Rolling Process Research Articles

Micro-alloying of Sm with rolling for synergetic corrosion resistance and mechanical properties of Mg-Al-Sn-Ca-Mn alloys

Micro Sm alloying coupling with four-pass rotary rolling is conducted to synergize the corrosion resistance and mechanical properties of Mg-Al-Sn-Ca-Mn alloys. Micro Sm alloying weakens the galvanic corrosion. Rolling process refines the grains, intensifies the basal texture and promotes dispersed second phase particles, thereby contributing to forming a uniform and protective corrosion product film, and enhancing the mechanical strength and ductility. As a result, rolled Mg-Al-Sn-Ca-Mn-Sm alloy exhibits a synergy of mechanical properties and corrosion resistance, i.e., an UTS of 271 MPa, YS of 204 MPa, elongation to failure of 18 %, and a low corrosion rate of 0.85 mm y−1.

Characterization of Industrial Carbon Emission Dynamics and Network Structure Evolution in China

Given that industry is the major source of carbon emissions, clarifying the carbon transfer regularity triggered by industry production linkage is of great importance in realizing the synergistic development of industry to reduce pollution and carbon emissions. Based on the perspective of responsibility allocation, the study accounted for the industry carbon emissions and constructed a carbon transfer weighted directed network model and applied the social network analysis method to explore the structure of the industry carbon transfer network and its evolution characteristics from 2005 to 2020. The results showed that： ① The overall carbon emissions of industries from 2005 to 2020 presented a rapid growth trend and large differences occurred in emissions between industries. ② The scale of the carbon transfer network was expanding rapidly and the characteristics of the small-world network were significant. ③ The community structure of the carbon transfer network was obvious, including four optimal associations： high carbon emission, carbon transmission, carbon endogenous, and high spillover. ④ The construction industry and the metal smelting and rolling processing industry were the core of the carbon transfer network structure, with strong network control. In view of the above characteristics, we proposed countermeasures and suggestions in terms of implementing the allocation of carbon emission reduction responsibilities and differentiated emission reduction measures for associations as well as focusing on the management of core nodes of the network, with the intent of providing cross-sectoral synergistic emission reduction ideas for the development of sustainable low-carbon transformation in China's industry sector.

Study on the uniaxial tensile mechanical behavior and constitutive model of advanced high-strength steels for DP1180 and Q&P1180

With the increasing global demand for green and environmentally friendly materials, advanced high-strength steels (AHSS) produced using by cold rolling process are gaining more attention in the construction industry, such as in cold-formed thin-walled structures. To expand their engineering applications, the study of the mechanical behavior and constitutive models of AHSS is particularly important. This paper focuses on DP1180 and Q&P1180, employing experimental research and theoretical analysis to elucidate the patterns at various characteristic points and establish constitutive models for AHSS. The specific conclusions are as follows: 1) For DP1180 and Q&P1180, the average elongation after fracture is 8.9 % and 16.7 %, respectively, with strength-to-yield ratios ranging from 1.24 to 1.34 and 1.14–1.24, respectively. 2) Due to the insignificant nonlinearity exhibited by DP1180 and Q&P1180 near the nominal buckling strength, the modified nominal yield strength and equivalent ultimate strength was defined and adopted as the boundaries to divide the stress-strain curve into three segments. The mathematical expressions and relevant parameter models for each segment are established. Finally, the three-stage AHSS uniaxial tensile constitutive model was established. Compared to existing models, the proposed model demonstrates higher accuracy.

