AISI 1015低碳鋼與AISI 304不鏽鋼異質銲件於氯化鈉/硫酸納混和鹽之熱腐蝕

Metal Inert Gas welding (MIG) is a widely used welding method for mild steel (low carbon steel) in industry due to its high weld quality, good penetration and comparatively low investment. It is an arc welding process wherein coalescence is produced by heating the job with an electrical arc struck between a filler rod and the job. A Shielding gas (argon, carbon dioxide) is used to avoid atmospheric contamination of the molten weld pool. A filler material is added for joining the work piece by MIG welding. Many researchers investigated on different welding process parameters on mechanical & microstructural characteristics. Some researchers used the welding speed, welding current welding voltage, number of welding passes & work peace thickness for stainless steel, naval grade steel & aluminum. But the shielding gas flow rate & gas mixture also important factor which affects mechanical properties of mild steel. For this study, process parameters such as welding current, gas flow rate and gas combination used in the range 170-210A, 13-17 Lit/min & 0-100 % of CO2 respectively. The material used E-250 grade mild steel with 12 mm thickness. The effect of the welding parameter is investigated by designing the experiments using central composite matrix. Using the data generated by the experimentation, an empirical relation is obtained for tensile strength. The optimum value of tensile strength 356 N/mm 2 is observed at 190A welding current, 15 Lit/min gas flow rate & 50% CO2+50% Argon gas combination. Index Terms —Co2 Welding, v-butt Welds, welding current, gas flow rate, Gas combination, Tensile strength.

Growth of poly(2,5-dimethoxyaniline) coatings on low carbon steel

Handles welded to the top cover plate of a chemical-plant downcomer broke at the welds when the handles were used to lift the cover. The handles were fabricated of low-carbon steel rod; the cover was of type 502 stainless steel plate. The attachment welds were made with type 347 stainless steel filler metal to form a fillet between the handle and the cover. The structure was found to contain a zone of brittle martensite in the portion of the weld adjacent to the low-carbon steel handle; fracture had occurred in this zone. The brittle martensite layer in the weld was the result of using too large a welding rod and too much heat input, melting of the low-carbon steel handle, which diluted the austenitic stainless steel filler metal and formed martensitic steel in the weld zone. Because it was impractical to preheat and postheat the type 502 stainless steel cover plate, the low-carbon steel handle was welded to low-carbon steel plate, using low-carbon steel electrodes. This plate was then welded to the type 502 stainless steel plate with type 310 stainless steel electrodes. This design produced a large weld section over which the load was distributed.

In order to control the required surface quality, generally it is vital to have the choice of optimized cutting factors in various industrial machining operations. The trait of surface finish is a vital concern for most of the turned parts in an industry. The present research work is focused on the optimization of cutting process parameters (depth of cut, feed rate, spindle speed) in wet turning of High Carbon High Chromium Steel (2.2% C) having hardness 50+2 HRC. Therefore turning operations were performed on High Carbon High Chromium Steel by carbide P-30 cutting tool in wet condition and the combination of the optimal levels of the parameters was obtained. Analysis of Variance (ANOVA) and SN (Signal-to-Noise) ratio were implemented to analyze the performance characteristics in wet turning operation. The results of the analysis show that none of the factors was found to be significant. Taguchi method showed that spindle speed contributed the highest effect on the surface roughness followed by depth of cut and feed rate while turning High Carbon High Chromium Steel by carbide cutting tool in wet turning. The useful results obtained by this research can be the eye openers for other similar type of future research works.

In recent years, important steel structures of high-rise buildings such as the box columns required high toughness of welded joints considering the shockproof against the large-scale earthquake. In Japan, there are some specifications that demand Charpy impact energy more than 70 J at 0 °C in any welded joints. However in high heat input electro-slag welding, the microstructure of the weld metal becomes very coarse and weld metal toughness is remarkably deteriorated. In this paper, authors tried to form fully acicular ferrite microstructure in the weld metal of high heat input electro-slag welding to improve the weld metal toughness. High heat input (approximately 100 kJ/mm) electro-slag welding was carried out in the 60 mm thickness steel plate joint. Applying high Ti bearing welding wire and low basicity welding flux provided the weld metal with acicular ferrite microstructure, because large amounts of Ti containing oxide inclusions which were known as effective nucleation sites for acicular ferrite formations were dispersed in the weld metal. B addition to the weld metal suppressed the formation of coarse grain boundary ferrite when B/N ratio in the weld metal ranged between 0.5 and 0.8. When B/N ratio in the weld metal exceeded 0.8, the weld metal toughness was deteriorated due to an increase of M-A constituent. Consequently it was possible that fully acicular ferrite microstructure was formed in the weld metal of high heat input electro-slag welding and achieved the excellent weld metal toughness (vE0 > 100 J).

