Finishing Of Steel Research Articles

Development and experimental investigation of magnetic abrasive finishing of 17-4PH steel

Magnetic abrasive finishing (MAF) is a promising process for achieving better surface finish, not only on softer materials, but also on harder materials. In several industries, 17-4PH steel has predominantly being used due to its exceptional properties of better corrosion resistance, high strength-to-weight ratio, and ease of weldability. In this article, the details of a developed MAF attachment for a CNC vertical milling machine are presented. The developed attachment was used to finish the surface of 17-4PH steel and is suitable for plane workpiece surface. Effect of various MAF process parameters such as rotational speed of electromagnet, supply voltage/current, abrasive mesh number, and working gap were studied on 17-4PH steel for material removal rate (MRR) and percentage change in surface roughness (PCSR) using one-factor) using one-factor-at-a-time approach (OFAT). Based on experimental results, on increasing voltage/current, increase in MRR and PCSR was observed; however, decrease in PCSR and MRR was noticed with increase in the working gap. PCSR was increased up to 600 rpm of electromagnet and 600 mesh number. However, on further increase in speed and mesh number, resulted in decrease in PCSR. Supply voltage/current was the most significant input process parameter on PCSR for the constant values of others parameters. Maximum PCSR of 90.37% was observed at 1.5 mm working gap, 600 rpm rotational speed, 600 mesh number and 24 V/0.9A voltage/current. The results reported in the article are useful in identifying the relative significance of parameters for the selected workpiece material.

Effect of Aluminium Oxide with Boron Nitride Grinding Wheel on Surface Roughness with Finishing of EN-8 Steel

This paper focuses on the effect of internal grinding process using a grinding wheel on the surface roughness aspect of ductile material. The surface roughness depends on various machining parameters which are feed rate, cutting speed, material removal rate and depth of cut. As varying the different machining parameters in internal grinding process, small internal grinding wheel made out of aluminium oxide-Al2O3 with boron nitride and adhesive type i.e., vitrified bond has been used for this study. Additionally, coolant also constitutes a major role to improve surface roughness, material removal rate and the wheel life. The roughness value was measured by using Mitutoyo portable roughness tester code: 178-561-02E surf test-SJ-210. Comparatively, it could be deduced that the wheel using Al2O3 with boron nitride has a better surface roughness in comparison with Al2O3 grinding wheel intern increases the wheel life.

Effects of Surface Roughness on Shock-Wave/Turbulent Boundary-Layer Interaction at Mach 4 over a Hollow Cylinder Flare Model

Although it is understood that surface roughness can impact boundary layer physics in high-speed flows, there has been little research aimed at understanding the potential impact of surface roughness on high-speed shock-wave/boundary-layer interactions. Here, a hollow cylinder flare model was used to study the potential impact of distributed surface roughness on shock-wave/boundary-layer interaction unsteadiness. Two surface conditions were tested—a smooth steel finish with an average roughness of 0.85 μm and a rough surface (3K carbon fiber) with an average roughness value of 9.22 μm. The separation shock foot from the shock-wave/boundary-layer interaction on the hollow cylinder flare was tracked by analyzing schlieren images with a shock tracking algorithm. The rough surface increased boundary layer thickness by approximately a factor of 10 compared to the smooth case, significantly altering the interaction scaling. Despite normalizing results, based on this boundary layer scaling, the rough surface case still exhibited mean shock foot positions further upstream more than the smooth surface case. Power spectra of the unsteady shock foot location data demonstrated that the rough surface case exhibited unsteady motion with attenuated energy relative to the smooth-wall case.

Experimental investigation of a novel magnetorheological process based on three revolving curved tip tools for finishing of mild steel

High-quality surface of the cylindrical workpieces would have to be very precise when used in automobile industries, vane pumps, turbines, gears, mild steel dies and punches for plastic industries. The magnetorheological finishing process based on three revolving curved tip tools has been developed for external cylindrical components to address the above issues. Three electromagnetics tools have been used in this magnetorheological method that can move radially inwards or outwards according to the external diameter of the workpiece. During finishing, the workpiece rotates in the anti-clockwise direction, and three curved tip tools revolve around the workpiece in a clockwise direction resulting in more interaction between the workpiece and active abrasive particles. Reciprocating movement is also provided to the workpiece that helps to produce the axial force on the active abrasive particles. The proposed method has been applied to a mild steel shaft to investigate the surface finish of its external surface. Response surface methodology (RSM) has been used to plan and analyse the impacts of different process factors on the percentage change in surface roughness value of the finished surface of the mild steel stepped cylindrical shaft. The optimal combination of process parameters is magnetising current 3.4A, revolving speed of tools 26 rpm, the rotational speed of workpiece 440 rpm, and transverse speed of workpiece 20 cm/min, which shows the maximum percentage change in the surface roughness value. Confirmation experiments have been performed at optimal combination. The lowest Ra value of 85 nm (nanometre) has been achieved from the initial value of 410 nm (nanometre) in the finishing duration of 90 min. The roughness profiles, scanning electron microscopy (SEM) test and reflection test show that the current finishing process can meet high standards for surface quality that aren't possible with conventional methods.

