Bar Rolling Research Articles

Formation and Evolution Mechanism of the Inclusions of Al2O3·SiO2·CaO and Al2O3·SiO2·CaO·MgO in Seamless Steel Tube Steel

Herein, the formation and evolution mechanism of inclusions of Al2O3·SiO2·CaO and Al2O3·SiO2·CaO·MgO in seamless steel tube steel are investigated. In the long strip defects on the longitudinal cross section of the steel tube after the rolling bar piercing, the defect is mainly formed by Al2O3·SiO2·CaO·MgO inclusions and Al2O3·SiO2·CaO·inclusions dotted with·CaS inclusions after the rolling. The typical inclusions in the different steelmaking stages are mainly composed of CaS, Al2O3·(SiO2), CaO·(SiO2), MnS·(TiN), Al2O3·SiO2·CaO·(CaS)·(MnS), Al2O3·SiO2·CaO·MgO·(MnO), Al2O3·SiO2·CaO·MgO·(CaS)·(MnS), etc. In the billet, the average sizes of Al2O3·SiO2·CaO‐based and Al2O3·SiO2·CaO·MgO‐based inclusions are much larger than those of the other types of inclusions. Part of SiO2 in the deoxidized products SiO2 can be reduced by [Al], resulting in the formation of the Al2O3·SiO2 composite inclusions. The SiO2 in Al2O3·SiO2 inclusions can continuously be reduced by the dissolved [Ca] to form the Al2O3·SiO2·CaO composite inclusions. The SiO2 in the Al2O3·SiO2·CaO inclusions can be reduced by the dissolved [Mg] to form the Al2O3·SiO2·CaO·MgO composite inclusions. Another formation process of Al2O3·SiO2·CaO·MgO inclusions is the entrapment of ladle slag in the vacuum degassing (VD) stage, due to the strong agitation of the rising Ar bubbles in the vacuum condition of the VD stage.

Characteristics of Grade R4 Steel Manufactured by Ingot Casting and Used in the Production of Offshore Mooring Chains

The objective of this study is to characterise grade R4 steel manufactured by ingot casting that is used as the raw material for the production of offshore mooring chains. Rolled bars of grade R4 steel have been selected and metallographic analyses and micro hardness, tensile and Charpy V-notch impact tests performed. Tensile and Charpy V-notch impact tests have also been carried out on mooring links manufactured from the same grade R4 steel. Based on the results presented, the influence of the rolling reduction ratio of the bars and the influence of the ingot casting cooling and reheating process have been observed. Both factors have been found to increase product quality, particularly with respect to the central segregation and homogeneity of the rolled bars.

Development of simplified analytical model to predict the roll separating force in bar rolling

ABSTRACT Prediction of roll separating force (RSF) is necessary to design new rolling mills, optimise the number of passes and for online control of dimensional accuracy. The intricacy of deformation and complex mixed boundary conditions of velocity and friction makes exact analytical prediction of RSF in a bar or shape rolling quite difficult. Hence, the formula for the prediction of RSF while bar rolling is developed in this research using sticking and slipping friction, assuming the process is equivalent to compression of the simple rectangular bar between two flat plates. The concept of the weak plane strain is also incorporated in the proposed formula. Sinel’nikove’s formula derives the contact area between the roll and material. Considering the direct significance of the contact area on the value of RSF, the factors in the said formula are corrected based on a graphical method. Shida’s formula is used to calculate the flow stress. The proposed formula is compared with more than fifty distinct experimental findings found in the literature. It is found that the formula is in good agreement with majority of the experimental data. The derived simplified analytical formula can be successfully applied to most types of passes in such industries.

