American Iron And Steel Institute Research Articles

Energy Consumption and Saving Analysis for Laser Engineered Net Shaping of Metal Powders

With the increasing awareness of environmental protection and sustainable manufacturing, the environmental impact of laser additive manufacturing (LAM) technology has been attracting more and more attention. Aiming to quantitatively analyze the energy consumption and extract possible ways to save energy during the LAM process, this investigation studies the effects of input variables including laser power, scanning speed, and powder feed rate on the overall energy consumption during the laser deposition processes. Considering microhardness as a standard quality, the energy consumption of unit deposition volume (ECUDV, in J/mm3) is proposed as a measure for the average applied energy of the fabricated metal part. The potential energy-saving benefits of the ultrasonic vibration–assisted laser engineering net shaping (LENS) process are also examined in this paper. The experimental results suggest that the theoretical and actual values of the energy consumption present different trends along with the same input variables. It is possible to reduce the energy consumption and, at the same time, maintain a good part quality and the optimal combination of the parameters referring to Inconel 718 as a material is laser power of 300 W, scanning speed of 8.47 mm/s and powder feed rate of 4 rpm. When the geometry shaping and microhardness are selected as evaluating criterions, American Iron and Steel Institute (AISI) 4140 powder will cause the largest energy consumption per unit volume. The ultrasonic vibration–assisted LENS process cannot only improve the clad quality, but can also decrease the energy consumption to a considerable extent.

Interacted buckling failure of thin-walled irregular-shaped aluminum alloy column under axial compression

Interacted buckling behaviors and ultimate strength of thin-walled aluminum alloy columns with irregular-shaped cross section were studied using a verified Finite Element Model (FEM). Six interacted buckling failure modes were studied, which were: (1) the interaction of Local bucking and sectional Yielding (LY); (2) the interaction of Local and Global buckling (LG); (3) the interaction of Distortional buckling and sectional Yielding (DY); (4) the interaction of Distortional and Global buckling (DG); (5) the interaction of Local bucking, Distortional bucking and sectional Yielding (LDY or DLY); and (6) the interaction of Local, Distortional and Global buckling (LDG). The load-axial displacement curve, the deflection-axial displacement curve, the development of the axial stress at different positions in the section at mid-span, the out-of-plane displacement at failure along the column length and the axial stress distribution at failure across the section at mid-span were presented. The local buckling and distortional buckling were detected by the turning points on the load-axial displacement curves. The out-of-plane displacement along the column length at failure was used to illustrate the failure mode of the column. Ultimate strengths and failure modes of 174 columns failed by interacted buckling failure modes were investigated by both FEM and current design approaches. For the ultimate strength of the columns under DY failure mode, the results predicted by North American specification for the design of cold-formed steel structural members of American Iron and Steel Institute (AISI) were higher than FEM simulation results. The ultimate strength predicted by American Aluminum Design Manual (AA), Direct Strength Method (DSM), European Code (EN1999) and Chinese Design Specification for Aluminum Alloy Structures (GB50429) were lower than FEM simulation results, no matter what kind of failure modes the column encountered. Mean values of PAA/PFEA, PEC9/PFEA and PGB/PFEA were 0.81, 0.79 and 0.74. DSM could precisely predict the Global buckling (G), LG and DY failure modes. However, for the columns failed by LY, DG, LDY and LDG, they were LG, G, DY and LG when predicted by DSM, respectively. The applicability of DSM to thin-walled aluminum alloy columns with irregular-shaped cross section should be investigated further.