Sampling Error of TOC swab in Pharmaceutical Cleaning Verification

Cleaning verification is a critical process for patient safety in pharmaceutical manufacturing in order to keep cross-contamination below acceptable limits. A common cleaning verification method is the total organic carbon (TOC) swab. Others have studied the variances of different factors on the TOC swab in order to establish the best swab method. This paper attempts to quantify the sampling error of the TOC swab in the actual sampling situation using simulation. The study investigates the variability on the drug product recovery due to different analysts, concentration, steel finish and position, as well as the estimation of the given swab area. The results demonstrate that the sampling error leads to a large variation in TOC results. For areas estimated in the laboratory, it leads to an increase in limit of detection, LOD, with 60%, while for areas estimated in a tank, the LOD cannot be determined due to the large heteroscedasticity. Thus, this paper is also to be considered as an invitation to discuss and further investigate the TOC sampling error in the pharmaceutical industry.

Optimization of turning process variables for surface integrity using taguchi technique

The selection of proper machining parameters is crucial for the production of a product of desired quality. The Taguchi method will accomplish this. For this work, using tin coated tungsten carbide method, SS-321 work parts are placed onto CNC lathe machine. Stainless steel machining (SS-321) has issues such as worn-out tool and high roughness to the surface. The key reasons for choosing SS-321 grade as workpiece material is the issue of the machining process related with super finishing of Stainless Steel. For this work twenty-seven experiments were carried out on stainless steel (SS-321), as per Taguchi’s L27 orthogonal array. Data analysis was carried out using Taguchi response table method and ANOVA. Following this method, a confirmation experiment was performed to assess the surface integrity change. Turning machining parameter levels to reduce surface roughness were A1B3C1 i.e., depth of cut 0.5 mm, cutting speed of 120 m / min and feed of 0.2 mm / rev. ANOVA table represented the parameters which mostly affected the surface roughness with 76.27% contribution of depth of cut which is maximum followed by feed (7.72%), and effect of speed (3.48%) is insignificant. The research also shows that this approach can efficiently boost the surface finish of the turning process.

Exploration of Desirability Function Analysis-Based Particle Swarm Optimization for Magnetic Abrasive Finishing of Mild Steel

Analysis of surface roughness, temperature and hardness of the finished surface is beneficial to retain the desired surface finish of the workpiece via the magnetic abrasive finishing (MAF) process. In this work, “change in roughness” ([Formula: see text]Ra), “raise in temperature” ([Formula: see text]) and “change in hardness” ([Formula: see text]) were opted for the multi-objective meta-heuristic optimization to minimize their impact on the finished surface of mild steel. Taguchi [Formula: see text] orthogonal array was used to obtain the experimental data on mild steel. The desirability fitness function (DFF) was developed to convert multi-responses to a single response. Finally, particle swarm optimization (PSO) was used for a higher-level decision-making and a meta-heuristic optimization approach, i.e. desirability function analysis-based PSO (PSO-DFA), was developed to obtain the best performance condition for surface finish. The best optimal setting obtained by using PSO-DFA included a working gap of 1.5[Formula: see text]mm, an abrasive weight of 15[Formula: see text]g, a voltage of 6[Formula: see text]V and a rotational speed of 50[Formula: see text]rpm. This setting has been selected based on the highest PSO-DFA value predicted by the meta-heuristic optimization approach and improved by 38.20% in comparison with DFA, that shows a satisfactory performance.