The effect of solidification on the formation and growth of inclusions in low carbon steel welds

Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering material and weld metal were Inconel 82. In another type, buttering material and weld metal were Inconel 182. In case of Inconel 82, method of welding was GTAW. For Inconel 182, welding was done by SMAW technique. For one set of each joints after buttering, stress relief annealing was done at ~923 K (650 °C) for 90 minutes before further joining with weld metal. Microstructural investigation and sub-size in situ tensile testing in scanning electron microscope were carried out for buttered–welded and buttered–stress relieved–welded specimens. Adjacent to fusion boundary, heat-affected zone of low alloy steel consisted of ferrite–pearlite phase combination. Immediately after fusion boundary in low alloy steel side, there was increase in matrix grain size. Same trend was observed in the region of austenitic stainless steel that was close to fusion boundary between weld metal-stainless steel. Close to interface between low alloy steel-buttering material, the region contained martensite, Type-I boundary and Type-II boundary. Peak hardness was obtained close to fusion boundary between low alloy steel and buttering material. In this respect, a minimum hardness was observed within buttering material. The peak hardness was shifted toward buttering material after stress relief annealing. During tensile testing no deformation occurred within low alloy steel and failure was completely through buttering material. Crack initiated near fusion boundary between low alloy steel-buttering material for welded specimens and the same shifted away from fusion boundary for stress relieved annealed specimens. This observation was at par with the characteristics of microhardness profile. In as welded condition, joints fabricated with Inconel 82 exhibited superior bond strength than the weld produced with Inconel 182. Stress relief annealing reduced the strength of transition joints and the reduction was maximum for specimen welded with Inconel 82.

This paper outlines the unique role of Crateva adansonii (CA) leaf extract on low carbon steel in corrosive media. The defensive ability of Crateva adansonii extract was evaluated by gravimetric and gasometric techniques. The result of the experiment indicated that extract of Crateva adansonii exhibit perfectly well on the steel due photochemical species containing in the inhibitive extract thereby blocking both the anodic and cathodic site. The mixed Inhibitive effect of Crateva adansonii were investigated by the kinetic state. The adsorption studies of CA leaf extract obeyed the Langmuir, Freundlich, temkin isotherm but best fitted into Langmuir adsorption isotherm which characterised by physisorption. The range of Ea values (from 46.09 kJ/mol to 60.58 kJ / mol) in the presence of the extract being higher than the free solution. Which suggests strong physical adsorption (physisorption).

Plasma electrolytic oxidation (PEO) coatings were prepared on low carbon steel from electrolytes with different silicate concentrations. The microstructure, elemental and phase compositions of the PEO coatings were analyzed by scanning electron microscope, energy-dispersive spectrometer, and x-ray diffraction, respectively. The adhesion of PEO coatings with low carbon steel substrate was qualitatively examined by thermal shock tests. The tribological properties were evaluated by a reciprocating tribometer sliding against a Si3N4 ceramic ball. The corrosion behaviors of PEO coatings were investigated in 3.5 wt.% NaCl solution by electrochemical impedance spectra and potentiodynamic polarization. Results indicated that all the PEO coatings were comprised of amorphous SiO2 and Fe-containing oxides; however, the silicate concentration in electrolyte showed significant influence on the growth and the performance of PEO coatings. The PEO coating prepared from the electrolyte with silicate concentration of 30 g/L had the highest Fe content because the substrate was more readily oxidized and showed a dense structure, resulting in the best comprehensive performance of adhesion, wear resistance, and corrosion resistance.

Low carbon steel is widely used in oil and gas applications. In this research, multilayers of Nickel (Ni) and Copper (Cu) were deposited on a low carbon steel substrate using the electroplating process (ELP). Initially, a layer of Ni was coated, followed by a layer of Cu. ELP was implemented using water bath containing (300 g/l) of NiSO4.6H2O, (30 g/l) of (NiCl2.6H2O), (40 g/l) of H3BO3 and (30 g/l) of (NaCN), (30 g/l) of (CuCN), (10 g/l) of (NaOH.6H2O). First bath parameters were temperature is (59 - 60 °C), current density in the range of (3-5 A/dcm2), voltage was holed at (8 V) for Ni, and temperature was between (50-51 °C), current density in the range of (1-2 A/dcm2), voltage was holed at (4 V), while the plating time (10 minutes) for both Ni and Cu. The results refer to Ni, Cu, and Ni & Cu ELP thicknesses 3, 4.77 and 6.75 μm respectively. Metallurgical tests were achieve including the micro hardness of ELP, Vickers micro hardness results showed improvement in hardness values compared, with steel substrate, and in the presence of Ni, Cu, Ni+Cu layers, 322, 581, 479, and 562 Hv respectively. The roughness was measured using surface roughness measurement device. The average surface roughness (Ra) depicted satisfying values as a result of Ni layer coating, which gave uniform surface distribution with Ra 0.363 μm. X-ray diffraction (XRD) test examinations serve as strong evidence for the presence of Ni and Cu in the internal and external finish layers, respectively. Corrosion examinations were carried out in seawater solution (3.5 g NaCl) the corrosion behavior tends to be more resistance, with layers of Ni, and Cu in sea water environment, which is considered an important criterion to increase the part life.