Bending properties and deformation micromechanisms of near-α titanium alloy sheets/foils considering initial texture characteristics and size effect

Clarifying the bending deformation behaviour of metal foils is essential for meeting the lightweighting requirements of metal honeycomb structures. This study selected Ti65 alloy specimens with various thicknesses and initial α-phase textures to conduct room-temperature three-point bending experiments. A detailed comparative analysis was performed on the bending deformation behaviour of Ti65 alloy sheets and foils. It reveals that in the foil specimens, the weakening effect of surface layer grains is significant. Under the influence of size effects, the springback angle of Ti65 alloy foils with coarse α-phase grains decreases markedly. Additionally, through various methods, including global Schmid factor analysis, lattice rotation analysis, and crystal plasticity finite element method simulations, the specific relationship between α-phase texture and the bending performance of Ti65 alloy foils was thoroughly investigated. The rolling process influences the bending performance of Ti65 alloy by determining the α-phase texture. Unidirectionally rolled Ti65 alloy products exhibit a transverse α-phase texture, which predisposes them to form transverse texture α-phase macrozones during bending. In contrast, cross-directionally rolled Ti65 alloy foils possess a basal α-phase texture biased toward the transverse direction. This not only helps avoid the formation of macrozones but also ensures coordinated deformation across the foil, resulting in superior bending performance.

Analysis of fatigue damage of hot rolling work rolls coupled with wear effect

During the hot rolling process, the work roll experiences cyclic contact stress due to the deformation of the strip steel, as well as thermal stress from periodic heating and cooling. The surface failure of the work roll results from the combined effects of wear and fatigue damage. This study proposes a comprehensive approach to analyzing coupled wear and fatigue damage using a method based on the Manson-Coffin equation, modified slope formula, and the Miner criterion. Finite element models were developed to simulate simplified heat transfer and thermal coupling, taking into account the actual rolling parameters and high-temperature material properties of the work roll. The evolution of the physical field of the work roll during the rolling process was analyzed. The analysis of these models revealed that the maximum strain on the work roll occurred at the rolling exit and was predominantly influenced by temperature. The effects of rolling speed and temperature on work roll strain varied, with fatigue damage being significantly reduced when wear was considered compared to scenarios where wear was not accounted for, under the same number of cycles.

Surface fatigue characterization and its enhancement by the engineered ultrasonic rolling process for 300 M ultrahigh strength steel

The fatigue life of surface layer (FSL) is innovatively characterized to accurately capture the effect of surface integrity on the fatigue behavior of the components. The sensitivity of FSL of 300 M ultrahigh strength steel to the surface integrity indexes induced by representative manufacturing processes was analyzed by analytical modeling and fatigue tests from the perspective of engineering fracture mechanics. The ultrasonic surface rolling process (USRP) was introduced to optimize the fatigue limit of 300 M steel, and the improvement in fatigue life was experimentally quantified. Besides, the fracture analysis was conducted to provide the reason why USRP can enhance the fatigue behavior of 300 M steel. The results show that FSL occupies a majority with percentage of over 95 % in the entire fatigue life and a strong relation with the machined surface defects, especially the surface machining marks. The excellent surface finishing effect and high compressive residual stresses induced by engineered USRP could transfer the crack source from surface machining marks into subsurface inclusions, which greatly prolongs the fatigue crack initiation life and thereby the entire fatigue life. To be specific, the fatigue life was elevated by more than 40 times and the fatigue strength was increased by 34.7 % after USRP for the tested 300 M steel.

Simulation study of turning-ultrasonic rolling compound processing for 42CrMo steel

The ultrasonic rolling processing technology has been shown to significantly reduce surface roughness and enhance the residual stress of parts, thereby improving their surface properties and extending their service life. This technology is particularly effective for the precision machining and surface strengthening of ultra-high-strength steel 42CrMo. This study aims to investigate the impact of turning pre-processing on the distribution of residual stress during ultrasonic rolling, a simulation model incorporating turning pre-processing was developed and used to conduct ultrasonic rolling simulation experiments, enabling the analysis of residual stress distribution patterns. Concurrently, ultrasonic rolling strengthening experiments were performed to validate the accuracy of the simulation model. The results confirm that with increasing rotational speed and feed rate, residual stress decreases, whereas with increasing static pressure and amplitude, residual stress increases. The residual stress variation obtained from the simulation of combined turning and ultrasonic rolling closely matched the results of experimental ultrasonic rolling tests. This consistency validates the accuracy of the simulation model. This study offers a novel approach for simulating and experimentally validating ultrasonic rolling processes, particularly for shaft-like parts that undergo turning as a pre-processing step.

