Thick Mild Steel Research Articles

Experimental Investigation of Optimal Welding Parameters and Mechanical Properties of Shielded Metal Arc Welded Mild Steel Plates

This study focuses on achieving enhanced mechanical properties of the welded joints, which is critical for the applications of mild steel (MS) plates in various industries. In this regard, a systematic approach is used to adjust welding parameters such as welding current and workpiece thickness in shielded metal arc welding (SMAW), with the objective of identifying the optimal combination that maximizes weld quality. The experiments were planned with the help of Taguchi’s L9 orthogonal array method in order to reduce experimental cost and time. The weld quality is optimized by determining the signal-to-noise ratios of weld penetration, tensile strength, impact strength, and microhardness for each experimental sample. As a result, 110 A welding current is obtained as the optimal SMAW parameter for a 5 mm thick MS IS 2062 Grade B plate. This optimized result has also achieved 394.78 N/mm2 tensile strength and 53 J of impact resistance for the respective specimen. Besides, research not only enhances understanding of the SMAW process but also offers practical implications for industries requiring high-performance welded joints in MS structures. Additionally, this study can assist upcoming researchers in optimizing any existing welding procedures.

Utilizing a dual nozzle system for notch generation in an underwater laser ablation process

The topic of munition in the sea and the associated dangers are becoming increasingly prominent due to ongoing corrosion and the corresponding release of toxic substances into the marine environment. In order to provide a safe defusing method for their salvage, the shell material needs to be partially weakened to about 1/3 of the material thickness. In this paper a dual nozzle system is utilized for optimized melt extraction, employing a Yb:YAG laser at a laser power of 2 kW on 10 mm thick mild steel samples under water. The process is investigated applying design of experiments methods regarding the depth of the notch and in particular the influence of the cutting gases oxygen, nitrogen and air. The impact of the weakening on the mechanical strength of the samples is determined by tensile tests.

Optimalisasi Perencanaan Dan Pengendalian Produksi Rak Palet Menggunakan Metode Cutting Plane

PT Atlantic Anugrah Metalindo is a manufacturing company that produces costumize products, steel door systems and fireproof doors. Currently PT Atlantic Anugrah Metalindo is producing 100 units of pallet rack manufacturing with customers from PT X so that proper material requirements planning is needed. The purpose of this research is to determine the material requirements of pallet racks optimally and efficiently. This research requires calculating the Bill of Materials (BOM) using the Cutting plane method and controlling the production process to run effectively and efficiently. Based on the calculations that have been carried out, the results show that for 2 mm thick mild steel material requirements, 6 sheets of plate are needed, 3 mm thick mild steel requires 173 sheets of plate, 3.6 mm thick mild steel requires 12 sheets of plate and 5 mm thick mild steel requires 12 sheets of plate. So that from these calculations PT Atlantic Anugrah Metalindo is expected to minimize the material requirements of pallet rack products.

Study of underwater plasma arc ignition and cutting process for surface nonconductive steel structures for offshore decommissioning

Plasma cutting is expected to play a significant role as a highly efficient thermal cutting method in offshore decommissioning. Offshore steel structures get covered with nonconductive substances such as rust, mud, and barnacles, which affect the ignition and maintenance of the plasma arcs. This study aimed to determine a suitable method for cutting steel structures covered with nonconductive substances. The entire process of the underwater plasma arc, including ignition, piercing, and cutting, was systematically studied experimentally. A multi-arc root state occurred during the ignition of the transferred plasma arc. In this state, the workpiece current is a significant signal for characterizing the piercing of nonconductive substances on the steel structure. The composite plasma arc exhibits better resistance to interference and a longer ignition distance. In lateral water flow, which was used to simulate ocean currents, the composite plasma arc pierced through 12-mm thick mild steel. Based on the experimental results, a novel cutting strategy was proposed, and a double-layered workpiece consisting of 8-mm thick cement and 12-mm thick mild steel was successfully cut. These findings may drive the application of plasma arc cutting in offshore decommissioning.

Experimental study of underwater plasma arc penetration parameters for oil wellheads

Dismantling abandoned oil wellheads is a central aspect of the decommissioning of production facilities. A wellhead consists of multiple layers of conductive oil casing nested with nonconductive cement rings. Plasma-arc cutting is expected to be used in abandoned wellhead demolition owing to its high processing efficiency for conductive materials. Currently, no reports are available on the operating parameters of plasma-arc cutting in oil wellhead dismantling. This study experimentally investigated the penetration parameters of an underwater plasma arc in abandoned wellheads. The stand-off distance, penetration angle, nozzle diameter, plasma arc current, and gas flow rate were considered as the main factors affecting the penetration effect. A composite workpiece consisting of 10 mm thick mild steel and 30 mm thick cement blocks was used to simulate a small segment of an oil wellhead. The penetration depth, removal volume, penetration specific energy, and nozzle loss were used as comprehensive evaluation indicators for optimizing the penetration parameters. Based on the results, the experimental phenomena during penetration were explained and recommended values of the underwater plasma arc processing parameters were provided. This study may advance the development of plasma arc cutting for the demolition of abandoned wellheads.

