Forging Process Research Articles

Graphic Modeling and Equipment used in the Reconstruction of the Original Damascus Steel

Damascus steel was used in the manufacture of swords and hunting knives before medieval times. The original method of the manufacturing of this type of steel has been lost to time. The research set out to create Damascus steel knives reconstituted according to the recipe from documents written many years ago. The study of Damascus steel provided an opportunity to observe in detail the laborious process of manufacturing this material, which involves free forging and pressure welding of different layers of steel to obtain a particularly strong and durable finished product. To carry out this research, two types of steel were selected to create Damascus steel: AISI 1095 and 15N20 steel. During this study, a functional furnace was built, able to contribute by heating the samples to the hot forging process of these two different materials. By applying a complex process of heating and forging and then repeating this process, the layers of steel were welded together, resulting in an extremely resistant material with a unique aesthetic appearance. Sample processing and the laboratory tests were performed on the obtained Damascus steel to evaluate its mechanical properties, including processing the results using Autodesk Inventor Professional 2023 and simulation in Ansys 2023.

Technological simulation of the process of hot forging of two-layer forgings with deep cavities and an inverted cone

Technological simulation of the process of hot forging of two-layer forgings with deep cavities and an inverted cone

Ассортимент изделий из цветного металла раннего железного века поселения Исетское 3 в Нижнем Приисетье

Metal production in the Trans-Ural region in the Early Iron Age is known mainly from materials from the Itkul and Sargat cultures. The article introduces into scientific circulation the largest collection of objects (80 items) made of non-ferrous metal of the Baitovo culture of this period from the settlement of Isetskoye 3, located in the Lower Iset river area. The purpose of the study is to morphometrically characterize and determine the complex typology, as well as to conduct a comparative analysis with synchronous materials. The studied series of items includes weapons (arrowheads), labor tools (knives, a celt, an awl), elements of horse harness (a fragment of a bit), toilet items, jewelry (a mirror, rings, plaques), etc., as well as slags, ingots, and waste bronze foundry production. Preliminary conclusions on production technology were obtained, indicating that stone and clay molds were used for casting. The authors experimentally tested the hypothesis, which was not confirmed, on the possibility of using wooden knife models in the manufacture of clay casting molds. Signs of forging and abrasive casting processing were recorded on several metal objects. Based on their typology and the identified analogies, it was concluded that the complex is characteristic of the Scythian-Siberian cultures and can be dated back to the 7th – 6th/3rd centuries BC, which testifies to the contacts and connections of the Baitovo population with both the western (Itkul) and the eastern metallurgical centers. The presence of slag, a significant amount of bronze casting waste, and mold fragments confirms its local nature, which, however, does not exclude the import of some metal products from other territories.

Response surface methodology and machine learning optimisations comparisons of recycled AA6061-B4C–ZrO2 hybrid metal matrix composites via hot forging forming process

The optimal conditions of applied factors to reuse Aluminium AA6061 scraps are (450, 500, and 550) ⁰C preheating temperature, (1–15) % Boron Carbide (B4C), and Zirconium (ZrO2) hybrid reinforced particles at 120 min forging time via Hot Forging (HF) process. The response surface methodology (RSM) and machine learning (ML) were established for the optimisations and comparisons towards materials strength structure. The Ultimate Tensile Strength (UTS) strength and Microhardness (MH) were significantly increased by increasing the processed temperature and reinforced particles because of the material dispersion strengthening. The high melting point of particles caused impedance movements of aluminium ceramics dislocations which need higher plastic deformation force and hence increased the material's mechanical and physical properties. But, beyond Al/10 % B4C + 10 % ZrO2 the strength and hardness were decreased due to more particle agglomeration distribution. The optimisation tools of both RSM and ML show high agreement between the reported results of applied parameters towards the materials' strength characterisation. The microstructure analysis of Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscope (AFM) provides insights mapping behavioural characterisation supports related to strength and hardness properties. The distribution of different volumes of ceramic particle proportion was highlighted. The environmental impacts were also analysed by employing a life cycle assessment (LCA) to identify energy savings because of its fewer processing steps and produce excellent hybrid materials properties.