Microstructure and properties controlling of Al-xGd alloys for thermal neutron absorbing

A novel lightweight thermal neutron absorbing Al-xGd alloy (x = 2.5, 5, and 10 wt.%) with tunable mechanical properties was fabricated by induction melting followed by a rolling process and an annealing treatment. During solidification, the Al3Gd phase predominantly formed and was distributed along grain boundaries. Cold rolling crushed and redistributed the Al3Gd phase throughout the matrix. Furthermore, the large deformation imposed on the material during cold rolling enhanced the work hardening effect and promoted dynamic recrystallization. The load transfer strengthening effect was influenced by the size, volume fraction, and distribution of the second phase. The spheroidization of the second phase increased rapidly and then remained stable during 5000 h long-term aging at 400°C. The thermal neutron absorbing performance of the Al-5Gd alloy is comparable to the 30%B4C/Al composite evaluated by Monte Carlo simulations. Furthermore, Al-5Gd alloy exhibited higher plasticity (> 20%). This novel Al-xGd alloy is a promising candidate for future lightweight thermal-neutron-absorbing materials.

Effects of Temperature and Water Pressure on Mild Steel Strength: A Comparative Study

This study delves into the dynamic realm of mild steel strength variations under the influence of temperature fluctuations and alterations in water pressure during the rolling process. With a focus on elucidating the nuanced relationship between these factors and steel durability, the research employs a systematic investigation approach. The experimental design involves controlled temperature adjustments and varying water pressure scenarios to assess their impact on the structural integrity and tensile strength of mild steel. Through meticulous analysis and measurement, the study aims to uncover the intricate interplay between temperature, water pressure, and steel strength, providing valuable insights for optimizing rolling processes in industrial settings. The experimental works have been conducted at 870°C, 890°C, 910°C, 930°C, 950°C of temperature and 5.800 Kg, 6.000 Kg, 6.200 Kg, 6.400 Kg, 6.600 Kg of water pressure. At 870°C, 890°C, 910°C, 930°C, 950°C of temperature, the yield point values are 548 Mpa, 541 Mpa, 533 Mpa, 525 Mpa and 520 Mpa respectively. At 5.800 Kg, 6.000 Kg, 6.200 Kg, 6.400 Kg, 6.600 Kg of water pressure, the yield point values are 521 Mpa, 527 Mpa, 534 Mpa, 538 Mpa, 544 Mpa. The Yield Load, Yield Strength, Maximum Force, Tensile Strength, TS/YS Ratio, and Elongation after Fracture were carried out in the Metrocem and Mohammadi Steel Works Ltd (MSW) laboratory. However, the results of two laboratories are almost similar. The findings aspire to contribute to enhanced manufacturing techniques and the development of more resilient steel products, thereby advancing the understanding of material behavior in mechanical applications.

Effects of carbon levels and surface area variations on mild steel strength: A comparative study

This study investigates the dynamic interplay between carbon levels and surface area variations on mild steel strength during the rolling process. Focused on understanding the nuanced relationship between these factors and steel durability, the research adopts a systematic approach. Controlled adjustments in carbon levels and surface area variations are employed to assess their impact on the structural integrity and tensile strength of mild steel. Through rigorous analysis and measurement, this study aims to unveil the intricate connections between carbon content, surface area alterations, and steel strength, offering critical insights for optimizing rolling processes in industrial settings. The experimental works have been conducted with carbon levels variations and surface area variations. The samples were tested in two different laboratories, however, the results of two laboratories are almost similar. The higher carbon content increases strength and yield strength varies with different carbon level and surface area. The surface area variations are affected the mechanical properties of mild steel. The maximum stress recorded was 700 MPa and the breaking point observed at 540 MPa. The findings aspire to contribute significantly to refining manufacturing techniques and developing more resilient steel products, thereby advancing our comprehension of material behavior in mechanical applications.