EFFECTS OF HOLDING TIME ON MICROSTRUCTURE AND SHEAR STRENGTH OF RESISTANCE SPOT-WELDED JOINTS BETWEEN MILD STEEL AND ALUMINUM WITH ZINC POWDER FILLER

This study aimed to determine effects of holding time on microstructure and shear strength of resistance spot-welded joints between mild steel and aluminum with zinc powder filler. The materials used are 0.9 mm thick mild steel, 1.2 mm thick 3000 series aluminum, and 200 mesh zinc powder. Welding parameters were selected as welding time of 0.5 seconds (s), electric currents of 8000 A and 9000 A, with holding time variations of 1 s, 3 s, and 5 s. Macro and scanning electron microscope (SEM) images follow ASTM E3-01, while ASME IX was used as tensile test standards. The macro images showed that holding time affected quality of the welded joints. Applying a longer holding time was able to reduce defects on the welded joints. SEM energy-dispersive X-ray spectroscopy (SEM-EDX) analysis exhibited that the holding time of 1 s produced a lack of density in the spot-welded joint, resulting in the existence of porosity. In contrast, increasing the holding time to 5 s gives a denser spot-welded joint with no defects found. The tensile test results showed that applying electric current of 8000 A, welding time of 0.5 s, and holding time of 1 s produced the joint with the weakest shear strength of 130 N. The highest joint shear strength of 790 N is obtained with the condition: electric current of 9000 A, welding time of 0.5 s, and holding time of 5 s.

Continuous Wave Fibre Laser Welding of AISI Stainless Steel SS 410 and Mild Steel

The main aim of this paper is to study laser welding of AISI stainless steel (SS) 410 and mild steel (MS) at different values of welding power, welding speed and frequency. The welding of dissimilar metals is most useful in structural, automobiles, furniture and decorative applications. But there is a difficulty in welding of mild steel and stainless steel due to the loss of carbon from mild steel and precipitation of chromium in stainless steel. Laser welding is best suitable process which is used to control the problems occurred during welding on base metals joints. A 2 kW continuous wave fibre laser welding machine was used to weld 2 mm thick stainless steel (SS) and mild steel (MS) plates. The photos of the welded joints were assessed and then tested to investigate the mechanical properties of the welded joints.

Analisis Pengujian Tarik dan Sebaran unsur pada Pengelasan Aluminium – Mild Steel menggunakan Metode Cold Metal

The technology that has been developed in recent years is the production of fusion welded plates between two different materials, for example, steel with other materials such as aluminum. Combining the two materials, aluminum and mild steel, will undoubtedly produce a material connection with good properties, for example, in a vehicle car frame. However, these two materials have different melting points, mild steel has a high melting point, and aluminum has a low melting point in the inner layer. This research aims to determine the welding results and the microstructure between aluminum plates and mild steel. The Cold Metal Transfer (CMT) welding process provides a potential method for joining dissimilar metals. In this study, various 4 mm thick aluminum alloys (Al 1100) were joined to 4 mm thick mild steel (SPHC) by CMT welding technology. It was concluded that combining aluminum alloys with mild steel using the cold metal transfer method was feasible. The optimum process variable for welding aluminum-mild steel dimensions 250 mm × 100 mm × 4 mm can be obtained with ER70S-6 wire, ArCO2 shielding gas, wire feed speed 13 m/min, and welding speed e8 mm/s.The tensile strength of the joint first increases and then decreases as the welding current increases, the highest tensile strength can reach 73.35 MPa.

