling (FEM) has been carried out using QForm software on the hot forging operation of the upper ball joint, involving the process of roughing and finishing. The material used is SNCM8 commercial alloy steel. This paper aims to optimize the initial billet size to achieve a final forged product without any defects. To accomplish this task, it was necessary to determine the initial optimum billet size by calculating the mass ratio. It is more practical to reduce the length of the initial billet and keep the diameter constant. The initial billet size was obtained by FE simulation by varying the five cases of mass ratio. The minimum dimension of the initial billet, which filled the die cavity without defects, was selected for the tryout experiments. The experimental results supported the FEM results and indicated that the optimum size was ∅48x152.88 mm, which may reduce material waste by 17.65%. Additionally, the forging load during the forging process was investigated. The actual forging load was slightly higher than the experimental one. The forging load showed a maximum error about 10.13%. Finite element simulation by QForm V10.1.6. software is recommended as an efficient tool for predicting the hot deformation behavior of the material during several stages of hot forging, which can save material costs and the cost of trials, leading to enhancements in the manufacturing process.

Application of shaped tube as preform to eliminate the forming defects of ribbed tube in multi-pass drawing

Thin-walled ribbed tube with small-diameter is a newly designed structure, which is used in nuclear fuel cladding. Due to the high precision requirements of nuclear industry applications, the integral forming and precision forming of ribbed tube are the focus of research. However, the forming defects — rib grooves often fail to achieve the precision forming of ribbed tube. Therefore, the two-pass drawing process is designed to realize the integral forming of ribbed tube and the forming mechanism of ribbed tube is analyzed. Further, the effect of round tube as billet on the forming accuracy of ribbed tube is studied. The results show that the rib groove defects are caused by local large deformation and excessive metal flow, which can not be completely eliminated only by changing the billet size of round tube. Based on this, three kinds of shaped tubes as preforms instead of round billet are proposed for eliminating the rib groove defects to realize the precision forming of ribbed tube. The effects of different preform schemes on the forming accuracy, drawing force and stress distribution of ribbed tube are compared and discussed. By selecting the optimal preform scheme and applying it to multi-pass drawing, the completely defect-free ribbed tube is obtained. At the same time, after adopting the appropriate billet size, the rib filling fullness of the tube is further improved and closer to the target size. Moreover, the microstructure of ribbed tube after multi-pass drawing are observed. The martensite and deformation twins appeared due to work hardening and the grain size refinement degree of different positions are different due to different deformation degree.

Effect of process parameters on performance of grooved hot rolling of SAE 4340 steel bars

ABSTRACT SAE 4340 alloy steel is used in structural parts, forging industry, gears and shafts used for power transmission and landing gears of aircraft. Basic production process of the metal bar involves heating the billet in reheating furnace up to 1200°C–1210°C followed by passing it through a pair of grooved rolls in a rolling mill. The roll separating force, driving torque and end crop length are the important issues to be controlled for quality production, maximization of yield, minimization of rolled bar process scrap, safety of mill and reduction in energy consumption. These response parameters depend on several process parameters – rolling speed, billet temperature, reduction ratio (strain), billet size (cross-section area), roll diameter, etc. This paper presents a study on the effect of process parameters on these response parameters during grooved rolling of SAE 4340 steel. Simulation of the rolling process has been attempted using FORGE® Nxt 1.1. The simulated results so obtained have been validated through experimental results obtained in a rolling mill, following statistical tests. Regression models showing relationship between the process parameters and the response parameters have been developed. Significant model-terms have been obtained using analysis of variance.

Effect of process parameters on roll separating force, driving torque and end crop length during grooved hot rolling of SAE 1020 steel

The rolled SAE 1020 steel bars are widely used for production of gears, spindles, camshafts, axles, fasteners, and gudgeon pins etc. Steel industries are striving for productivity and better yield of hot rolled bar products. The roll separating force (RSF), driving torque (DT) and end crop length (ECL) are the important issues to be controlled for quality production, maximization of yield, minimization of rolled bar process scrap, safety of mill and reduction in energy consumption, etc. These response parameters depend on several process parameters – rolling speed, billet temperature, reduction ratio (strain), billet size (cross section area), roll diameter, etc. This paper presents a study on the effect of process parameters on these response parameters during rolling of SAE 1020 steel. Simulation of the rolling process has been attempted using FORGE® Nxt 1.1. The simulated results so obtained have been validated through experimental results obtained in a rolling mill, following statistical tests. Regression models showing relationship between the process parameters and the response parameters have been developed. Significant model-terms have been obtained using ANOVA.