Study on the mechanical properties and microstructures of Al-Cu-Mg alloy thick plates obtained by different hot rolling processes

Abstract In the research, the microstructures of large-scale 2324 aluminum alloy thick plates obtained through two different hot rolling processes are investigated by using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD). Additionally, the tensile properties of the plates are evaluated at room temperature. The results indicate that the thick plates produced by Process A exhibit higher tensile and yield strengths along the L (longitudinal) and LT (long transverse) directions. The higher proportion of deformed microstructures is an important factor contributing to their enhanced tensile and yield strengths. Meanwhile, the different rolling processes have minimal impact on the kind and distribution of the second phase in the hot-rolled thick plates, with the second phase primarily consisting of Al2Cu and Al2CuMg phases, which are distributed in a streamlined way along the rolling direction of the thick plates. The microstructures of the hot-rolled thick plates obtained from both hot-rolling processes are dominated by deformed structures. The thick plates produced by Process B have relatively smaller grain sizes and a higher degree of fragmentation, making their microstructure more susceptible to recrystallization transformation during subsequent solution heat treatment.

Influence of the rotational speed ratio of rollers on the three-dimensional surface rolling process

Influence of the rotational speed ratio of rollers on the three-dimensional surface rolling process

Microstructure evolution by thermomechanical processing and high-temperature mechanical properties of HCP-high entropy alloys (HEAs)

The solid solution strengthening and deformation mechanisms of the hcp-high entropy alloys (HEAs) have not been elucidated yet because of the complexity introduced by the martensite structure, particularly in alloys undergoing phase transformation from bcc to hcp structures. This study attempted to fabricate an equiaxed hcp microstructure for TiZrHf, TiZrHfAl, and TiZrHfAlSc using the hot rolling process and subsequent heat treatment. The equiaxed hcp phase was successfully formed in TiZrHfAl, but the martensite structure remained in TiZrHf and TiZrHfAlSc. The 0.2 % proof stress at 400 and 600°C increased with the increase of the average atomic size misfit δ and the mixing entropy . The low activation volume and high-stress exponent of TiZrHfAl with equiaxed hcp phase at room temperature suggest minor obstacles such as cluster or short-range order inhibit the movement of dislocation and leading to the significant solid-solution strengthening. However, the effect diminished at 600 °C.

Ultrahigh strength – ductility in Ti–6Al–4V composites with high-activity graphene-induced in-situ TiC and coherent nanophases

Achieving ultra-high strength and ductility of titanium alloys possesses great potential for structural applications in the aerospace and military, yet there is a great challenge for breaking the trade-off barrier of these two properties. In this study, large elongation of ∼10 % and ultra-high tensile strengths of 1510 MPa were obtained in a titanium-based composite. We designed this superior composite based on nanoscale coherent αʹʹ precipitation within near-equiaxed β-Ti as well as micro-scale TiC network architectures along grain boundaries. These in-situ formed triangular αʹʹ coherent precipitates and TiC mainly contributed to the strengthening, while the extremely large elongation resulted from coherent β/αʹʹ interfaces and strain-induced coherent αʹʹ nanotwins. We demonstrated that this composite was easily fabricated using a simple powder metallurgy followed by a hot rolling process. This work can contribute to the design of duplex titanium-based composites as well as other structural materials with exceptional mechanical properties for broad applications.