A methodological approach to design a coil for localised high-frequency induction heating of flat plate

High-frequency induction heating (HFIH) is a quick heating technology, mostly used for localised surface treatment. The HFIH process has a portable RLC tank circuit consisting of a fixed size capacitor bank, load-matching transformer and a small size inductor coil. However, the work feasibility of small size inductor coil involves complexity in matching the resonant frequency between the RLC tank circuit and the high-frequency induction power source. Because the resonant frequency of the RLC tank circuit depends on the shape, size and configuration of the considered inductor coil. To address the issue, a numerical model-based approach is proposed herein to do the frequency matching for any coil configurations. Three different coil configurations such as co-direction, single-direction and opposite-direction current coils are considered in the simulation study to optimise their geometry and estimation of resonant frequencies. Based on the derived resonant frequency of the inductor coils, another coupled electromagnetic-thermal model is developed to get the thermal characteristics for a planar heating process of an 8 mm thick mild steel plate. After finding the optimal geometry of all coil configurations, the coils are fabricated and used in experimentation to verify the results of numerical models. It is found that the coil geometry has a significant effect on the resonant frequency and the heating characteristics. In addition, the current work emphasises a systematic approach to address the temperature non-uniformity that arises at the inlet and outlet positions of the workpiece in movable induction heating.

Blue laser welding of low thickness Ni-coated copper and mild steel for electric vehicle (EV) battery manufacturing

Modern advancements in blue lasers offer a promising alternative to conventional infrared laser welding of highly-reflective battery materials. In this study, a high-power blue laser system was used to weld the low thickness Ni-coated copper and mild steel used in 18650-type cylindrical cells. The effect of laser power on the penetration depth, interface width, and weld bead quality was studied. The weld microstructure was characterized by employing optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The mechanical performance of the welds was evaluated through peel testing and microhardness measurements. The results show that the penetration depth and weld width increased with laser power. Increasing the laser power to more than 1.3 kW resulted in a damaging effect on weld bead quality creating defects such as crack, under-fill, and distortion due to excessive heat input. Weld samples fractured in the heat-affected zone of Ni-coated copper during peel testing due to grain growth in copper. The maximum peel strength of 158.8 N was achieved for the 1.2 kW sample. The formation of a composite microstructure between Cu and Fe with a higher hardness than parent metals was observed inside the weld nugget. The hardness of this zone increased with the laser power due to an increase in the amount of Fe, reaching 185 HK for the 1.5 kW sample. By exposure to a corrosive environment, the peel strength drastically decreased and the failure occurred at the weld interface. For the 1.2 kW sample, the peel strength was reduced to around 57 N. The process initially developed for coupons of Ni-coated copper and mild steel was further tested on the positive and negative tabs of 18650-type cylindrical cells. The weld microstructure showed a lack of defects. However, due to varying thicknesses and associated heat sinks further process refinement is required for optimum joint quality.

Experiments on the kerf quality characteristic of mild steel while cutting with a high-power fiber laser

The laser cutting capacity has increased significantly in recent years, owing to the rising power of fiber lasers. Meanwhile, considerable emphasis is being paid to the quality of high-power laser cutting, particularly the issue of thick plate kerf taper. However, the mechanism by which the kerf taper is formed and the effect of process parameters on the kerf taper are rarely examined in detail when cutting a thick plate with a high-power fiber laser. The purpose of this study is to conduct a series of cutting tests using a 12-kW continuous-wave multimode ytterbium-doped fiber laser. The single factor experiment approach is utilized to determine the effect of each process parameter (stand-off distance, cutting speed, defocus amount, and auxiliary gas pressure) on the kerf taper of 25 mm thick mild steel. The Taguchi method of L25 orthogonal array is used to design the laser cutting experiment, and analysis of variance was used to determine the significant factor impacting the kerf taper. The regression model for the kerf taper was created using the experimental data. Further, the experimental study was used to analyze the mechanism by which the kerf taper of the thick plate was formed.

Design and fabrication of micro-plasma transferred wire arc additive manufacturing system

• This article reports an efforts in developing a micro-plasma transferred wire arc Directed Energy Deposition AM system. • The developed system can produce components with a layer thickness from 2 mm and surface roughness of 8-17 μm. • This article also describes the system capabilities as a cost effective alternative to laser DED systems. A wire-based Micro-Plasma Transferred Arc Additive Manufacturing (µ-PTAAM) setup is designed and fabricated. This system is developed with an objective to print alloy components with geometries on a laboratory scale under a controlled and safe environment. A Computerized Numerical Control based four-axis system with linear X, Y, Z, and a rotational movement (A) is used to manipulate heat source, wire feeder and the substrate. This system is capable of producing components with dimensions of 200 × 200×150 mm 3 with a weight of up to 50 kg using wire feedstock diameters ranging from 0.2 to 1.4 mm. Due to its low plasma energy and reasonable positioning control, it is possible to deposit thin bead (less than 2 mm) without significantly altering the substrate microstructure. In this paper, the capabilities of the fabricated setup are shown while depositing varying bead geometries using a 0.6 mm ER70S-6 filler wire on a 1.3 mm thick Dual Phase steel (DP 600) and 6 mm thick mild steel substrate. Deposited specimens exhibit defect-free beads with uniform profiles. This study demonstrates that the fabricated micro-plasma AM setup is a competitive alternative to other wire-based directed energy deposition systems.

