Hot-rolled Material Research Articles

Investigation of CuTi Alloy for Applications as Non-Sparking Material

A new non-sparking metallic material, Cu-Ti, with applications in potentially explosive environments is proposed as an alternative to CuBe, to reduce the processing and toxic effects of Be. Using high-purity Cu and Ti materials, a Cu (~3–4 wt%) Ti alloy with good chemical and structural homogeneity was fabricated in an induction furnace under an Ar atmosphere. The hot-rolled material was tested in an explosive gas mixture (10% H2 or 6.5% CH4) under extremely severe wear tests for 15,000 cycles, and no hot sparks were produced to ignite the medium. The material was investigated as hot-rolled plates (600 s at 950 °C and 10% reduction). The microstructures and surface of the wear test samples were investigated by light optical microscopy (LOM) and scanning electron microscopy (SEM). The chemical compositions were determined by energy dispersive spectrometry (EDS). The corrosion behavior was studied using electrochemical techniques: open-circuit, linear, and cyclic potentiometry in saline electrolyte solutions. The mechanical properties, such as microhardness and friction coefficient, were determined using UMT equipment. The results showed that the alloy is suitable for applications requiring non-ignition properties, with good hot rolling deformability and chemical composition homogeneity. Regarding the corrosion analysis and mechanical properties of the experimental CuTi alloy, minor differences were observed between the cast- and hot-rolled material.

Electropolishing study of metastable austenitic steel AISI 347 for EBSD analyses

Abstract For the metastable austenitic steel AISI 347 (X6CrNiNb18-10), various electropolishing parameters were evaluated by means of hardness testing, electron backscatter diffraction (EBSD), and atomic force microscopy. Depending on the chosen parameters, different surface characteristics could be achieved simply by only varying voltage, flow rate, and polishing time, although EBSD indexing was always possible. Differences in hardness of up to 20 HV0.5 and in microscopic roughness could be detected on otherwise comparable samples. Finally, the microstructure distribution of a hot rolled bar material with a diameter of 153 mm made from AISI 347 was characterized over the cross section using the previously determined parameter set. Here, insights about recrystallization during forming were concluded and δ-ferrite was differentiated from α’-martensite by kernel average misorientation and morphology.

Mechanical Properties and Wear Resistance of Biodegradable ZnMgY Alloy

Biodegradable metallic materials are gaining attention for medical applications in short-term implants (15–500 days) because of their good mechanical properties, biocompatibility, and generalized corrosion. Most medical applications involve implant wear processes, particularly for bone fractures. Parallelepipedic specimens (dimensions 50 mm × 10 mm × 3 mm) were obtained by cutting the hot-rolled material processed from cast ingots of ZnMgY. To test the tribological performance of these stationary specimens, they were placed at the upper point of the machine’s tribological contact. The rotating lower disk of the AMSLER machine (AMSLER & Co., Schaffhouse, Switzerland) is manufactured from AISI 52100 bearing steel with a 62–65 HRC hardness and a diameter of 59 mm both radially and axially. Frictional torque is the parameter that is measured. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to analyze the worn areas. The material behavior in the normal and wear states upon immersion in simulated body fluid (SBF) was evaluated.

Integrated Assessment of MIG Welding Parameters on Carbon Steel using RSM Optimisation

This study examined how parameter optimisation in MIG welding affects material properties, weld quality, flexural strength, and weld bead geometry using an experimental design. Structural testing reveals that weld pool imperfections, especially in welded joints, often lead to metal failure. Incorrect selection of welding parameters, material weldability, and metal forming contribute to defects and necessitate post-treatment. The study aims to minimize weld defects and maximize material strength in welded parts using a quadratic second-order regression model to predict optimal process parameters. The chosen JIS G3131 hot-rolled carbon steel material is commonly used in automotive parts, is cost-effective, and can be easily welded. The welding process is MIG buttweld according to AWS 1.1 standards. The tests match the RSM design's 3-by-3 orthogonal array. The process parameters are welding current, arc voltage, and welding speed. The responses are bead height, bead width, penetration, and flexural strength. NDT X-ray radiography detects flaws in weld pools. The welded connection's durability is determined with a three-point bending test. Experiments are conducted to find the best input parameters with 95% confidence. This study also uses an experimental design based on an orthogonal array and an analysis of variance (ANOVA). Contribution to factors and regression analysis. The predicted flexural strength was 903.1 MPa, with a 0.66% error compared to the experimental value of 897 MPa. Predicted values for weld penetration, bead width, and bead height are 3.01, 9.45, and 2.04. In the RT inspection test, the test sample with the optimum parameters had no defects in the welded joint. The optimal parameter values for the regression analysis of the RSM combination are 115, 20, and 18 for current, speed, and voltage. Confirmation tests for DT and NDT were performed to validate the optimal parameter settings. This research shows that optimizing process parameters for welded products improves weld geometry and flexural strength. This method is widely used and valuable in metal fabrication.