Effect of Strontium Modification on Microstructure and Mechanical Property Al12SiCuMgNi Alloy in Squeeze Casting

Abstract The Al-Si series alloys, which have excellent fluidity and castability, are the most common aluminum material in the casting industry. However, the coarse eutectic Si phase with laminar morphology leads to the stress concentration of material and has a detrimental effect on the mechanical properties of aluminum alloy components. In this study, the Strontium (Sr) modifier was added to Al12SiCuMgNi alloy and the effect of Sr on microstructure and performance of Al12SiCuMgNi in squeeze casting was investigated. The experimental results show that the eutectic Si phase was well modified to fibrous morphology. Although the yield strength (YS) was leveled, the ultimate tensile strength (UTS) and elongation (EL) of the alloy were obviously enhanced after Sr addition. When the 0.012wt.% Sr was added to Al12SiCuMgNi alloy. The YS, UTS, and EL of alloys were up to 311 MPa, 401 MPa, and 3.4%, respectively. Moreover, the microstructure and performance of Al12SiCuMgNi alloy in the hot forging process were also compared to Al12SiCuMgNi alloy with and without Sr addition in squeeze casting. It is concluded that the Al12SiCuMgNi alloy in hot forging shows higher ductility (4.7%) and lower strength than Al12SiCuMgNi alloy in squeeze casting.

Effect of aspect ratio on the metal flow behaviour during forming process: A numerical simulation approach

This paper presents results on the effect of aspect ratio on the flow stress of 42CrMo4 steel using Deform™ 3D Version 11 simulation software. The FEM simulation process conditions were upsetting temperature of 1000 °C and 10 s⁻¹ strain rate. The sample aspect ratios (height/diameter) varied within commonly used ranges during conventional Gleeble experimentations. The aspect ratio did not affect the flow stress behaviour during forming. Generally, the forming conditions influence the flow stress-strain field and distribution behaviour, causing inhomogeneous deformation. A negligible effect of aspect ratio on typical industrial forging process is only attainable between 1.0 and 2.0. The implications of the results for industrial forging are elucidated.

Microstructure evolution and mechanical properties of β/γ-TiAl alloy during high-rate near-isothermal multidirectional forging

The microstructure of β/γ-TiAl alloy was characterized and analyzed in various deformation regions during a high-rate near-isothermal multidirectional forging (HR-NIMDF) process in this study. The results indicate that the localized precipitation of the B2 phase occurs within the large lamella microstructure through DRX and heterogeneous exsolution decomposition mechanism in the stagnant zone. The majority of mixed fine-grained microstructures (α2/γ/B2), with a grain diameter smaller than 1 μm, were formed under an appropriate stress-temperature coupling field. In the central region of the large deformation zone, a small twisted lamellar microstructure with low B2 phase content is observed, suggesting that HR-NIMDF can efficiently decompose the (α2/γ) lamellar structure and achieve refined grain microstructures. After undergoing HR-NIMDF, the β/γ-TiAl alloy exhibits a low tough-brittle transition temperature and an elongation of 7 % at 650 °C, with an ultimate tensile strength of 862.6 MPa. At 700 °C, the elongation increases to 55.4 %, while the ultimate tensile strength decreases to 653.8 MPa. Moreover, this study demonstrates that when the plastic deformation degree is insufficient and the adiabatic warming effect is relatively pronounced, significant precipitation of the B2 phase leads to a reduction in DRX extent within the material, ultimately resulting in the formation of large residual (α2/γ) lamellar microstructure. The unsynchronized thermal-force coupling relationship between the precipitation of the B2 phase and DRX holds significant implications for advancing and refining the thermoplastic deformation process of β/γ-TiAl alloy.

Preventing columnar grains growth during hybrid wire arc additive manufacturing of austenitic stainless steel 316L

AbstractWire arc additive manufacturing (WAAM) is an efficient technique for producing medium to large‐size components, due to its accessibility and sustainability in fabricating large‐scale parts with high deposition rates, employing low‐cost and simple equipment, and achieving high material efficiency. Consequently, WAAM has garnered attention across various industrial sectors and experienced significant growth, particularly over the last decade, as it addresses and mitigates challenges within production markets. One of the primary limitations of WAAM is its thermal history during the process, which directly influences grain formation and microstructure heterogeneity in the resulting part. Understanding the thermal cycle of the WAAM process is thus crucial for process improvement. Typically, fabricating a part using WAAM results in a microstructure with three distinct zones along the build direction: an upper zone (thin surface layer) with fine grains, a middle zone dominated by undesirably long and large columnar grains covering more than 90% of the produced part, and a lower zone with smaller to intermediate columnar grains closer to the substrate material. These zones arise from variations in cooling rates, with the middle zone exhibiting the lowest cooling rate due to 2D conduction heat transfer. Consequently, producing a component with a microstructure comprising three different zones, with a high fraction of large and long columnar grains, significantly impacts the final mechanical properties. Therefore, controlling the size and formation of these grain zones plays a key role in improving WAAM. The aim of this work is to investigate the formation of undesired columnar grains in austenitic stainless steel 316L during WAAM and propose a simple hybrid technique by combining WAAM with a hot forging process (with or without interlayer cooling time). This approach targets the disruption of the solidification pattern of columnar grain growth during deposition progression and aims to enhance the microstructure of WAAM components.