Reunderstand and Discuss the Hardness Limits of RCC-M M5110 Part Materials

RCC-M M5110 is the procurement code for rolling or forging bars for bolts and drive rods of class 1, 2 and 3 equipment of nuclear power plants. The individual high strength steels involved in this specification specify only the minimum hardness of the material and have no limit on the maximum hardness. The material selection of major components of nuclear power machinery equipment must meet the requirements of load bearing and safe operation, and ensure sufficient strength and hardness, which is especially important for the material selection of connecting bolts and driving rods of nuclear power equipment. As the strength and hardness of high strength steel increase, the plasticity and toughness of materials decrease sharply, as do the mechanical properties and corrosion resistance, increasing the risk of bolt fracture and equipment damage. In order to ensure the strength and hardness of metal materials, it is necessary to consider the comprehensive mechanical properties and corrosion resistance of the material, including resistance stress corrosion cracking (SCC). Improving strength and hardness should not be the only goal of improving the performance of metal materials. In the formulation and selection of raw material standards, the mechanical properties of important equipment materials, such as hardness, must be limited. To meet the requirements of "redundant design" and "defense in depth" of nuclear power equipment. This paper will discuss how to reunderstand the the hardness limits of RCC-M M 5110 materials.

Influence of the Grain-Flow Orientation after Hot Forging Process Evaluated through Rotational Flexing Fatigue Test

The hot forging process brings significant advantages in terms of improved mechanical properties of the part compared with other processes, such as casting or machining. The metal flow in the forging process leads to texture modifications and can be macroscopically visualized by the so-called grain-flow orientation (GFO). This study showed the effect of GFO on fatigue life by using a rotational flexing fatigue test. The tests that were performed using SAE 1045H steel material, at rolling and transverse directions, showed the influence of GFO on the specimens’ mechanical properties compared with the reference samples taken from the machined rolled bar. The experimental results showed that the forged samples with the GFO in the main deformation direction presented a higher fatigue life than the other tested configurations.

Innovative Methodology for Physical Modelling of Multi-Pass Wire Rod Rolling with the Use of a Variable Strain Scheme.

This paper presents the results of physical modelling of the process of multi-pass rolling of a wire rod with controlled, multi-stage cooling. The main goal of this study was to verify the possibility of using a torsion plastometer, which allows conducting tests on multi-sequence torsion, tensile, compression and in the so-called complex strain state to physically replicate the actual technological process. The advantage of the research methodology proposed in this paper in relation to work published so far, is its ability to replicate the entire deformation cycle while precisely preserving the temperature of the deformed material during individual stages of the reproduced technological process and its ability to quickly and accurately determine selected mechanical properties during a static tensile test. Changes in the most important parameters of the process (strain, strain rate, temperature, and yield stress) were analyzed for each variant. After physical modelling, the material was subjected to metallographic and hardness tests. Then, on the basis of mathematical models and using measurements of the average grain size, chemical composition, and hardness, the yield strength, ultimate tensile strength, and plasticity reserve were determined. The scope of the tests also included determining selected mechanical properties during a static tensile test. The obtained results were verified by comparing to results obtained under industrial conditions. The best variant was a variant consisting of physically replicating the rolling process in a bar rolling mill as multi-sequence non-free torsion; the rolling process in an NTM block (no twist mill) as non-free continuous torsion, with the total strain equal to the actual strain occurring at this stage of the technological process; and the rolling process in an RSM block (reducing and sizing mill) as tension, while maintaining the total strain value in this block. The differences between the most important mechanical parameters determined during a static tensile test of a wire rod under industrial conditions and the material after physical modelling were 1.5% for yield strength, approximately 6.1% for ultimate tensile strength, and approximately 4.1% for the relative reduction of the area in the fracture and plasticity reserve.

НЕСУЩАЯ СПОСОБНОСТЬ И ДЕФОРМАТИВНОСТЬ СВАРНЫХ ВЕРТИКАЛЬНЫХ СТЫКОВ КРУПНОПАНЕЛЬНЫХ ЗДАНИЙ НА ЗАКЛАДНЫХ ДЕТАЛЯХ

Analysis of the research results presented in the scientific and technical literature showed the absence of data about the operation of welded vertical joints of large-panel buildings on embedded parts with connecting elements in the form of bent and rolled angle bars. In order to determine the technical parameters necessary for the calculation and design of large-panel buildings, experimental researches of the operation of welded vertical joints on embedded parts with connecting elements in the form of bent and rolled corners under the action of tensile and shear forces were carried out. The static load was applied in stages until the destruction of the prototypes. During the experimental researches, the displacements in the place of bending of the connecting elements of the prototypes were recorded. On the basis of the experimental data obtained, the values of compliance of the connecting elements of the vertical joint on embedded parts were determined. Correction coefficients for the correct definition the compliance of connecting elements in the form of rolled and bent angle bars of a vertical joint on embedded parts are calculated and proposed. A different nature of deformation and destruction of welded vertical joints on embedded parts with connecting elements in the form of rolled and bent angle bars with the same geometric dimensions under the action of tensile and shear forces on the joints is revealed.