Development of Advanced Technologies for the Production of Innovative Materials with a Submicrocrystalline Structure by Methods of Severe Plastic Deformation

A promising direction for the development of steel and alloy processing processes is the intensification of plastic deformation by creating zones of localization of shear strains not only in the longitudinal but also in the transverse directions of the deformed metal flow. Intensification of alternating deformations along the entire cross-section and, especially, in the axial zone of the billet by creating new deformation schemes is an effective way to increase the physical, mechanical and functional properties of the metal with the maximum approximation of the finished product size to the original billet size. The paper shows that a promising idea is the development of new technological schemes that implement severe alternating deformation in existing metal forming processes. A continuous rolling method of wide strips is proposed, which provides severe alternating deformation with minor changes in the size of the billet. Based on this method, a scheme of continuous rolling of the strip with the intensification of plastic deformation of the metal is designed. The results of computer simulation showed that the new rolling method increases the strain uniformity in height and the value of the strain degree in the plane of symmetry of the billet.

Additive, subtractive, and formative manufacturing of metal components: a life cycle assessment comparison

Manufacturing processes are typically divided into three categories: formative, subtractive, and additive. While formative and subtractive manufacturing processes are considered more traditional, additive manufacturing (AM) is a family of evolving technologies that are rapidly growing with techniques and constraints yet to be explored. In this paper, a life cycle assessment comparison of casting (formative), machining (subtractive), and three AM methods, namely, binder jetting (BJ), powder bed fusion (PBF), and novel bound powder extrusion (BPE) has been performed. To compare each method from the sustainability standpoint, a life cycle assessment was conducted on a double cardan H-yoke, as a case study, focusing on environmental metrics such as water consumption, energy requirements, and CO2 emissions. This study focuses on the environmental effects of the novel BPE process with respect to current traditional manufacturing and AM methods. The case study was divided into two scenarios of the original and topology-optimized H-yoke to investigate the potential environmental footprint reduction by utilizing the capability of AM in generating complex geometries. The results proved that casting, as a formative manufacturing process, is the most environmentally friendly option for large-scale production of the investigated processes. Among the AM technologies that have been studied, PBF was the most environmentally friendly choice when coupled with renewable energy, reducing the total CO2 emission by 9.2% when compared to casting. In contrast, BJ was more environmentally friendly when fossil fuel was assumed as the main source of energy, showing only an 8.7% increase in CO2 emissions. The novel BPE preformed equal to or just short of BJ in all metrics, showing only a 9.4% increase of CO2 emission using fossil fuel compared to the 41.7% increase seen by PBF, with respect to BJ. AM environmental metrics were significantly improved when the topology-optimized part was employed. Machining, as a subtractive method, performed the worst from the environmental perspective due to the initial billet size and the amount of material to be removed (wasted). The production time for each process was analyzed to display the feasibility of producing the cast study part in a mass manufacturing scenario. The LCA case study proves that the increased number of BPE manufacturing steps does not negatively affect the environmental impact of the process, based on current LCA data. However, the BPE process is the most time-consuming process and must be considered when selecting the method of manufacture.

A study on using cold forging process to manufacture bush

This work studied on the feasibility to produce agricultural bush parts using cold forging followed by machining to replace existing processes of piercing operation followed by shaving had been studied. Short tool life of the shaving punch is a major problem for existing processes. From this work, it was found that the maximum force required for cold forging operation is similar to that used on the existing process. Therefore same facility can be employed for a proposed method. A proper selection of billet size was necessary not only to obtain specific shape of final part, but also to yield maximum rate of material utilization. Another factor influencing the process was material flow constraint by cold forging die design. The design with highly constrained would lead to high stress introduced to the part. It is recommended to use forging die design with allow more of free material flow which is expected to improve tool life.

Hot Forging Process Design and Initial Billet Size Optimization for Manufacturing of the Talar Body Prosthesis by Finite Element Modeling

In hot forging industry, the process design and the billet size determination are very crucial steps because those steps directly influence both the product quality and material utilization. The purpose of this paper was to propose a technique used to design the hot forging process for the manufacturing of the talar body prosthesis. The talar body prosthesis is one of the artificial bones, which its geometry is a free form shape. In this study, the Finite Element Modeling (FEM) was used as a tool to verify the proposed design before implementation in a production line. In addition, an initial billet was determined the optimum size in the FEM by varying the mass ratio factor, the diameter, and the length. It was found that the mass ratio factor is a very useful guideline since the optimum size is quite close to the provided size from the guideline. The FEM results showed that the dimensions of the initial billet significantly affect the complete metal filling in the die cavity. Moreover, the optimum size between the diameter and length can reduce the material waste in the hot forging process of the talar body prosthesis. Finally, the experimental results of the hot forging process showed that the proposed process design with the optimum size of the initial billet is achieved in order to manufacture the talar body prosthesis and the material utilization of the new proposed process is improved from the traditional process by 2.6 times.