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%.

Markedly enhancing mechanical properties of powder metallurgy superalloy by hot oscillatory forging

A powder metallurgy superalloy prepared by hot pressing (HP) was forged under static and oscillatory pressures. The microstructure, mechanical properties and fracture behavior of the sample before and after forging were characterized in detail. The results showed that the forging processes could effectively break the prior particle boundaries (PPBs) and reduce the PPBs precipitates, thus significantly improved the mechanical properties of the material. In particular, the hot oscillatory forging (HOF) process increased the tensile elongation and stress rapture life of the hot forged sample by 1.3 and 3.5 times, respectively. The present study suggests that HOF could be a promising technique for preparing high-performance superalloys.

Quantification of static softening process and its effects on work hardening characteristics of a typical high strength steel during multi-pass deformation

Heavy components of 300 M steel are usually manufactured by multi-pass forging. It is necessary to study the flow characteristics of 300 M steel during multi-pass deformation, which helps to regulate the flow behaviors during the actual forging process. In the study, multi-pass compression experiments are conducted on the Gleeble-3500 device to mimic the forging process of 300 M steel. Results show that the deformation parameters and inter-pass holding parameters can affect the work hardening rate significantly. It can be ascribed to coupling effects of dynamic softening and static softening behaviors. A unified static softening kinetics model is established to evaluate the coupling effects of static recovery, static recrystallization, and metadynamic recrystallization on the static softening behaviors. The established static softening kinetics model shows high prediction accuracy with a reliability of 0.99605. Furthermore, a new constitutive model is established to describe the effects of dynamic softening and static softening on the flow stress during multi-pass deformation. The prediction accuracy of the new constitutive model is 0.98897 with a mean absolute error of 4.075%, which demonstrates that the established constitutive model is reliable.

Hot deformation behavior and hot working map of Mn–Cr–Ni–Co steel for ball mill liner forging process

To explore the thermoformability of Mn–Cr–Ni–Co steel for ball mill liner, isothermal compression tests were performed on Mn–Cr–Ni–Co steel using a Gleeble-3800 thermal compressive testing machine. Flow stress curves at 900 °C–1200 °C and 0.01s−1∼10s−1 were obtained. Results show Mn–Cr–Ni–Co steel has obvious positive strain rate sensitivity, with peak stress decreasing with increasing temperature. A constitutive equation for Mn–Cr–Ni–Co steel was established using the Arrhenius model based on strain compensation, and fitted values were compared to experimental values. A hot working map for Mn–Cr–Ni–Co steel was established and analyzed. Hot working process parameters are: deformation temperature of 980∼1200 °C, strain rate of 0.04–1.78s−1, providing a basis for selecting the hot forging process of the ball mill liner. Forging and forming experiments of the ball mill liner were carried out using the optimal parameters of Mn–Cr–Ni–Co steel from the hot working map. The ball mill liner has good forming quality with a relatively uniform martensitic structure inside. Tensile and impact tests were performed on the ball mill liner. Compared to the mechanical properties of traditional cast Mn13 ball mill liners, results show the tensile strength increased by 159.75%, elongation by 18.8%, and impact capacity by about 16.7%.

Kink-mediated high strength and large ductility via nanocrystallization in a tough titanium alloy

Titanium (Ti) alloys, which are highly promising as structural materials in critical industrial applications, generally require high strength and ductility, particularly high fracture toughness. However, the conventional approach of enhancing strength through mechanical processing to induce dislocations often leads to a compromised ductility known as the strength-ductility trade-off. Here, we develop a new strategy of the nanocrystallized kinks to overcome this issue in Ti-11V metastable β-Ti alloys via combining industrially used cold forging (CF) and cold rolling (CR) processes. Deformation kinks are firstly activated by CF, and subsequently they are fragmented into nanograins during CR, architecting nanocrystallized kinks in the coarse-grained matrix. This unique microstructure effectively balances the strength-ductility conflict, endowing this Ti-V binary alloy with high yield strength ∼1200 MPa, appreciable ductility ∼17 % and high fracture toughness ∼ 52.0 MPa·m½, which is superior to numerous multielement engineering Ti alloys. This design strategy of nanocrystallized kinks can be extended to other engineering materials, e.g., Mg and Zr alloys, for advanced performance at large industrial scales.

Investigation of the Penetration Performance of the Radial Forging Process for Wrought Aluminium Alloy.