Modelling and Optimization of Process Parameters during Grooved Hot Rolling of SAE 1020 Steel

ABSTRACT The rolled SAE 1020 steel bars are widely used for production of mechanical components, such as, gears, spindles, camshafts, axles, fasteners, and gudgeon pins etc. Steel industries have been striving for productivity and better yield of hot rolled bar products. The roll separating force (RSF), driving torque (DT), end crop length (ECL), and drive energy (DE) are the important response parameters to be controlled for quality production, maximization of yield (i.e. 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, billet cross-section area, roll diameter, etc. This paper presents a study on the effect of the process parameters on the 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. The optimum rolling conditions for minimization of the response parameters have been obtained.

Design Method for Reinforced Concrete Based on Bond-Slip Energy Consumption

To reveal the energy consumption characteristics of a steel bar and all-lightweight shale ceramsite concrete (ALWSCC), focusing on hot rolled crescent ribbed bars (CRB) and hot rolled plain steel bars (PSB), a series of pull-out tests were carried out. The bonding failure modes, the contribution of the ribs to bond-slip failure and the energy consumption characteristics were analyzed based on the curves of pull-out load F-slip displacement S and energy consumption W–slip displacement S. Results show that the splitting failure is the main failure of the CRB specimen, and the pulling out failure is the main failure of the PSB one. The ratio of the total energy dissipation of splitting failure to that of the pulling out failure is less than 30%. The mechanical bite force between CRB and concrete contributes more than 95% to the bond strength. The pull-out force is divided into four stages, such as the chemical adhesive force stage (elastic and micro-elastic strain stage), the common-effect stage of mechanical bearing force and static frictional force (plastic development stage), and the frictional force stage (crushed stage). The new design is proposed to guarantee the ductility of the reinforced concrete structure, which is based on the bond-slip energy consumption rather than the traditional strength design. The conclusions provide a reference to the reinforced concrete practice.

Self-reported Quad Bike Use, Safety Behaviors, and Safety Awareness among Young Adults in U.S. and Canadian Agriculture

ABSTRACT The number of agricultural fatalities and injuries related to agricultural quad bike use has risen substantially in the last two decades. Safe engineering design features such as crush protection and roll bars have proven potential to lessen the burden of injury but have traditionally not been included in many quad bike safety training programs. The aim of this study was to survey more than 700 young adults working in U.S. and Canadian agriculture to examine self-reported quad bike safety behaviors and awareness of quad bike safety design engineering features. We found that U.S. males continue to be at higher risk for quad bike-rollover incidents when compared to other groups. Even when accounting for other factors such as age and country, we found that participants who reported youth occupational quad bike use (≤14 years old) were up to 200% more likely to allow extra riders and up to 489% more likely to not wear a helmet when compared to participants who reported beginning occupational quad bike use in adulthood. These findings support the Agricultural Youth Work Guideline (AYWG) for occupational quad bike use at age 16. Less than 20% of young adults working in agriculture were aware of safe design features such as wide frames, stability ratings, crush protection devices, and accessories made by the original equipment manufacturer. There is tremendous need to educate the future agricultural workforce about the importance of choosing quad bikes with safer design features.