Quantitative mechanism of abnormal hardening behavior of Ti6Al4V alloy strengthened by ultrasonic surface rolling

In general, the outermost region of a metallic material has the highest hardness after surface mechanical strengthening. However, an abnormal surface hardening behavior was observed in Ti6Al4V alloy after the ultrasonic surface rolling process (USRP) in this work. The region with the highest surface hardening was not at the top surface but at the subsurface. By analyzing the distribution of grain size, dislocation density, texture, and kernel average misorientation (KAM) at different depths from the surface, and combining these findings with finite element analysis (FEA), the microstructural evolution underlying this abnormal surface hardening was elucidated. The microstructural characterization and FEA results indicate that the subsurface region underwent the most significant deformation. Subsequently, through the application of theoretical analysis, the potential mechanism of abnormal hardening of USRP treatment is described quantitatively for the first time. The results demonstrated that the hardening effect resulting from grain refinement was less pronounced, whereas the hardening effect resulting from dislocation pile-up was more prevalent. At the subsurface region of the USRP sample, a large number of interfaces resulted in the highest accumulation of dislocations in this area. Consequently, the subsurface region exhibited the highest microhardness, leading to the abnormal surface hardening phenomenon.

Ameliorating the microstructure and properties of a Cu[sbnd]Cr alloy by introducing a high-temperature short-time treatment into the thermo-mechanical process

The optimization of process is essential for improving the overall properties of high-strength and high-conductivity Cu alloys. This study introduces a high-temperature short-time treatment (HTSTT, 850 °C/5 min) into the thermo-mechanical process of a CuCr alloy. Following the process of “solid solution - cold rolling - HTSTT - cold rolling - aging”, the tensile strength of the alloy increases from 450 MPa to 508 MPa, with the electrical conductivity increasing from 82.2 %IACS to 86.4 %IACS when compared to the conventional process of “solid solution - cold rolling - aging” under the same total deformation condition. The reasons for the improvement in the comprehensive properties of the alloy after introducing HTSTT are analyzed through microstructural characterization. The results indicate that the HTSTT promotes the occurrence of recrystallization, leading to grain refinement, which results in smaller grain sizes during subsequent processing. Additionally, the introduction of HTSTT changes the main texture of the alloy from 〈100〉//X to 〈111〉//X during the process, which is beneficial to enhancing the alloy's strength and electrical conductivity. More importantly, the HTSTT facilitates the precipitation of solute Cr atoms, leading to the formation of a significant quantity of nanoscale Cr particles, most of which are spherical with an average size of 27 nm. During the subsequent cold rolling process, these Cr particles effectively pin dislocations and promote their proliferation, leading to the precipitation of a large number of smaller Cr particles during the aging process, with an average size of 4.8 nm. These finer Cr particles are crucial for precipitation strengthening. This paper offers valuable insights into the microstructural optimization and performance enhancement of high-strength and high-conductivity Cu alloys.

La drives the remarkable strength enhancement of the Cu-Cr-Zr alloy through traditional thermo-mechanical treatment

The Cu-1Cr-0.1Zr alloy with different La addition (0 %, 0.07 % and 0.14 wt%) was processed using industry suitable two-step cold rolling and aging treatment to achieve superior strength and electrical conductivity. The role of La addition on the microstructure evolution and comprehensive properties of the Cu-1Cr-0.1Zr alloy is investigated during the second rolling and subsequent aging stages. During pre-aging process, the presence of La in the Cu-1Cr-0.1Zr-0.07La alloy led to formation of smaller precipitate sizes compared to La-free Cu-1Cr-0.1Zr alloy. This facilitates a stronger cut interaction between dislocations and precipitates during secondary rolling process, which promotes the redissolution of precipitates into Cu matrix and thus results in a larger decline of 44.72 % ICAS for the electrical conductivity of Cu-1Cr-0.1Zr-0.07La alloy. After post-aging treatment, precipitates are newly formed with increased number and refined size of Cr precipitates with maintaining a coherent relationship with the matrix. Besides, the addition of La promotes Cr-rich phase precipitation and dislocation accumulation. Resultantly, remarkable increase in tensile strength by 11 % with the addition of 0.07wt%La. While, the 0.14La added alloy exhibits comprehensive properties of tensile strength 600 MPa and electrical conductivity 80.08 %IACS after aging at 440 °C for 180 min. The increase in strength was primarily attributed to precipitation strengthening and dislocation strengthening. This work provides new kinds of Cu-1Cr-0.1Zr alloy and industrial suitable thermo-mechanical treatment for fabricating high performance cooper alloy sheets.