With the wide application potential of wrought aluminium alloy in aerospace, automobile and electronic products, high-quality aluminium bars prepared by the radial forging (RF) process have received extensive attention. Penetration performance refers to the depth of radial plastic deformation of forgings, which is the key factor in determining the quality of forging. In this work, the penetration performance of the radial forging process for 6063 wrought aluminium bars is investigated by simulation using FORGE software. The minimum reduction amount of the hammer is calculated based on the forging penetration theory of forging. The influence of process parameters including forging ratio (FR) and billet temperature on the effective stress and hammer load in the RF process are investigated. The RF-deformed billet is then produced with the optimal process parameters obtained from the simulation results. The average grain size of aluminium alloy semi-solid spherical material is used to evaluate the forging penetration. Simulation results showed that the effective strain at the edge and the centre of the RF-deformed billet gradually increases, but the increasing speed of the effective strain at the edge becomes low. The hammer load first decreases quickly and then gradually maintains stability by increasing the FR. It is found that low billet temperature and high FR should be selected as appropriate process parameters under the allowable tonnage range of RF equipment. Under an isothermal temperature of 630 °C and a sustaining time of 10 min, the difference in the average grain dimension between the edge and the centre positions of the starting extruded blank is 186.43 μm, while the difference in the average grain dimension between the edge and the centre positions of the RF-deformed blank is 15.09 μm. The improvement ratio of penetration performance for the RF-deformed blank is obtained as 91.19%.

A new tube forging process for manufacturing hollow parts with inner flange at an arbitrary location

The forging of hollow parts faces a great challenge as folding and buckling always occur during the forging process. To overcome these problems, a novel tube forging process combining upsetting and shear forging is developed to manufacture hollow parts with an inner flange at an arbitrary location. Firstly, two flow modes are introduced to analyze the deformation behavior of a hollow cylinder during internal thickening by upsetting, where the geometric limits associated with different deformation modes and the critical upsetting ratio with no folding defects are determined. The results clearly show the occurrence of a mode transition for some cylinders during the upsetting process; furthermore, the cylinder is less prone to folding in some cases due to the appearance of a third deformation zone located mid-way up the cylinder. Then, the forming mechanism of this novel process is analyzed, and its feasibility is demonstrated through finite element simulations and experiments. Results show that the flange can be moved to an arbitrary location on the inner wall in the height direction by controlling the stroke of the punch, and shear deformation can enhance the strength of the flange. Additionally, it is found that the shear depth, corner radius of the counter punch, and supporting force on the counter punch are the key parameters affecting the product quality.

Processing heterogeneously structured oxide-dispersion-strengthened Fe-10Cr-6.1Al-0.3Zr-0.1Y alloy for simultaneously enhanced strength and ductility

An oxide-dispersion-strengthened (ODS) Fe-10Cr-6.1Al-0.3Zr-0.1Y alloy with a bimodal grain size distribution was developed via a simple process of internal oxidation and powder forging. The intentionally promoted heterogeneous microstructure consists of coarse-grained “core” regions enclosed by mutually connected fine-grained “shell” zones, facilitated by unevenly distributed oxide particles. The sample sintered and then forged at 1150 °C exhibited a yield strength of 598 MPa, a tensile strength of 734 MPa, and a fracture elongation of 25.1 %. Such simultaneously enhanced strength and ductility are significantly above those of cast or previous powder-consolidated counterparts. During tensile deformation, a strain gradient is built up across the inhomogeneous grains and a high density of geometrically necessary dislocations was observed near the interfaces of matrix/oxide particles, both contributing to heterogeneous deformation-induced strengthening. This elevates the work hardening rate and consequently the tensile elongation. Quantitative analysis indicates that the dislocation build-up during forging makes the dominant contribution to the high yield strength of Ox-1150. The present study offers a new route to the preparation of heterogeneously structured ODS Fe-Cr-Al alloys and provides guidance for optimizing the mechanical properties of such alloys in terms of strength-ductility synergy.

СУЧАСНИЙ СТАН РОЗВИТКУ РОЗВИТКУ ПРОГРЕСИВНИХ ПРОЦЕСІВ КОВКИ

With the vigorous development of high-tech industries such as aviation and aerospace, new challenges have been brought to the traditional forging process. Forgings with a single structural feature and conventional forging processes in the past can no longer fully meet the development of contemporary industry. Therefore, it is urgent to develop new forging processes to meet the higher requirements for forgings. First of all, this article classifies the traditional forging processes, which helps to better understand the different types of forging processes. Then, the analysis of different types of forgings and their forming processes will help to better understand the forming characteristics of different methods of improvement. Comparative analysis found that the selection of forging process and route should fully consider the shape and size of the forgings. In actual production, often one type of forging may have multiple types of shape features. The complexity of the structure makes it impossible to obtain such forgings through only one type forging process or one-step forging. Greatly increased the difficulty of forging, limiting its development and application. Therefore, It is necessary to develop multi-types and multi-steps forging processes. And it is urgent to do further research on the metal forming mechanism and defect generation mechanism of complex forgings in the forging process.