Large (Ti, V) Carbonitride in Nonquenched and Tempered Steel 38MnVS6

Large (Ti, V) carbonitrides with size even up to tens of microns in autoparts steel 38MnVS6 are studied in this work. A great number of micron-sized (Ti, V) carbonitrides are found in continuous casting billet, and the atomic ratios of V/Ti are mainly distributed in range 0.130–0.200 with an average value of 0.171. The large (Ti, V) carbonitrides have irregular morphologies, and some even have an obviously extending shape along the dendrite boundary. 3D morphologies of the large (Ti, V) carbonitride after being etched by AA solution present obvious long and flake shapes. The large (Ti, V) carbonitride has high thermal stability even at 1200°C, even though the atomic ratio of V/Ti has a decreasing tendency. There are still many large (Ti, V) carbonitrides in the rolled bar and partially broken in some which are clearly visible. According to the Thermo-Calc calculation result, the large (Ti, V) carbonitride precipitates in liquid steel during solidification. The chemical compositional characteristic is the result of subsequent mutual diffusion of elements Ti, V, C, and N. Simply reducing the content of Ti, even 13 ppm cannot eliminate the large (Ti, V) carbonitride for the nitrogen-containing, nonquenched, and tempered steel, but the quantity and size of large carbonitride are significantly reduced.

Correlations between processing technology, microstructure and properties of a Ni-rich Ti–Ni shape memory alloy

A Ti-50.8Ni (at.%)/Ti-55.9Ni (wt.%) VIM processed ingot was rotary swaged and rolled in parallel, obtaining bars with a total Area Reduction above 90% (from forged/rolled raw state one). Throughout the successive stages, the microstructural evolution, thermal and mechanical properties were compared. Deformation bands, grain morphology, precipitates and oxidation were evaluated (by OM and SEM/EDS). An essentially (∼100%) austenitic phase was detected at room temperature (via XRD/Rietveld method), while the Martensitic Transformation temperatures occurred at negative temperatures (via DSC). The rolled bar got through the process more regularly, with homogeneous and refined structure. Typical defects such as superficial microcracks and creases were relevant in the last stages of the two-dies rotary swaging with inductive heating. The work hardening level (via Hardness Test) was similar in both metal forming processes, being 5–7% more pronounced at the edge area of the bars due to redundant work.

Modeling of Tensile Test Results for Low Alloy Steels by Linear Regression and Genetic Programming Taking into Account the Non-Metallic Inclusions

Štore Steel Ltd. is one of the biggest flat spring steel producers in Europe. The main motive for this study was to study the influences of non-metallic inclusions on mechanical properties obtained by tensile testing. From January 2016 to December 2021, all available tensile strength data (472 cases–472 test pieces) of 17 low alloy steel grades, which were ordered and used by the final user in rolled condition, were gathered. Based on the geometry of rolled bars, selected chemical composition, and average size of worst fields non-metallic inclusions (sulfur, silicate, aluminium and globular oxides), determined based on ASTM E45, several models for tensile strength, yield strength, percentage elongation, and percentage reduction area were obtained using linear regression and genetic programming. Based on modeling results in the period from January 2022 to April 2022, five successively cast batches of 30MnVS6 were produced with a statistically significant reduction of content of silicon (t-test, p < 0.05). The content of silicate type of inclusions, yield, and tensile strength also changed statistically significantly (t-test, p < 0.05). The average yield and tensile strength increased from 458.5 MPa to 525.4 MPa and from 672.7 MPa to 754.0 MPa, respectively. It is necessary to emphasize that there were no statistically significant changes in other monitored parameters.

Effect of Heat Treatment Before and After Incremental Rolling on the Mechanical Properties of Titanium-Stabilized Austenitic Stainless Steel

Austenitic stainless steel 08Ch18N10T stabilised with titanium is used for parts of VVER nuclear power reactors. The final mechanical properties are strongly affected by the previous processing history. This is mainly due to the deformation hardening that is incorporated into the material during the production of semi-finished products. The experimental program was performed on 08Ch18N10T steel bars with a diameter of 30 mm. Incremental rolling was performed on bars that remained in the delivered condition and on bars subjected to solution annealing at 1020 °C for 60 minutes before rolling. The rolled bars were stabilised annealed at different temperatures. Then a metallographic evaluation and a tensile test at RT and 350 °C were performed. The results show that the rolling speed significantly affects the mechanical properties after stabilisation annealing. By reducing the rolling speed, it was possible in some cases to increase the yield strength up to 349 MPa. The stabilisation annealing temperature of 720 ° C with a holding time of 10 hours was evaluated as the most advantageous. In the case of higher stabilisation annealing temperatures, the lowest rolling speed, i.e. 25 rpm, had to be performed to achieve higher hot yield strength values exceeding 177 MPa.