An optimized energy efficient design of a light gauge steel building

This paper presents a case study of an energy efficient and cost optimized design of a light gauge steel building. The structural analyses conducted were linked to the concept of design for manufacture and assembly (DfMA) for the optimization of assembly time, quantity of labors and materials. A variety of analyses were performed on a prefabricated residential building constructed with cold formed and hot rolled steel materials for comparison which has a limited research previously. The energy optimization for the prefabricated building was carried out using Autodesk Insight 360. Several tools for structural, thermal, energy and cost analyses were adopted in this research. A Building Information Model (BIM) was developed in Revit and structural model in ETABS for structural analysis. Thermal performance was executed using Simulinks in MATLAB followed by energy simulations in DesignBuilder and EnergyPlus software packages. The material and energy costs of the designed building were estimated using CostX tool. From the analysis, the optimal window-wall ratio (WWR) was found to be 10%− 15% produced better energy and cost savings. Furthermore, the total energy consumption and greenhouse gas emissions of the building was found to be reduced by 28.7%− 31.5% with an application of insulation in its external walls in simulations. Improved bending capacity and shear force for CFS compared to RHS was observed. Finally, a framework was proposed for the automation and interoperability of building analysis tools.

VHCF of the 3D-Printed Aluminum Alloy AlSi10Mg

The paper is focused on the very high cycle fatigue (VHCF) properties of aluminum alloys proceeded in two different technological procedures. The hot-rolled D16T alloy is compared with the selected laser melting (SLM) AlSi10Mg alloy. The fatigue tests were performed at a high frequency (20 kHz) in the laboratory air environment at room temperature. The experimental results showed a significant difference in fatigue strength between hot-rolled and SLM materials. The VHCF properties of AlSi10Mg were more than two times lower than those of D16T in spite of the comparable quasi-static tensile properties. The difference in fatigue properties was explained based on fractographic analysis of fracture surfaces. The morphology of the fracture pattern was qualitatively different. In the case of the hot-rolled alloy, the three clear zones of crack growth could be outlined. The main part of the pattern was covered by quasi-brittle facets that are typical for VHCF fractures in Al alloys. In the case of the SLM material, unregulated structures were found in the microstructure. In some local zones, numerous non-melted particles were observed on the fracture surface. The boundaries of certain layers also played an important role in the fracture. Large, separated surfaces were observed on the fracture pattern. It is important to note that these boundaries were not associated with the layer-by-layer building of the specimen. The distance between such features was significantly larger than the thickness of an individual layer.

Analysis of the mechanism of chromatic aberration defects on A510L surface of high quality hot rolled pickled strip

In view of the chromatic aberration defects on the surface of hot-rolled strip A510L after pickling, the microscopic morphology features of different positions of the pickled strip surface were compared and analyzed by using laser confocal microscope (CLSM), and the generation mechanism of chromatic aberration defect was studied by using high-resolution scanning electron microscope and energy dispersive spectrometer (EDS). The results show that the main cause of surface chromatic aberration defects on the surface of pickling plate A510L is closely related to the interface state between hot-rolled raw material substrate and iron oxide scale, and there is an enrichment area of Fe2SiO4/FeO binary eutectic near the hot-rolled raw material substrate and iron oxide scale, and the proportion of Fe2SiO4 is higher as it approaches the strip steel matrix, and Fe2SiO4/FeO has a strong pinning effect, which leads to the adhesion of iron oxide scale. The existence of Fe2SiO4/FeO changes the structure of carbon steel iron oxide scale, which makes the bonding force between iron oxide scale and strip steel matrix increase the difficulty of pickling process, and finally presents the surface chromatic aberration defects after pickling.