Underwater laser ablation process using an Yb:YAG laser source for the weakening of mild steel sheets for the deflagration of hazardous substances

With an estimated amount of about 1.6 metric million tons, unexploded ordnances (UXO) in the German North and Baltic Sea pose a serious threat to the environment due to increasing corrosion. One way to allow safe salvage of the objects from the sea is to weaken them and then disarm them by low order detonation. This paper deals with the weakening by laser ablation, aiming for the introduction of ablation gaps with a depth of 2/3 the material thickness in 4 and 10 mm thick mild steel samples. An Yb:YAG laser source is used with a laser power of up to 2 kW in combination with a coaxial gas jet supplying the process zone with nitrogen to ensure a controllability of the process and the depth of the gap. The study is thus focused on achieving constant and predictable gap depths.

Evaluation of the sensitivity of higher order modes cluster (HOMC) guided waves to plate defects

Higher Order Modes Cluster (HOMC) guided waves are non-dispersive wave packets consisting of higher order Lamb wave modes. This paper investigates the effect of frequency and dominant mode(s) of an HOMC guided wave on its sensitivity to plate defects. The propagation of HOMC guided waves in a 10-mm thick mild steel plate is simulated by two-dimensional finite element model. The level of contribution of Lamb wave modes to the wave cluster is analyzed by using a two-dimensional Fast Fourier Transform (2D FFT) at various frequency-thickness products ranging from 15 to 35 MHz-mm. The normal stress profiles of the HOMC guided waves are plotted and used to show the changes in normal stress as a function of frequency-thickness product. The HOMC guided waves interactions with notches of 5%, 10%, 30% and 50% depths relative to the plate thickness are examined at various frequency-thickness products ranging from 15 to 35 MHz-mm. It is observed that the reflected energy from these notches decreases with increase in frequency-thickness product. Experimental measurements are also conducted on a similar plate. The experimental results are in line with simulations and confirm the changes observed in the reflection coefficient of notches at different frequency-thickness products.

The effects of undercut geometry on the static stress concentration factor of welds

Undercutting is a welding defect that appears as a groove in the base metal directly along the edges of the weld metal. It is inevitable in fillet and butt joints if improper welding parameters are used in the operation. It is a discontinuity in the welding that produces stress concentration and lowers the strength of the weld. The stress concentration factor of an undercut is due to the reinforcement angle, undercut width, undercut depth and undercut root radius. In this study, 20 mm thick mild steel plates were welded by automatic gas metal arc welding with the carbon dioxide (CO2) shielding gas process. A single-V butt joint was obtained after welding. Before welding, 30° groove angles were obtained by milling on the longitudinal side of each workpiece. Two plates were welded with several passes. After welding, the weldment was tested with a radiographic non-destructive testing process. A defect-free weldment was obtained. Then, standard tensile test samples were machined from the weldment. A groove was drilled in the heat-affected zone, adjacent to the weld metal boundary on every tensile test sample. Each groove resembled an undercut. The length, root radius and depth of grooves were varied. Then, the samples were broken on a tensile test machine. From the test results, the static stress concentration factor of each groove was calculated. The effects of groove geometry on stress concentration factors were determined.

Experimental Investigation of the Effects of Irradiating Schemes in Laser Tube Bending Process

The laser tube bending process (LTBP) process is a thermal non-contact process for bending tubes with less springback and less thinning of the tube. In this paper, the laser tube bending process will be studied experimentally. The length of irradiation and irradiation scheme are two main affecting process parameters in the LTBP process. For this purpose, different samples according to two main irradiation schemes (Circular irradiating scheme (CIS) and axial irradiating scheme (AIS)) and different lengths of laser beam irradiation (from 4.7 to 28.2 mm) are fabricated. The main bending angle of laser-bent tube, lateral bending angle, ovality, and thickness variations is measured experimentally, and the effects of the irradiating scheme and the length of irradiation are investigated. An 18 mm diameter, 1 mm thick mild steel tube was bent with 1100 Watts laser beam. The results show that for both irradiating schemes, by increasing the irradiating length of the main and lateral bending angle, the ovality and thickness variation ratio of the bent tube are increased. In addition, for a similar irradiating length, the main bending angle with AIS is considerably higher than CIS. The lateral bending angle by AIS is much less than the lateral bending angle with CIS. The results demonstrate that the ovality percentage and the thickness variation ratio for the laser-bent tube obtained by CIS are much more than the values associated with by AIS laser-bent tube.