Analysis of Forming Behavior in Cold Forging of AISI 1010 Steel Using Artificial Neural Network

Cold forged parts are mainly employed in automotive and aerospace assemblies, and strength plays an essential role in such applications. Backward extrusion is one such process in cold forging for the production of axisymmetrical cup-like parts, which is affected by a number of variables that influence the quality of the products. The study on the influencing parameters becomes necessary as the complexity of the part increases. The present paper focuses on the use of a multi-layered feed forward artificial neural network (ANN) model for determining the effects of process parameters such as billet size, reduction ratio, punch angle, and land height on forming behavior, namely, effective stress, strain, strain rate, and punch force in a cold forging backward extrusion process for AISI 1010 steel. Full factorial design (FFD) has been employed to plan the finite element (FE) simulations and accordingly, the input variables and response patterns are obtained for training from these FE simulations. This ANN model-based analysis reveals that the forming behavior of the cold forging backward extrusion process tends to increase with the billet size as well as the reduction ratios. However, decreases in punch angle and land height lead to the reduction of punch forces, which in turn enhances the punch life. FE simulation along with the developed ANN model scheme would benefit the cold forging industry in minimizing the process development effort in terms of cost and time.

Effect of adiabatic heating on microstructure evolution in Ti-6Al-4V during high strain rate forging

The effect of adiabatic heating on microstructure evolution during high strain rate subtransus forging of a Ti-6Al-4V alloy having equiaxed initial microstructure was studied through experiments and modelling. Ø45 × 67.5 mm cylindrical billets with embedded thermocouples were forged at four different α+β temperatures on a Schuler 2100t screw press to evaluate the extent of adiabatic heating in different parts of the billet. In the centre of the billet, the highest temperature increase due to adiabatic heating exceeded the β transus (~1000 °C) during forging. The microstructure of the forged billets was examined for any changes in β phase volume fraction due to adiabatic heating. The forging process was then simulated in Deform 2D/3D software. High strain rate compression testing in the α+β and β temperature fields was carried out using a Phoenix forge simulator to generate input mechanical properties for the model. The effect of the billet size on the α-β phase transformation during forging and post-forge cooling is also discussed.

Friction problems during ECA-pressing

Equal channel angular pressing (ECA-pressing) is an effective process to produce materials with increased mechanical properties and no change of billet size. In the present paper the experimental and finite element analysis results of ECA-pressing investigation were obtained. The influence of contact friction condition on flow nature and stressedly-deformed state of metal during ECA-pressing was studied.

Influence of Contact Friction on the Kinematics of Metal Flow during Equal Channel Angular Pressing

Equal channel angular pressing (ECA-pressing) is an effective process to produce materials with increased mechanical properties and no change of billet size. In the present paper the experimental and finite element analysis results of ECA-pressing investigation were obtained. The influence of contact friction condition on flow nature and stressedly-deformed state of metal during ECA-pressing was studied.

Finite element simulation of relative sliding in hot rolling

In the rolling process, relative sliding happens due to the different velocities between the billet and work rolls. Quantitative evaluations of the relative sliding are essential to the failure analysis and damage prediction of rolls. The velocity and the distance of the relative sliding were evaluated with varying the billet size, the reduction ratio, the friction coefficient, the rolling temperature and speed, and compared between the flat and the caliber rolling. The relative sliding velocity and distance are increased with increasing the billet height, the reduction ratio and the rolling velocity. They are comparable between the flat and the caliber rolling at under-filling condition, and increased significantly in the caliber rolling at over-filling condition.

Parametric Analysis and Optimization of Closed Die Forging of Gear Blank

Objectives: To analyze the effect of change of input parameters on the forging process using industrial component, a gear blank using the technique of FEM. Methods/Statistical analysis: The input parameters of billet shape/size, forging temperature and coefficient of friction between die workpiece interfaces were selected and the simulated experiments were designed using the technique of Response Surface Method (RSM). The simulations were done using Simufact®(MSC Corporation). The results were analyzed on die filling, defects and flash reduction. Findings: The deformation process was observed by defining flow lines and flow particles in the workpiece. The quantitative data from the flow particles gave the standard deviations of all the responses i.e. shear and normal stresses, effective plastic strain, effective stress, effective strain rate, material flow rate, load and die wear. These values were analyzed by using ANOVA and the significant parameters were highlighted. It was concluded that the parameters in the decreasing order of significance were billet size, coefficient of friction and temperature of billet. The graphical results were checked for defects, die filling and flash. Based on the simulated analysis and experimental values, mathematical models have been developed for die wear, effective strain rate and material flow rate with error ranging from 4% to 9%. It was concluded that for a defect free forging, a homogenous deformation and proper material flow with increased die life were important. Application/Improvements: The experimental production runs have shown remarkable improvement in reduction of rejects. The flash has been reduced by 60%, resulting in the saving of material.