Comparison of academic achievement, graduation competency and academic sustainability of veterinary students based on college admission processes

A university’s admission policy is established to select applicants who can successfully complete the curriculum. Thus, it is important to develop optimal admissions processes for applicant selection. This study was conducted to infer the most suitable admission processes for veterinary school applicants by examining academic achievement, graduation competency and academic sustainability. It was conducted on students admitted from 2009 to 2018 at one of the veterinary colleges in Korea. The admission methods were divided into, first the regular admission (RA) process, primarily reflecting the results of the College Scholastic Ability Test, and second, the rolling admission processes. The rolling processes were further divided into admission officer-based (AO), high school grade point average-based (GA), essay test-based (ET), admission for the underprivileged (UP) and admission for overseas Koreans and foreigners (OKF). The final grade point average was observed to be higher in the order of the GA, AO and RA groups. The survey on the veterinary graduation competency did not reveal any difference between the regular and rolling admission processes. However, among the latter, AO-based admission showed a higher ratio of outstanding competency levels. In terms of academic sustainability, OKF admission demonstrated a higher rate of failure while RA showed a higher rate of expulsion and dropout. Summarizing the above results, the most successful veterinary applicants were selected through AO-based admission. These results are meaningful in providing the basic information required to establish admission policies for veterinary colleges in Korea.

Transmission and Dissipation of Vibration in a Dynamic Vibration Absorber-Roller System Based on Particle Damping Technology

The research of rolling mill vibration theory has always been a scientific problem in the field of rolling forming, which is very important to the quality of sheet metal and the stable operation of equipment. The essence of rolling mill vibration is the transfer of energy, which is generated from inside and outside. Based on particle damping technology, a dynamic vibration absorber (DVA) is proposed to control the vertical vibration of roll in the rolling process from the point of energy transfer and dissipation. A nonlinear vibration equation for the DVA-roller system is solved by the incremental harmonic balance method. Based on the obtained solutions, the effects of the basic parameters of the DVA on the properties of vibration transmission are investigated by using the power flow method, which provides theoretical guidance for the selection of the basic parameters of the DVA. Furthermore, the influence of the parameters of the particles on the overall dissipation of energy of the particle group is analyzed in a more systematic way, which provides a reference for the selection of the material and diameter and other parameters of the particles in the practical application of the DVA. The effect of particle parameters on roll amplitude inhibition is studied by experiments. The experimental results agree with the theoretical analysis, which proves the correctness of the theoretical analysis and the feasibility of the particle damping absorber. This research proposes a particle damping absorber to absorb and dissipate the energy transfer in rolling process, which provides a new idea for nonlinear dynamic analysis and stability control of rolling mills, and has important guiding significance for practical production.

Smartphone Usage Behavior And Technology Acceptance In Oil Palm Replanting

Replanting activities need support using information technology so that plantation business actors can access information related to plantations independently and accurately. This research analyzes smartphone usage behavior using a technology acceptance model approach among oil palm users. This research was conducted at the Karya Dharma III Village Unit Cooperative, Keranji Guguh Village, Koto Gasib District, Siak Regency. The sample taken in this research was 30 planters. The sampling technique in this research uses a snowball sampling technique, which is obtained through a rolling process based on the relationship between one respondent and another. Snowball sampling is a sampling method that uses initial illustration data to identify other illustrations that meet the criteria. Data analysis was carried out using a descriptive study based on a Likert scale. The final results of this research show that using smartphones among oil palm planters in Keranji Guguh Village as a medium to help search for and receive information for oil palm planters is classified as moderate, with an average score of 2.84. Smartphone use has become an alternative media planters use to search for information on supporting oil palm rejuvenation activities, land clearing, planting spacing patterns, using superior seeds, and plant maintenance replanting.