FEM and machine learning aided modelling of compressive deformation anisotropy in pressure-less sintered Cu-15Ni-8Sn alloy

Pressure-less sintering integrated forging is an effective method for densification enhancement of powder metallurgy (PM) processed Cu-15Ni-8Sn alloy. Nevertheless, compressive deformation anisotropy associated with uniaxial forging creates heterogeneous deformation zones containing residual porosity, resulting in strength degradation of the PM alloy. This work introduces a novel approach for mitigating the anisotropy arising from forging by characterising the compressive deformation heterogeneity using a synergy of finite element method (FEM) and machine learning (ML) approaches. Results obtained from Gurson model-based FEM simulation of uniaxial forging process indicate that decreasing the aspect ratio (AR) of sintered preform leads to reduction in plastic deformation heterogeneity. Additionally, the semi supervised ML framework developed here unravels three distinct strain hardening regimes and predicts an upward paradigm shift in the quantitative distribution of instantaneous strain hardening exponent with the decrease in AR. These computational predictions align with the experimental forging results which demonstrate substantial enhancement in strain hardenability, formability and densification of lower AR preform due to more uniform deformation. Uniaxially forged compact depicted a notable increase of 14 % in relative density along with significant improvement in hardness by 66 % as compared to the sintered compact, which can be attributed to forging induced pore elimination at microstructural level. The promising results obtained in this study have practical implications in the development of sustainable green manufacturing technology to produce high strength porosity tailored Cu-15Ni-8Sn alloy.

A low-cost Mg–Al–Mn–Zn alloy for automotive road wheel applications

In this study, a new Mg–Al–Mn–Zn alloy (AMZ211) was designed, aided by thermodynamic modeling, for applications in automotive road wheels using forging and flow-forming processes. The AMZ211 alloy was cast and forged in an industrial scale to obtain a forged blank to evaluate its tensile properties and hot formability under high-strain-rates (simulating flow-forming conditions). Multiple characterization techniques, including optical, scanning electron and scanning transmission electron microscopy as well as electron backscatter diffraction, were applied to investigate the microstructural evolution during the processing route. As expected from the alloy design, nano-sized Mn-containing dispersoids formed in a homogeneous manner during homogenization heat treatment, contributing to the formation of refined dynamically recrystallized (DRXed) grains in as-forged microstructure. The as-forged AMZ211 alloy showed better hot formability than as-forged AZ80 Mg alloy under high-strain-rate condition as well as a comparable strength property in relative to the benchmark and more expensive Mg–Zn–Zr alloys. The lower ductility of as-forged AMZ211 alloy may be due to the high twinning tendency of coarse unDRXed domains which were formed as a result of the original coarse-grained microstructure from solidification. The present study provides a low-cost Mg alloy for high-volume automotive road wheel applications.

Optimization of hot deformation parameters for multi-directional forging of Ti65 alloy based on the integration of processing maps and finite element method

In this paper, the hot deformation behavior of Ti65 alloy was investigated over the temperature range of 930–1110 °C with the strain rate of 0.001–1 s−1. According to the stress-strain curves, the constitutive equation was developed to describe the flow behavior of Ti65 alloy. The processing maps were constructed based on the dynastic materials model (DMM) and the perfect formability zone of Ti65 alloy is found under the temperature of 970–1020 °C and the strain rate of 0.001–0.1 s−1. In addition, a three-dimensional nonlinear transient thermo-mechanically coupled finite element model of the multi-dimensional forging (MDF) process of Ti65 alloy was developed. The effects of the forging temperature and forging speed, on the temperature rise, residual stress, and grain refinement were predicted. By analyzing the temperature and stress distribution, the optimum forging temperature and speed for Ti65 alloys were determined to be 1000 °C and 10 mm/s, respectively. Increasing the forging temperature or reducing the forging speed reduces the temperature rise and the maximum tensile stress, thus reducing the risk of cracking. Additionally, the equivalent strain increases as forging speed decreases. Simultaneously, the accumulated strain is more significant for the inside of the forgings. The results of this research are instructive for the optimization of the MDF process.