Designing a scheduling decision support system for the skin pass line: A case study of the steel finishing line

In this paper, we investigate the scheduling policies in the iron and steel industry, and in particular, we formulate and propose a solution to a complicated problem called skin pass production scheduling in this industry. The solution is to generate multiple production turns for the skin pass coils and, at the same time, determine the sequence of these turns so that productivity and product quality are maximized, while the total production scheduling cost, including the costs of tardiness, flow of material, and the changeover cost between adjacent and non-adjacent coils, is minimized. This study has been prompted by a practical problem in an international steel company in Iran. In this study, we present a new mixed integer programming model and develop a heuristic algorithm, as the commercial solvers would have difficulty in solving the problem. In our heuristic algorithm, initial solutions are obtained by a greedy constraint satisfaction algorithm, and then a local search method is developed to improve the initial solution. The experimental results tested on the data collected from the steel company show the efficiency of the proposed heuristic algorithm by solving a large-sized instance in a reasonable computation time. The average deviation between the manual method and the heuristic algorithm is 30%. Also, in all the components of the objective function, the algorithm performs better compared to the manual method. The improved values are greater than 15. In addition, we develop a commercial decision support system for the implementation of the proposed algorithm in the steel company.

Investigation of machinability criteria during micro-abrasive finishing of SUS-304L steel using fuzzy combined with WASPAS approach

This article deals with the optimization of process parameters involving in the magnetic abrasive finishing (MAF) process to achieve the optimum responses. In order to choose to the best decisive course of action, we have used the weighted aggregated sum product assessment (WASPAS) method. This method is a multi-criteria decision-making process; here, it optimizes the six process parameters of the MAF process. The WASPAS is used to find the optimum parametric setting of the process parameter for the combined effect of the output responses, i.e., percentage improvement in surface finish (PISF) and material removal rate (MRR) in terms of total relative importance index Qi. The process parameters are namely rotational speed, working gap, particle size of abrasive, quantity of abrasive, finishing time and magnetic flux density, and responses are PISF and MRR. The analysis of variance is implemented not only to find out the percentage contribution of each of the process parameters but also to know the effect of interaction between any two process parameters. Finally, a regression equation is developed as per the backward propagation method and the predicted values are estimated from the equation. Those values are further compared with the experimental values.

Microstructure and texture evolution in warm rolled API 5L X70 pipeline steel for sour service application

The evolution of microstructure and texture of API 5L X70 pipeline steel after warm rolling treatments has been studied using X-ray diffraction and electron backscatter diffraction (EBSD). Our investigations revealed that the microstructure after the rough rolling stage consist of coarse grained ferrite and bainite clusters, while the specimens finished rolled at 600 °C and 700 °C consist mainly of elongated ferrites and a well recrystallized polygonal shaped ferrite grains. EBSD investigations confirmed that dynamic recovery was dominant during the rough rolling stage; whereas a partial recrystallization and a well recrystallized structure were observed during finish rolling at 600 °C and 700 °C respectively. X-ray macro-texture measurement showed that the intensity of the desired γ-fiber texture is dependent on the finish rolling temperature. The finish rolling treatments lowered the fractions of the Goss, Brass, S and Copper texture components. However, higher fractions of the Goss {001}〈100〉, brass ({110}〈112〉), S ({123}〈634〉) and Copper ({112}〈111〉) were observed in steels rolled at 600 °C finish rolling temperature. Strong texture inhomogeneity during warm rolling was observed. The γ-fiber is seen to be better formed at the mid thickness compared to the surface. Most grains at the mid thickness were oriented in the {111}‖ND and {001}‖ND at both finish rolling temperatures. The finish rolling temperature played a key role in the development of texture such that the recrystallization of grains in steel finish rolled at 700 °C favoured the development of the γ-fiber texture.

Abrasive Flow Finishing of Stainless Steel 304 Biomedical Devices

Abrasive Flow Finishing of Stainless Steel 304 Biomedical Devices

Experimental investigations into transient roughness reduction in ball-end magneto-rheological finishing process

ABSTRACTBall-end magneto-rheological finishing (BEMRF) process is a variant of magneto-rheological finishing (MRF) which is capable of finishing magnetic as well as nonmagnetic materials to finish surfaces up to the order of nanometers. The development of this process has been fairly recent and the literature has focused on quantifying and analyzing the effects of finishing on different materials with it. This research work presents a time-based roughness reduction study of BEMRF process to find out the behavior of machining parameters in finishing over lengthy time intervals. EN31 steel has been chosen as the work material for this study. Firstly, a machining parameter optimization is carried out for finishing of EN31 steel with BEMRF process. A detailed time-based experimental study is then carried out to find the effect of time on finishing with BEMRF process. The time-based study revealed a transient roughness reduction phenomenon in which a particular set of machining parameters was capable of reducing the surface roughness only up to a limited roughness value. The study concluded a database for finishing of EN31 steel with BEMRF process which can be used for optimum time-based finishing with BEMRF process.