A Low-Frequency Eddy Current Probe Based on Miniature Fluxgate Array for Defect Evaluation in Steel Components

Detecting defects in high-permeability steel components can be challenging when using the eddy current technique. This is due to the strong magnetization signal that is simultaneously generated along with the eddy current signal. To minimize the regions of the induced eddy current and its detection, an eddy current probe based on an array of miniature fluxgate sensors (DRV425, Texas Instrument, USA) and axial inductors was proposed and fabricated in the study. The fluxgate sensors were arranged in two layers, and the sensors were sandwiched between two layers of inductors. The output signals from the fluxgate array were sampled to obtain a differential signal of the eddy current intensity and direction. A phase-sensitive detection technique was implemented to isolate the strong magnetization signal from the detected eddy current signal and utilized to characterize artificial slits with varying depths. The developed probe successfully characterized both the vertically and horizontally oriented slits with depths from 2 to 10 mm on a 12 mm thick mild steel plate. A better sensitivity was notable in the evaluation of the vertical slits where the vertical slits would increase the eddy current intensity in contrast to the horizontal slits around the slits. It was shown that the eddy current’s distribution map obtained from the developed probe could be used to reveal the physical dimension of the slit.

Non-contact in-process ultrasonic screening of thin fusion welded joints

Joining of metal structures, or welding, plays a critical role in our modern world, where safety critical welds of thin sheet metals are used in pipework, nuclear cannisters and aircraft ducting among others. A potential failure in such welds could prove to be catastrophic, hence the need for thorough inspection and testing. With the ever-increasing automation of welding operations, manually deployed Non-destructive Evaluation (NDE) has become a major bottleneck in the supply chain. This paper introduces for the first time, non-contact gas-coupled ultrasonic sensors deployed in-process during weld deposition, for screening of weld penetration directly at the point of manufacture. 3 mm thick mild steel plates were butt-welded together using Gas Tungsten Arc Welding (GTAW) while non-contact air-coupled ultrasonic transducers, generating surface guided Lamb waves, performed inspection screening of the weld seam. Optimised Signal-to-Noise Ratio (SNR) was achieved through a customised acoustic matching layer, low-noise amplifiers and real-time signal processing. By performing multiple trials at varying levels of welding input power (0.59 kJ/mm to 1.03 kJ/mm), it was demonstrated that the amplitude of the through transmission A0 Lamb wave is correlated to the Weld Penetration Depth (WPD) and can be used for on-line weld quality screening. Advantages of the outlined method include higher production rates, reduced levels of scrap and higher production quality in regards to thin metal sheet welded components.

Diode laser assisted oxygen cutting of thick mild steel with off-axis beam delivery

Laser assisted oxygen cutting (LASOX) of 20–40 mm thick mild carbon steel is performed using fiber-coupled diode lasers with a combined optical power of 400 W. The experimental cutting head assembly is designed to deliver the laser beam off-axis to the cutting oxygen jet. Under this non-standard beam delivery conditions, the top edge of the cut may suffer from an excessive melting, overheated by the inclined laser beam. We propose a strategy in order to diminish the top edge melting defect and demonstrate that high quality cuts can be obtained in 20 mm thick workpieces, and lower quality separation of up to 40 mm steel thickness. The experimental results demonstrate the potential of high-power diode sources in the LASOX cutting method, and the ability of relatively low power, compact and lightweight diode-based systems to cut thick sections of mild steel.

Parametric Study of Pulse Arc Welding (PAW) and Laser Beam Welding (LBW) Techniques for Electrical Vehicle Battery Cells

Electrical vehicles (EV) offer the automotive industry the potential to meet future emission targets by developing large battery systems. These battery systems require several thousand single battery cells to be connected together. The battery cells are complex assemblies of dissimilar materials with very low thicknesses, which presents a significant challenge during the joining process, especially welding. We have investigated the performance of laser beam welding (LBW), as well as pulsed arc welding (PAW) for joining 0.3mm thickness nickel coated copper to 0.7mm thickness mild steel. The parametric study for good quality lap welds based on high tensile strength, was performed. The weld microstructure was investigated using optical, as well as scanning electron microscopy (SEM). The mechanical performance of the weld samples was characterized through tensile testing and micro hardness measurements to establish the microstructure property relationship. The maximum tensile strength measured for specified weld geometries was 660N for LBW and 496N for PAW. A significant increase in the hardness was measured in the weld nugget due to the formation of Cu-Fe composite microstructure