Tool Wear and Surface Roughness in Machining AISI D2 Tool Steel

Background: Along with the recent developments in hard milling technology, tool wear and surface integrity has become a very important consideration in order to achieve optimum cutting conditions. The purpose of this research paper is to study the tool wear and surface roughness while machining American Iron Steel Institute (AISI) D2 tool steel using coated carbide tool. Method: A series of cutting tests have been carried out to verify the change in surface roughness of the workpiece due to increasing tool wear. The tests have been done under various combinations of speed and feed in the dry condition. The machined surface was evaluated in terms of surface roughness. Findings: Mechanical wear or abrasion is typically dominant during the initial cutting. Thermal wear is dominant at higher cutting speeds due to high cutting temperature. Majority of the tool wear modes were due to flank face wear and excessive chipping on the tool edge. The results also reveal that the variation in cutting speed and feed would not significantly change the surface roughness of the machined surface. Generally, surface produced are very smooth with Ra values in the range of 0.1 μm to 0.37 μm. Conclusions: Roughness values (Ra and Rmax) were found to be almost constantly with the progression of the flank wear under all cutting conditions. It indicates that surface roughness did not play a significant role in limiting tool life.

Multiresponse Optimization of Laser Cladding Steel + VC Using Grey Relational Analysis in the Taguchi Method

Laser cladding of metal matrix composite coatings (MMCs) has become an effective and economic method to improve the wear resistance of mechanical components. The clad quality characteristics such as clad height, carbide fraction, carbide dissolution, and matrix hardness in MMCs determine the wear resistance of the coatings. These clad quality characteristics are influenced greatly by the laser cladding processing parameters. In this study, American Iron and Steel Institute (AISI) 420 + 20% vanadium carbide (VC) was deposited on mild steel with a high powder direct diode laser. The Taguchi-based Grey relational method was used to optimize the laser cladding processing parameters (laser power, scanning speed, and powder feed rate) with the consideration of multiple clad characteristics related to wear resistance (clad height, carbide volume fraction, and Fe-matrix hardness). A Taguchi L9 orthogonal array was designed to study the effects of processing parameters on each response. The contribution and significance of each processing parameter on each clad characteristic were investigated by the analysis of variance (ANOVA). The Grey relational grade acquired from Grey relational analysis was used as the performance characteristic to obtain the optimal combination of processing parameters. Based on the optimal processing parameters, the phases and microstructure of the laser-cladded coating were characterized by using x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS).

Effects of Cr2N Precipitation on the Antibacterial Properties of AISI 430 Stainless Steel

Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainless steels have been widely applied as biomaterials, including the austenitic 304 stainless steel, the austenitic 316 stainless steel, the duplex 2205 stainless steel, and the ferritic 430 stainless steel. In order to reduce the occurrence of infections resulting from biomaterial implants, instruments, and medical devices, Cu2+ and Ag2+ ions have been added onto biomaterials for increasing the antibacterial properties, but they are known to damage biofilm. The occurrence of nanoparticles can also improve the antibacterial properties of biomaterials through various methods. In this study, we used Escherichia coli and analyzed the microstructures of American Iron and Steel Institute (AISI) 430 stainless steel with a 0.18 mass % N alloy element. During a lower temperature aging, the microstructure of the as-quenched specimen is essentially a ferrite and martensite duplex matrix with some Cr2N precipitates formed. Additionally, the antibacterial properties of the alloy for E. coli ranged from 3% to 60%, consistent with the presence of Cr2N precipitates. When aged at a lower temperature, which resulted in nano-Cr2N precipitation, the specimen possessed the highest antibacterial activity.

Influence of free energy on the attachment of Salmonella Enteritidis and Listeria monocytogenes on stainless steels AISI 304 and AISI 316

Abstract Bacterial attachment to stainless steels AISI (American Iron and Steel Institute) 304 and 316, the preferred material choices for food equipment, is a very important food safety consideration. The purpose of the present study was to investigate the attachment of two important food pathogens on commercial samples of these surfaces focusing on the influence of material topography characterized by Atomic Force Microscopy and considering the hydrophobicity and free energy of interaction, determined by measuring contact angle and application of thermodynamic theory principles. Results showed that S. Enteritidis and Listeria monocytogenes were able to attach to samples of stainless steels, however, initially (t = 0), the number of adhered S. Enteritidis (2.55 log CFU/cm 2 ) was higher than L. monocytogenes (1.68 logCFU/cm 2 ). Corroborating these results, the adhesion was thermodynamically more favorable for S. Enteritidis . Even though, the number of adhered cells were similar on both stainless steels samples, negative total energy was higher on AISI 316, for both bacteria. Moreover, the surface's roughness (0.032 μm and 0.021 μm) and hydrophobicity of cells and materials did not show a positive correlation with bacterial adherence.