Electroplating wastes

AbstractElectroplating and other metal finishing industries, like every metal and metallurgical industry, are associated with the generation of waste. Spent electroplating baths, waste pickle liquors, etching solutions and rinse waters from electroplating units and steel finishing operations are complex solutions containing acids and several hazardous metals. It is compulsory, for environmental and economic reasons, to treat these solutions for recovering acid, metals and/or reusing these solutions/waters. This article is a review on the characterization of the wastes that are generated in electroplating industry, steel processing and copper etching in printed circuit boards manufacture, as well as on the treatment and regeneration methods of such streams. Various techniques, such as neutralization, crystallization, evaporation, pyrohydrolysis, electrodialysis, ion exchange, classical solvent extraction and membrane-based solvent extraction are presented, their advantages and disadvantages being scrutinized.

НЕПРЕРЫВНЫЙ КОНТРОЛЬ ТЕМПЕРАТУРЫ ЖИДКОЙ СТАЛИ В ТЕХНОЛОГИЧЕСКИХ АГРЕГАТАХ МЕТАЛЛУРГИЧЕСКОГО ПРОИЗВОДСТВА

The article considers the method of continuous objective control of the temperature of liquid steel in metallurgical aggregates of steelmaking and foundry industries. The method is characterized by a sufficiently high accuracy (±9 °С), simple operation, reliability and service life, exceeding the service life of the refractory masonry of the process unit. The aim of the work is to develop a method for the continuous monitoring of the temperature of liquid steel in technological units of metallurgical production. The basis of the adapted method is the solution of the inverse heat conduction problem (usually incorrect), when, at known temperatures, temperatures on the layers of active thickness of refractory masonry (up to 80 mm) restore the temperature at the “melt – refractory masonry” boundary. The new methodological approach to the elements of novelty in the work is the continuous objective control of the temperature of liquid steel in metallurgical aggregates. The results of the justification and the technical solution, the results of the study of the accuracy of the method on the experimental bench and in real production conditions on the arc steel furnace are presented. The obtained experimental data reflect the sufficiently high accuracy and efficiency of the considered calculation method of continuous monitoring of the temperature of liquid melt. This task is relevant in the conditions of using of steel-furnace aggregates as efficient installations for obtaining the melt heated to a certain temperature. It is advisable to use the method in installations of out-of-furnace finishing of steel “furnace – ladle”. The calculation method is designed for software implementation using domestic low-cost microprocessor controllers both as an autonomous information technical control means and as part of an integrated element in the process automation system of steelmaking.

Transuranic contamination of stainless steel in nitric acid

Stainless steels coupons have been exposed to transuranic species in conditions representative of those found in a spent nuclear fuel reprocessing plant. Stainless steel was prepared to different surface finishes and exposed to nitric acid of varying concentrations containing 237Np, 239Pu or 243Am for one month at 50 °C. Contamination by these transuranics has been observed on all surfaces exposed to the solution through the use of autoradiography. This technique showed that samples held in 4 M HNO3 bind 2–3 times as much radionuclide as those held in 10.5 M HNO3. It was also found that the polished steel surfaces generally took up more transuranic contamination than the etched and “as received” steel finishes. The extent of corrosion on the steel surfaces was found, by scanning electron microscopy, to be greater in solutions containing Np and Pu in comparison to that observed from contact with Am containing solutions, indicating that redox activity of transuranics can influence the mechanism of stainless steel corrosion.