An alternative quenching and partitioning (Q&P) process via spheroidization

A hot-rolled Fe-CMnSiMo alloy was subjected to quenching followed by a spheroidization treatment, which resulted in a microstructure consisting of Mn enriched cementite particles dispersed in the ferrite matrix. The as hot-rolled and spheroidized material was subjected to short-duration intercritical annealing (IA) treatment followed by the full quenching and Q&P treatments. The IA treatment was such that the austenite formed as a result of dissolution of cementite particles retains its higher Mn content. The influence of this chemical inhomogeneity on martensite transformation and retained austenite stability was investigated using a dilatometer and interrupted compression experiments, respectively. The results were compared with the microstructure obtained in the absence of chemical heterogeneity by subjecting the hot-rolled material to similar heat treatment directly without the quenching and spheroidization treatment. After the IA treatment, the Ms temperature of the spheroidized material was 36 °C higher than the Ms temperature of the as hot-rolled material. Nevertheless, a higher fraction of retained austenite was stabilized in the spheroidized material after the IA treatment followed by full quenching. The SEM, TEM and DICTRA modelling results showed that cementite particles dissolve during the IA treatment of the spheroidized material and the product austenite retains its higher Mn content. Interrupted compression test results show that the retained austenite in the spheroidized material has greater stability because of its higher Mn content and small size.

Fatigue performance and acoustic emission behavior of remanufactured low-carbon steel made by wire and arc additive manufacturing

The fatigue behavior of low-carbon steel made by wire and arc additive manufacturing (WAAM) is studied. The role of the microstructures underpins the difference in fatigue performance between WAAM and hot-rolled materials is investigated using scanning electron microscopy (SEM), optical metallography, and in-situ acoustic emission. Results show the WAAM low-carbon steel has a lower fatigue crack growth rate (FCGR) comparing with the hot-rolled steel. The mechanisms enhancing the fatigue performance are a lower volume fraction of pearlite and the interlocking basket weave microstructure in WAAM specimens. The anisotropy in the FCGR of WAAM low-carbon steel is very small.

Measurement of the Anisotropic Dynamic Elastic Constants of Additive Manufactured and Wrought Ti6Al4V Alloys.

Additively manufactured (AM) materials and hot rolled materials are typically orthotropic, and exhibit anisotropic elastic properties. This paper elucidates the anisotropic elastic properties (Young’s modulus, shear modulus, and Poisson’s ratio) of Ti6Al4V alloy in four different conditions: three AM (by selective laser melting, SLM, electron beam melting, EBM, and directed energy deposition, DED, processes) and one wrought alloy (for comparison). A specially designed polygon sample allowed measurement of 12 sound wave velocities (SWVs), employing the dynamic pulse-echo ultrasonic technique. In conjunction with the measured density values, these SWVs enabled deriving of the tensor of elastic constants (Cij) and the three-dimensional (3D) Young’s moduli maps. Electron backscatter diffraction (EBSD) and micro-computed tomography (μCT) were employed to characterize the grain size and orientation as well as porosity and other defects which could explain the difference in the measured elastic constants of the four materials. All three types of AM materials showed only minor anisotropy. The wrought (hot rolled) alloy exhibited the highest density, virtually pore-free μCT images, and the highest ultrasonic anisotropy and polarity behavior. EBSD analysis revealed that a thin β-phase layer that formed along the elongated grain boundaries caused the ultrasonic polarity behavior. The finding that the elastic properties depend on the manufacturing process and on the angle relative to either the rolling direction or the AM build direction should be taken into account in the design of products. The data reported herein is valuable for materials selection and finite element analyses in mechanical design. The pulse-echo measurement procedure employed in this study may be further adapted and used for quality control of AM materials and parts.

Phase Separation in Super Duplex Stainless Steel at 300 °C - Comparing Hot-Rolled Base Material and Tig Welds

Phase Separation in Super Duplex Stainless Steel at 300 °C - Comparing Hot-Rolled Base Material and Tig Welds

A modified Paris Law approach to fatigue crack propagation in cold drawn pearlitic steel

This scientific article offers an innovative approach to fatigue crack growth in progressively cold drawn pearlitic steels that exhibit a microstructurally-induced tortuous propagation path (zig-zag fatigue crack path). The proposed novel approach, Toribio-González-Matos (TGM) model, consists of a modified Paris Law including the real fatigue crack growth length (i.e., the locally multiaxial, microstructurally tortuous, fatigue crack growth distance) instead of the apparent fatigue crack growth length (i.e., the globally uniaxial, fatigue crack propagation distance, projected in the direction of global fatigue propagation in mode I). Whereas the conventional Paris Law considers the apparent projected distance (straight line), the approach introduced here (i.e., the TGM model) proposes the consideration of the real, non-projected, tortuous, microstructurally-induced fatigue crack growth length with zig-zag shape (longer that the conventionally projected in global mode I). It is seen that the fatigue crack propagation real distance (longer) when compared to the fatigue crack propagation projected distance (shorter) is the reason for the better fatigue performance of heavily cold drawn pearlitic steels in relation to the performance of the original hot rolled material before cold drawing, due to the increase of microscopically-induced crack deflection angle in the heavily cold drawn material.