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.

Numerical Simulation of Microstructure Evolution of Large GCr15 Bar during Multi-Pass Rough Rolling

Severe temperature gradients and inhomogeneous strain distribution exist in the large cross-section of GCr15 bearing steel during the hot bar rolling process, resulting in a complex microstructure evolution in the bar. To promote the performance of the bar, a thermal-mechanical coupled finite element (FE) model was developed to capture the variations in temperature and deformation strain. A subroutine, considering the dynamic recrystallization (DRX), meta-dynamic recrystallization (MDRX), static recrystallization (SRX), and grain growth (GG) of austenite grains of GCr15 steel, was developed and coupled to the FE model to predict the microstructure’s evolution during rough rolling. The simulation implies that the inner part of the bloom is deformed at high temperatures due to the heat generated by plastic deformation and slow heat conduction, while the surface temperature decreases along with the passes. The heavy reduction design with 11 passes was found to introduce higher strains at the center regions than those of the same rough rolling reduction divided into 13 passes. The higher strains at the center regions refined the grain size and promoted microstructure homogeneity. The observation of the microstructures after hot bar rolling confirmed the refinement of the heavy reduction design for rough rolling. Furthermore, the heavy rough rolling reduction was found to be beneficial for alleviating the macrosegregation of the casting bloom.

Validation of a new system for measuring material constants representing damage limits

This paper describes a test for the determination of damage function limits. The proposed test consists of skew rolling of conical specimens. The test is carried out under real conditions to determine the crack initiation point, and then it is modelled numerically to determine the limit values of the damage function at the determined crack initiation point. This paper presents a methodology for the determination of limit values of the damage function on the example of C45 steel at three different temperatures, i.e. 950 °C, 1050 °C and 1150 °C. The research was carried out using the Oyane criterion as an example. The limit value of the damage function at 1000 °C was determined by regression using the calculated damage function values. The value of the damage function was adapted to a numerical model of a skew-rolling process of a bar with the deletion of elements, which took place when the limit value of the damage function determined in the test was exceeded. The numerically simulated skew rolling case was also realised in real conditions. Based on the results obtained from the skew rolling of bars, a quantitative and qualitative validation of the new damage function limit test was carried out.

Microstructure Study on Large-Sized Ti–6Al–4V Bar Three-High Skew Rolling Based on Cellular Automaton Model

The large diameter titanium alloy bars are usually manufactured by forging, which leads to large metal loss, high cost, low efficiency and limited product specifications. This paper adopted three-high skew rolling technology to roll Ti–6Al–4V bar with the diameter of 300 mm. With the reduction of 50 mm, the three-roll skew rolling model was developed by DEFORM-3D finite element software. A cellular automatic model (CA model) of large-sized titanium alloy bar cross-rolled was established, considering the effects of dislocation, recovery and nucleation on dynamic recrystallization. The microstructure evolution process is effectively simulated. During the process of rolling, dynamic recrystallization occurs in the outer layer of the rolled piece at first. The new nucleations form at the grain boundary, then grow into their secondary phase. With the rolling proceeding, the dynamic recrystallization gradually extends to the core of bar. The microstructure of the rolled bar is uniform and the grain size is refined with the average grain size of approximately 10 μm. The simulation results are compared with the experimental results, the actual grain size is a little coarser than that obtained by the CA model. Some reasons are given to reasonably explain the phenomenon.

Tailored Fully Lamellar Microstructure of a Newly Developed Mn-Containing β-Solidifying γ-TiAl Alloys Rolled Bar

Tailored Fully Lamellar Microstructure of a Newly Developed Mn-Containing β-Solidifying γ-TiAl Alloys Rolled Bar