Estimation of ultimate strength in single shear bolted connections with aluminum alloys (6061-T6)

An experimental investigation for the structural behavior of single shear bolted connection fabricated with aluminum alloys (6061-T6) has been carried out by Kim et al. It is found that ultimate strengths caused by curling (out-of-plane deformation in the direction of plate thickness) were reduced for some specimens with long end distances parallel to the direction of loading. In this paper, finite element analysis model has been developed on the basis of existing experimental results and analysis results were compared with the test results in order to verify the validity of finite element analysis method for predicting the ultimate behaviors of bolted connections. Additional analyses with extended variables such as end distance and edge distance were performed. Strength reduction ratio by curling and the condition of curling occurrence were investigated. Moreover, ultimate strength of analysis result was compared with design strength by American Aluminum Association (AAA) and American Iron Steel Institute (AISI) design standards. Modified strength equations were suggested considering effective shear stress in block shear fracture and curling effect by bolt bearing action.

Direct strength prediction of web crippling failure of beams under ETF loading

This paper proposes a new approach to predict the web crippling failure load of cold-formed steel beams under External Two Flange (ETF) loading using the Direct Strength Method (DSM). After the description of the existing test data, Eurocode 3 (Comité Européen de Normalisation (CEN), 2006) [1] and the North-American Specification (American Iron and Steel Institute (AISI), 2012) [2] are used to predict the corresponding web crippling failure loads and the accuracy of such predictions is briefly assessed. In order to obtain additional information on the web crippling behaviour of each test specimen, non-linear numerical simulations are performed. Since the calibration of the DSM-based design expressions requires the previous calculation of (i) elastic buckling loads and (ii) plastic strengths/loads, two procedures are presented to achieve these goals. While the buckling loads are determined using the GBTWEB software, specifically developed for this purpose, the plastic loads are calculated by means of analytical expressions based on yield-line models. By adopting a non-linear regression procedure, the coefficients of a DSM-based formula are determined on the basis of the set of 128 experimental results available and the corresponding buckling and plastic load values. In spite of the different cross-sections, fastening conditions and test set ups considered in the calibration procedure, it is possible to establish a clear relationship between the web crippling slenderness and the nominal-to-plastic load ratio. Finally, it is shown that the developed/proposed DSM-based formula for ETF web crippling design yields reliable predictions, since they are associated with a LRFD (Load and Resistance Factor Design) resistance factor ϕ=0.81, which is located within the range of values currently adopted in the 2012 NAS (American Iron and Steel Institute (AISI), 2012) [2].

On the machinability of die/mold D2 steel material

The presented paper experimentally studies the machining of American Iron and Steel Institute (AISI) D2 steel as a frequently used material in die and mold making industry. Several experimentations have been carried out using different cutting conditions such as feed rate, depth of cut, and machining time. The consequent effects of these parameters on the tool and workpiece in terms of tool wear, cutting forces and power, and workpiece surface integrity (surface roughness) have been recorded to investigate the machinability of D2 steel material. The results mainly reveal that depth of cut, feed rate, and machining time are the most dominant parameters that play an important role in machinability characteristics of D2 steels.