Modelling Central Consolidation during Hot Rolling of Cast Products

Extending the range of finished product sizes from a given ingot or concast bloom or billet section is often limited by the minimum area reduction required to ensure effective central consolidation and final mechanical properties. Predicting effective consolidation or level of remnant porosity for a range of steel grade, billet size, pass schedule/roll design and thermo-mechanical conditions has always been an important issue on plant, much more lately in view of recent trends for larger ingots and development of combined forging/rolling strategies. This paper will focus primarily on a fast analytical technique based on roll gap shape and consolidation factors obtained from Finite Element (FEM) Models. New developments based on FEM submodelling are presented briefly. Healing capabilities based on diffusion bonding can be obtained from [1-3].

Computer Simulation of Transformation during TRIP Steel Rod Drawing

Axis pins, shafts and other rod-like parts are some of the main components of units and machines. They are manufactured from steel rods ranging from 7 to 60 mm in diameter after single-pass drawing. Unalloyed carbon steel grades are generally used to produce these items. TRIP steels application is advantageous in terms of achieving new properties when manufacturing steel rods. The initial billet size, the need to take account a transformation in TRIP steel microstructure and a great number of analysed technological conditions make it challenging to apply new materials into rod drawing process. The research aim is to explore the stress-strain state during rod drawing of steel TRIP700. Modified multiscale computer simulation method has been applied. The simulation method takes into account transformation of retained austenite into martensite during plastic deformation. Decreasing of the computational resource intensity and calculation time has been achieved by application of concept of Statistically Similar Representative Volume Element (SSRVE). Comparative analysis of rod drawing micromodels with and without the TRIP-effect simulation has been performed. The analysis showed that a values of equivalent strains in the deformation zone of a TRIP-ignored micromodel was three-four times lower than in a TRIP-factored micromodel. The analysis of simulation results has revealed that, due to a wide contact area with adjacent grains and interaction between microstructure elements, more intensive martensitic transformation occurred within larger grains of retained austenite. The micromodel shown that position and orientation of grains in the deformed TRIP steel microstructure are some of the factors that predetermine transformation of retained austenite. On the basis of simulation results recommendations on preparation of rod drawing conditions have been developed. Developed technological conditions provides ability to obtain: high-plasticity characteristics and high potential strain-hardening capability during exploitation of a future part; maximum strengthening throughout the cross-section of the rod after drawing; high strain-hardening of the surface layer only. The using of SSRVE concept reduced a number of elements within the micromodel in 20 times, while it lowered the calculation time in 16 times.

Effect of billet diameter on hot extrusion behavior of Mg–Al–Zn alloys and its influence on microstructure and mechanical properties

The effect of the initial billet size on the microstructural evolution and tensile properties of extruded AZ61 and AZ91 Mg alloys was investigated using homogenized billets with diameters of 50 and 80 mm. All the extruded alloys exhibit a bimodal structure consisting of fine dynamically recrystallized (DRXed) grains with numerous precipitates and relatively coarse DRXed grains with few precipitates. Although the size and hardness of the fine DRXed grains do not vary with the billet size, using a smaller billet results in a significant reduction in the size and area fraction of coarse DRXed grains because of an increase in the quantity of precipitates. This increase in both the fraction of fine grains and the number of Mg17Al12 precipitates improves the tensile strength of the extruded alloys. This size effect can be attributed mainly to the increase in the strain rate with decreasing billet diameter, which promotes dynamic recrystallization and precipitation during extrusion. The effect of billet size is more pronounced in the AZ91 alloy, which has a high concentration of alloy elements, than in the AZ61 alloy.

Determination of processing power and optimum billet radius of modified backward extrusion by upper bound approach

A recently developed backward extrusion method entitled “modified backward extrusion” was presented using an upper bound analysis. For this purpose deformation area was divided into four distinct zones and a kinematically admissible velocity field for each of them was suggested. Total dissipated power was calculated for the deformation zones and the extrusion power was computed. The correlations of important geometrical parameters with extrusion force and dissipated powers were shown. Finding the initial billet size, a challenging area in the modified backward extrusion method, was discussed and the optimum billet radius was obtained, considering the minimum relative extrusion pressure. Finite element analyses were conducted and the results were compared with the upper bound analysis. Finally, experiments were executed on commercially pure aluminium and a good agreement between upper bound and finite element analyses with experimental values was observed.