DEVELOPMENT OF AUTOMATIC SYSTEM OF GAS-DYNAMIC CUT-OFF OF SLAG FOR CONVERTER WITH ROTATING VESSEL SHELL

The steelmaking unit for the processing of poor-quality charge and metal-containing wastes with a high content of harmful impurities must satisfy to some requirements which are considered at the article. Also the expediency of using the oxygen converter with rotating vessel shell as a prototype is justified. To increase the efficiency of such converter, it is proposed to supply it with a system of gas-dynamic slag cut-off at automatic mode during the steel tapping into the casting ladle. The proposed system is structurally a twin lever mechanism ensuring (during the metal overflow into the ladle through the edge of converter's mouth) holding at the constant distance from it the gas distribution chamber with slotted nozzles, from which flat gas jets run under excess pressure, directed at a given angle of attack to the surface of slag melt covering the teemed steel. Due to the dynamic impact of these jets on the layer of liquid slag, it is pushed away from the edge of the mouth of the inclined vessel shell towards its bottom, i.е. it is retained in the bath of melting unit. Synchronous movement of the structural elements of the lever mechanism with the end part of converter’s mouth is achieved by force interaction of the stops rigidly fixed on the supporting ring of the melting unit with swivel arms kinetically connected with the gas distribution chamber. At the same time, activation of the gas-dynamic system of slag cut-off and its shutdown occur automatically by a mechanical connection. After the finishing of steel tapping the slag is poured into the bowl, turning the vessel shell in the opposite direction from the steel casting ladle. The results of experimental verification of the operation of the proposed converter slag gas-dynamic cut-off system performed on its model confirmed correctness of the accepted technical solutions. The practical application of this development will significantly reduce the material losses associated with the ingress of a large amount of aggressive converter slag into the casting ladle (deoxidizing and ligature burning, intensive wear of the refractory lining and the possibility of metal rephosphorization).

The Influence of Microstructure and Non-Metallic Inclusions on the Machinability of Clean Steels

This study focused on the evaluation of the machinability of different carburising steel grades by using a cemented carbide cutting tool during semi finishing of steel. The effect of the steel comp ...

Influence of Abrasive - Free Ultrasonic Finishing Process of Steel on Wear

The intensity of wear and particles formation are important factors at practical application of rotating machine components, because of negative effects on operability of the machines. The presence of undesired wear particles, for example in lubricating systems, poses a risk in terms of subsequent accelerated wear of lubricated points. In the extreme case, the negative impact of the wear particles leads to seizure of lubricated points. The aim of the research was to compare the classical machining and abrasive - free ultrasonic finishing (bufo) of steel. Ultrasonic set I-4 consisting of the ultrasonic generator (output power 630 W) with working frequency 22 kHz ± 10% was used for preparation of test surface. There were compared three different process fluids containing nanoparticles during abrasive - free ultrasonic finishing. In order to describe machined surface there was used measurement of surface roughness, hardness HBW 2.5/187.5 and results of microscopy. Research was focused on determining resistance of machined surfaces, using a standardized test Reichert M2 tester. Number of wear particles and their morphology are important for practical application. Wear particles were analyzed by automatic particle counter LaserNet Fines-C.

High Speed Milling of Hardened Steel Convex Surface

This paper presents a contribution to hardened tool steel milling studies. High speed milling is largely utilized to substitute some EDM and polishing operations, mainly in hardened tool steel finishing. Tool path strategy may either enable good surface finish or contributes to generate high roughness values and poor surface finish. Tool inclination (angle between tool axis and workpiece surface) influences the system response to vibration. In this work, several milling experiments were performed in a circular convex AISI D6 hardened steel workpiece, having as input variables feed direction (upward and downward the circle) and tilt angle (tool inclination). The main results indicate that upward tool path presented mostly high roughness values which were also influenced by tool inclination. Downward tool path presented low roughness values and was less influenced by tool inclination. Upward tool path and positive tool inclination should be avoided because they presented roughness values incompatible to EDM process substitution.

Microstructural Characteristics with Various Finish Rolling Temperature and Low Temperature Toughness in Hot Rolled Nb–Ti Ferritic Steel

In order to investigate the effects of finish rolling temperature on the microstructural characteristics and fracture mechanism of Nb–Ti ferritic steel, the samples with various finish rolling temperature have been observed by optical microscopy, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. The results indicated that both ferrite grain size and volume fraction of (Nb,Ti)C precipitates decreased with the decreasing finish rolling temperature, but the size of (Nb,Ti)C precipitates changed little with the finish rolling temperature. All of these factors caused the yield strength, tensile strength and elongation remained similar. However, the low temperature toughness was significantly influenced by the finish rolling temperature. Based on the observation results of fracture surface of samples tested at −40°C, the fracture type of steels with finish rolling temperature of 940°C and 910°C was brittle, while the fracture of steel with finish rolling temperature of 880°C was ductile. At last, the crack initiation and propagation mechanism is elucidated in details. At −40°C, both intergranular cracks and transgranular cracks existed in the steels finish rolled at 940°C and 910°C, and only microvoides were observed in the steel finish rolled at 880°C with high toughness.