Boriding kinetics and mechanical behaviour of AISI O1 steel

In this work, American Iron and Steel Institute (AISI) O1 steel was pack borided in the temperature range of 1123–1273 K for treatment times between 2 and 8 hours. A kinetic model was proposed for estimating the boron diffusion coefficients through the Fe2B layers. As a result, the boron activation energy for the AISI O1 steel was estimated as 197·2 kJ mol− 1. This value of energy was compared to the literature data. In addtion, to extend the validity of the present model, two additional boriding conditions were done. The Fe2B layers grown on AISI O1 steel were characterised by use of the following experimental techniques: scanning electron microscopy, X-ray diffraction analysis and Daimler-Benz Rockwell-C indentation technique. Finally, the scratch and pin on disc tests for wear resistance were respectively performed using an LG Motion Ltd and a CSM tribometer under dry sliding conditions.

Investigation of effects of nanofluids on turning of AISI D2 steel using minimum quantity lubrication

Large quantity of metal working fluid used for each day in industry for metal cutting operations like milling, drilling, stamping, turning etc. But high consumption of metal working fluids creating some big problems like occupational diseases to workers and creating environmental pollution and also increasing the machining cost. To overcome the drawbacks of metal working fluids a new technique which provides better results by using lesser amount of metal working fluids is known as Minimum quantity lubrication. The performance of minimum quantity lubrication using conventional cutting fluids can be further improved with the help of nanofluids. Nanofluids having suspended solid nanometer sized particles in base oil which improves the thermal conductivity and lubrication properties. The aim of this study was to investigate the effects of Carbon nanotubes on turning of American Iron and Steel Institute (AISI) D2 steel using minimum quantity lubrication. The high carbon high chromium AISI D2 was turned at different speed, feed and using tungsten carbide insert (CNMG 120408). The experiment was designed and analyzed with the help of Taguchi design and analysis in MINITAB 16. The optimized results indicate that minimum quantity lubrication using nanofluid (NFMQL) shows promising results over minimum quantity lubrication technique using conventional cutting fluid in terms of cutting zone temperature, and surface roughness.

Performance evaluation of vegetable emulsifier based green cutting fluid in turning of American Iron and Steel Institute (AISI) 1040 steel – an initiative towards sustainable manufacturing

Cutting fluids are widely used in machining. However they pose several health and environmental issues. Several works on vegetable-based cutting fluids have been reported in literature but the prime focus of these works was the replacement of mineral oil with vegetable oil while the emulsifier, which is often the root-cause of all these issues, was never replaced. The present work is an attempt to replace both the mineral oil and petroleum-based emulsifier with vegetable-based alternatives (sesame oil and coconut based emulsifier) and produce a new class of sustainable cutting fluids. The formulated cutting fluids were compared with regular cutting fluid while machining American Iron and Steel Institute (AISI) 1040 steel. The findings show that the formulated fluid with 10% vegetable emulsifier content exhibits a performance similar to the regular cutting fluid in terms of cutting temperatures, tool wear and surface roughness. The performance of the 10% coconut emulsifier fluid was better than other fluids with coconut emulsifier. However, cutting forces were less when the regular cutting fluid was used. The formulated fluids can be used in situations with low cutting forces but high cutting temperatures, like machining at higher speeds. The major contribution of the work is the replacement of regular petroleum-based emulsifier with an eco-friendly alternative, in addition to using vegetable oil.

Experimental testing of cold-formed built-up members in pure compression

Cold-formed built-up members are compression members that are common in multiple areas of steel construction, which include cold-formed steel joints and stud walls. These members are vulnerable to unique buckling behaviors; however, limited experimental research has been done in this area. Give this gap, experimental testing of 71 built-up members was conducted in this study. The variations of the test specimens include multiple lengths, intermediate welds, orientations, and thicknesses. The experimental testing was devised to observe the different buckling modes of the built-up C-channels and the effects of the geometrical properties; to check for applicability of multiple intermediate welding patterns; and to evaluate both the 2001 and 2007 editions of the American Iron and Steel Institute (AISI) Specification for built-up members in pure compression. The AISI-2001 and AISI-2007 were found to give inconsistent results that at times were un-conservative or overly conservative in terms of axial strength. It was also found that orientation of the member has an important impact on the maximum failure load on the member.