Effect of Internal Structure of Nozzle on Impingement Heat Transfer Performance of Single-beam Water Jet

Ultra-fast cooling (UFC) equipment is an important means to produce high-quality hot-rolled steel materials. Nozzle is the key component of the UFC equipment, which has great influence on the cooling performance. In this paper, the influence of internal structure of the nozzle on the heat transfer performance of water jet impingement was studied experimentally, so as to obtain an excellent nozzle structure. Under the same inlet pressure and outlet flow of the nozzle, heat transfer experiments were carried out on a 750°C stainless steel plate. During the experiment, the actual flows of the nozzles and the temperatures inside the steel plate were recorded. Flow coefficients of the nozzles, surface temperatures and surface heat flux of the steel plate were calculated. Experimental results showed that the flow coefficient of the 30° nozzle was the largest, followed by the 13.4° nozzle, and then the 45° nozzle. It could be found that, under the same inlet pressure, heat transfer performance was positively related to the flow coefficient of the nozzle. Moreover, under the same outlet flow, the heat transfer performance of each nozzle was very similar. Overall, the heat transfer performance of the 30° nozzle was excellent and recommended to be used preferentially in the UFC equipment.

Effect of repeated warm rolling cold rolling and annealing on the microstructure and mechanical properties of AISI 301LN grade austenitic stainless steel

Global warming now days is an important issue over the world. To reduce the effect of global warming high strength structural steels are required to develop which will able to make safe body white future vehicle. In this matter advanced thermomechanical treatments of steel play a vital role. In present context, a repeated warm rolling, cold rolling and annealing treatments were applied to AISI 301LN grade austenitic stainless steel. Due to formation of ultra-fine grain structure (Average grain size ≈ 4 µm) at treated materials as compared to large grain (Average grain size ≈ 35 µm) structure of as-received material, the treated steel was showing excellent mechanical properties. It was showing 667 MPa Y.S., 1095 MPa U.T.S. and 40% elongation as compared to 405 MPa Y.S., 841 MPa U.T.S. and 78% elongation of base material. The average misorientation angle of the treated specimen was slight high (≈ 390) in compare with as received hot rolled material (≈ 340). This is the indications of highly recrystallized structure of the treated materials. It indirectly helps to improve the mobility of dislocations around grain boundary towards improvement of the ductility of the material. The fractographic image of the treated material is supporting the high ductile behavior along with high strength of this material.

Residual stress states in cementite and ferrite in a combined cold drawing process of AISI 1045 steel using neutron diffraction and synchrotron radiation

The evaluation and control of residual stress states in manufacturing processes such as cold drawing can be difficult, especially in multi-phase materials. Diffraction methods are ideal for characterizing residual stresses in individual phases provided these phases scatter neutrons or X-rays well enough to obtain a good signal. Residual stresses determination problems in drawn components have been reported. Main constraints are measurements in the primary ferrite phase only. The presence of cementite in carbon steel is often neglected. A problem that has not yet been extensively investigated is how residual stresses in the ferrite and cementite phases develop in subsequent steps of material processing such as cold drawing. In this work a combined straightening and bar drawing process of AISI 1045 round bars from coils of a hot-rolled material was investigated. A careful characterization of the material, including residual stress states in the ferrite (α−Fe) and cementite (Fe3 C) phases, using neutron diffraction and synchrotron diffraction was performed for each of the different manufacturing steps. The drawing and polishing and straightening (P.S.) parameters by crossed rolls were changed to evaluate their influence on the α−Fe and Fe3 C residual stress distributions. After the drawing process, residual stresses in the cementite phase are highly tensile, as already reported, however it can be shown that after polishing and straightening steps residual stresses in the cementite phase decrease and residual stress distributions also depend on the tool angle used.

하이브리드 프로토타입 듀얼 로드 셀 구조 개발

We have developed the hybrid prototype load cell structures. These developed load cell structures may increase the reliability of the load sensing by deriving the load values through the double sensing method through the vertical maximum deflection and bending stress of the simple beams. For this purpose, the structure design was performed so that the load value, the deflection and stress value could be output to the same value through the optimal structure design. The structurally designed dimensions reaffirmed the accuracy of the design through the structural analysis program and the matching of the load value and the deflection value. Based on the designed structural dimension, the prototype form was constructed through laser cutting and production using hot rolled steel materials. The developed prototype load cell structure can be used as good educational material in various subjects such as material mechanics, steel structure design, measurement engineering, and mechatronics engineering. It is also believed that the measurement system ideas can inform the occurrence of errors in the event of a problem, and if a major accident caused by a sensing error is predicted, it will show good utilization to prevent accidents.