Corrosion degradation of AISI type 304L stainless steel for application in nuclear reprocessing plant

The degradation of materials involving corrosion in handling nitric acid in the spent fuel nuclear reprocessing plant is a serious issue. In the present work, the corrosion resistance of American Iron and Steel Institute (AISI) type 304L stainless steel (SS) and nitric acid grade (NAG) type 310L SS in 1 to 11.5 M HNO3 and boiling 15.65 M HNO3 was evaluated. In both the alloy steels, the open circuit potential and corrosion potential are shifted to more noble potential with increasing concentrations. However, the passive current density was not affected, and the transpassive potential was shifted to higher potential with increasing concentrations. The corrosion rate measured in boiling 15.65 M HNO3 after 240 h shows a much lower corrosion rate in type 310L SS (∼0.06 ± 0.012 mm/y) then type 304L SS (∼0.18 ± 0.02–0.2 ± 0.001 mm/y). These observations are corroborated with the scanning electron microscope (SEM) morphologies that show severe intergranular corrosion (IGC) attack in type 304L SS then in type 310L SS. The X-ray photoelectron spectroscopy (XPS) study of the passive oxide films of both alloy steels shows the presence of Cr2O3 and SiO2, and the depth profile indicated predominant Si enrichment.

면외변형의 영향을 받는 알루미늄합금 일면전단 볼트접합부의 내력평가에 관한 실험적 연구

Many researchers have studied the structural performance of bolted connection with aluminum alloys and design specifications for in-plane fracture (net-section, bearing and block shear fractures) of bolted connection have been improved by their study results. However, it can be known from study results conducted by Kim et al. that curling (out-of-plane deformation) could be negative effect (strength reduction) on ultimate strength of single shear bolted connection fabricated with 3.0mm thick aluminum alloy(6061-T6) plate. Strength reduction for curled single shear specimens obtained from the comparison of test results for double shear bolted connections ranged from 4% to 30%. In this paper, additional experiments are performed in order to investigate the influence of curling on ultimate strength and curling occurrence condition for 4.0mm thick bolted connection. Main variables are end distance and edge distance. In all specimens, strength reduction by curling was observed. Strengths obtained from test results were compared with design strengths predicted by AISI (American Iron and Steel Institute) and AAA (American Aluminum Association) design rules. Bearing factor considering curling effect and hole deformation limit was discussed.

Experimental investigation on strength and curling influence of bolted connections in thin-walled carbon steel

Experimental studies regarding the influence of curling on the ultimate strength of cold-formed stainless steel bolted connections have been carried out by Kim et al. Basic data and modified equations for predicting the structural behaviors considering strength reduction due to curling through the finite element analysis method have also been suggested by previous researchers.In this paper, single shear bolted connections fabricated with four bolts and thin-walled carbon steel commonly utilized in light-weight structural members were tested to investigate the fracture mechanism and curling influence on the ultimate strength. Main variables for test specimen are plate thicknesses and end distances parallel to the direction of loading. Curling (out-of-plane deformation in the direction of plate thickness) also occurred in thin-walled carbon steel bolted connections with a large end distance and thinner plate like previous cold-formed stainless steel connections. The curling occurrence reduced suddenly the ultimate strength of single shear carbon steel bolted connections and the influence pattern of curling on strength was affected according to the plate thickness and end distance. Current design specifications for block shear strength with the combination of tensile fracture and shear fracture are summarized and the ultimate strengths of test results are compared to the predicted design strengths. AISI (American Iron and Steel Institute) and EC3 (Eurocode 3) made conservative estimates of ultimate strength for thin-walled carbon steel bolted connections with no curling, whereas AIJ (Architectural Institute of Japan) and SSBA(Stainless Steel Building Association) manuals provided a good prediction for ultimate strength and fracture mode. Modified strength equations were recommended respectively for bolted connections with typical block shear fracture considering shear stress factor and severe curling accompanied by strength reduction.

Experimental investigation of short steel columns with localized corrosion

To investigate the effect of corrosion on the axial capacity of steel bridge piles, a total of 13 H-shaped short columns were tested under monotonic axial load. The columns were machined to simulate different degrees and patterns of corrosion. The remaining axial capacity of the deteriorated members was assessed. To simulate the corrosion, webs and flanges were milled near the mid-height of the columns to reduce their thicknesses. The experimental results were compared to the axial capacities predicted by the design provisions of the American Institute of Steel Construction (AISC), American Association of State Highway and Transportation Officials (AASHTO), and American Iron and Steel Institute (AISI). The results of this study indicate that the degree of flange corrosion is the single factor that has the most significant effect on the column capacity. Other factors, including unsymmetry of the corrosion pattern or reduction of the flange width had a minor influence on the capacity. The results also indicate that, among the design methods considered, the effective width method recommended by AISI provides the best prediction of the capacity of severely deteriorated steel columns.

Corrosion inhibition of AISI 1020 steel based on tungstate anion and amoxicillin as corrosion inhibitors in 0.05 mol l−1NaCl solution or inserted into cellulose acetate films

Sodium tungstate and amoxicillin were used separately or combined in a solution containing 0.05 mol l−1 NaCl or inserted into cellulose acetate films as a corrosion inhibition method for American Iron and Steel Institute (AISI) 1020 steel. The electrochemical behavior of AISI 1020 steel was characterized using open-circuit potential, anodic polarization and electrochemistry impedance spectroscopy. The inhibitor effect of tungstate anions was proved, and its combination with amoxicillin was considered inferior when tungstate was used alone. This behavior was attributed to weaker adsorption of amoxicillin when compared with the adsorption of tungstate anion both deposited on the alloy and into the cellulose acetate film on the steel. Copyright © 2014 John Wiley & Sons, Ltd.

Analysis of friction welding parameters on the mechanical metallurgical and chemical properties of AISI 1035 steel joints

In this present work, the analysis of process parameters on mechanical, metallurgical and chemical properties of American Iron and Steel Institute (AISI) 1035 steel rods of 12mm diameter joints produced by friction welding is analyzed. The joints made with various process parameter combinations are subjected to tensile tests, hardness test and cyclic potentiodynamic polarization tests. The properties such as tensile strength, notch tensile strength, yield strength, % elongation, and vickers’s hardness, fully deformed zone (FDZ), flash formation and pitting corrosion has been analyzed for high level and low level process parameters. The optimized process variable is obtained by using Response Surface Methodology (RSM). The integrity of the welds has been investigated using high magnification optical microscopy. The fracture surface of the tensile test specimen is analyzed by using Scanning Electron Microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDAX).

Effect of powder particle size on wear resistance of plasma sprayed molybdenum coating

Plasma-sprayed molybdenum coatings are used in automotive, aerospace, pulp and paper industries in order to guard the machine parts against wear and corrosion. In this work, an attempt has been made to study the effect of particle size on wear behaviour of molybdenum coated steel. Two types of Mo coatings were deposited on American Iron and Steel Institute (AISI) 1020 steel substrate, one is with particle size of 15–40 µm (type I) and another one is with 40–90 µm (type II) using plasma spraying. The microstructures and worn surface morphologies of the coatings were analysed by means of X-ray diffractometer and scanning electron microscopy. It was found that the as-sprayed type I and type II coatings consist of molybdenum (Mo) as the major phase and molybdenum oxide (MoO2) as the minor phases. For the evaluation of influence of coating powder particle size on wear characteristics, the sliding wear tests were performed on a pin-on-disc apparatus. The variation of volume loss with applied load, sliding speed and sliding distance was monitored. The type I sprayed coating exhibits better wear resistance. Tribological testing was also supported by metallographic examination for the identification of wear mechanisms. It was verified that the wear of coating is dominated by fracture of splats, crack propagation, delamination and plowing.