Surface Nanostructuring of a CuAlBe Shape Memory Alloy Produces a 10.3 ± 0.6 GPa Nanohardness Martensite Microstructure.

Severe plastic deformation (SPD) has led to the discovery of ever stronger materials, either by bulk modification or by surface deformation under sliding contact. These processes increase the strength of an alloy through the transformation of the deformation substructure into submicrometric grains or twins. Here, surface SPD was induced by plastic deformation under frictional contact with a spherical tool in a hot rolled CuAlBe-shape memory alloy. This created a microstructure consisting of a few course martensite variants and ultrafine intersecting bands of secondary martensite and/or austenite, increasing the nanohardness of hot-rolled material from 2.6 to 10.3 GPa. In as-cast material the increase was from 2.4 to 5 GPa. The friction coefficient and surface damage were significantly higher in the hot rolled condition. Metallographic evidence showed that hot rolling was not followed by recrystallisation. This means that a remaining dislocation substructure can lock the martensite and impedes back-transformation to austenite. In the as-cast material, a very fine but softer austenite microstructure was found. The observed difference in properties provides an opportunity to fine-tune the process either for optimal wear resistance or for maximum surface hardness. The modified hot-rolled material possesses the highest hardness obtained to date in nanostructured non-ferrous alloys.

Applicability of Hybrid Built-Up Wide Flange Steel Beams

To accommodate growing demands on either heavy steel structures or unique buildings with irregular configurations, built-up wide-flange steel (BWS) beams are being popularly used in modern steel construction. In current fabrication practices of BWS members, high-performance steels produced in steelmaking factories under the thermo-mechanical control process (TMCP) are typically utilized to achieve proper welding performances. However, since its basic unit price is quite higher than typical hot-rolled steel materials, this study introduced a hybrid BWS section for cost saving with no performance degradation, where high-performance TMCP steel was used in flanges, and conventional hot-rolled steel was adopted in web plate. To verify the tensile performances of a hybrid BWS section with non-uniform properties, split T tension and Charpy impact tests were conducted, and flexural tests were also carried out on hybrid and homogeneous BWS beam members. On this basis, it was confirmed that the structural performance of the hybrid BWS member is comparable with that of the conventional one with a uniform section property.

Influence of cold and hot rolling on the corrosion behaviour of duplex stainless steels in mine water environment

This study examined the corrosion behaviour of cold and hot rolled duplex stainless steel materials in mine water. Both gravimetric and electrochemical methods (potentiodynamic polarisation and open circuit potential) were adopted to monitor the corrosion of the alloys. Microscopy analyses were used to understand the degradation phenomena. In comparison, cold-rolled stainless steels displayed better resistance than hot-rolled materials under the tested conditions. The mine water pH was in the range that could lead to passivation of the sample and hence, the environmental impact was not aggressive enough to create many inferences. The surface deteriorations for cold and hot rolled steel materials were therefore not severe in both SEM (Scanning Electron Microscope) and OM (Optical Microscope) analysis results.

The Effect of Hot Working on the Mechanical Properties of High Strength Biomedical Ti-Nb-Ta-Zr-O Alloy.

Beta titanium alloy Ti-35Nb-6Ta-7Zr-0.7O (wt%) was developed as a material intended for the manufacturing of a stem of a hip joint replacement. This alloy contains only biocompatible elements and possesses a very high yield strength already in the cast condition (900 MPa). However, the porosity, large grain size and chemical inhomogeneity reduce the fatigue performance below the limits required for utilization in the desired application. Two methods of hot working, die forging and hot rolling, were used for processing of this alloy. Microstructural evolution, tensile properties and fatigue performance of the hot worked material were investigated and compared to the cast material. Microstructural observations revealed that porosity is removed in all hot-worked conditions and the grain size is significantly reduced when the area reduction exceeds 70%. Static tensile properties were improved by both processing methods and ultimate tensile strength (UTS) of 1200 MPa was achieved. Fatigue results were more reproducible in the hot rolled material due to better microstructural homogeneity, but forging leads to an improved fatigue performance. Fatigue limit of 400 MPa was achieved in the die-forged condition after 70% of area reduction and in the hot rolled condition after 86% of area reduction.