The aim of this study is to determine the effect of variations in welding current strength on the tensile strength of ABREX 400 steel weld joints. The results of this study are expected to give contribution toward the world of metal welding, especially low carbon steel metal welding which will later be beneficial for the development of the metal industry and technology. The method used in this research was the experimental method. In addition, the process of welding the material used SMAW welding and the type of seam V connection and the variations in the current strength used are 90 A, 100 A, and 110 A. The specimen used was a TRS 400 low carbon steel plate with a thickness of 10 mm and the electrode used was the E7018 electrode Ø 3.2 mm. The standard specimen used was ASTM-8 and the test was carried out using the Universal Testing Machine tensile test device. As a result, the research showed that the tensile strength at a current of 90 A was 588.91 N / mm2, a current of 100 A was 570.56 N / mm2, and a current of 100 A was 545.17 N / mm2. Based on the results of the research, it can be concluded that welding using a current strength of 90 A produces the highest tensile strength value, namely 588.91 N / mm2 compared to currents of 100 A and 110 A.

The complex interaction between laser and material in Laser Wire Direct Energy Deposition (LW-DED) Additive Manufacturing (AM) benefits from process monitoring methods to ensure process stability and final part quality. Understanding the relationship between process parameters and melt pool geometrical characteristics can be used to effectively monitor and in-process control the process, as the melt pool geometrical characteristics serve as crucial indicators of process stability and quality.This study presents a novel in-situ monitoring approach for LW-DED, utilizing process images for melt pool segmentation, melt pool geometrical characteristics estimation, process stability assessment, and bead geometry prediction. The segmentation of melt pool objects was successfully accomplished using Convolutional Neural Networks (CNN)-based models, enabling the prediction of essential parameters such as melt pool area, height, width, center of area, and the center point of the bounding box enclosing the melt pool. Multiple models were compared regarding the accuracy and processing speed using a controlled central composite design and random experiments. We used an Inconel alloy 625 wire and two distinct substrate materials for deposition, a coaxial laser welding head with a 3 kW fiber laser, and an off-axis welding camera for monitoring.Among the CNN architectures evaluated, YOLOv8l demonstrated superior accuracy with mean Average Precision (mAP) values of 0.925 and 0.853 for Stainless Steel (SS) and low carbon steel (S355) substrates, respectively. Additionally, YOLOv8s exhibited a notable processing speed of over 114 frames per second, which indicates its suitability for real-time process control. Furthermore, the results indicate a significant correlation between process parameters and melt pool geometry variables. Notably, a clear correlation was established between melt pool characteristics and bead geometries obtained through microscopic examinations, including penetration depth and heat-affected zone. The analysis revealed a significant correlation for the bead area and width parameters. In relation to the bead height, while the correlation exhibited a lower magnitude compared to bead area and width, it remained responsive. In addition, the tensor masks derived from the developed models have proven to be highly effective in accurately predicting bead geometries.The results demonstrate the effectiveness of YOLO-based algorithms for detecting and segmenting the melt pool. Statistical analysis confirms the significance of stabilized process data and the accuracy of melt pool geometric models. We demonstrate that integrating advanced monitoring and control techniques using artificial intelligence methods like CNN can facilitate process stability and quality control.

In this investigation, the microstructure changes of 0.25% low carbon steel, which is hardfaced with high chromium white iron by a semiautomatic welding process was studied using OM, SEM and EDX analysis. Mechanical properties, such as hardness and wear rates, were also investigated. Four groups of samples were used in the study. The first group of samples was low carbon steel without any surface treatment. The second, third, and fourth groups of samples were selected from several hard-faced low carbon steel pieces with 3.0, 3.4 and 3.8 % of chromium contents in their hard-faced surface respectively. SEM analysis results show that the microstructure of the surface treated samples consist of a small amount of ferrite and a large amount of pearlite. EDS test shows that the chromium contents of both ferrite and pearlite have increased significantly. Increasing pearlite amounts and increasing chromium concentrations in every phase seem to increase the hardness from 280 to 495 HV30. Chromium content was increased in both pearlite and ferrite. This increase causes the phase’s hardness to be increased. Also, there is a trace of М7С type carbides that appeared in hardfaced surface with higher chromium content.

Microstructure and Mechanical Property of Resistance Spot Welded Joint of Dissimilar Steels of TRIP 980 High Strength Steel and SPCC Low Carbon Steel

Basic-coated electrodes are preferred for welding medium and thick section austenitic stainless steels because these consumables provide weld metal with high toughness, quality and resistance to cracking. Strength and toughness of weld metals depend on their microstructure, which is determined by the concentration of various alloying elements, impurities as well as the welding thermal cycle. However, in basic-coated electrodes, optimisation of flux formulation is complex because slag detachability is a problem with basic fluxes that confer high weld metal toughness. This study investigates the effects of systematically varying the cerium oxide content in the flux coating used in a basic-coated austenitic stainless steel electrode for shielded metal arc welding (SMAW). SMAW process with 16-mm-thick stainless steel plates and in-house-developed electrodes of 3.15 mm in size added with different levels of cerium oxides in the flux coating was used to prepare the weld pads. The weld pads were qualified with radiography examination as per ASME section III class I components. Tensile specimens were prepared as per American Society for Testing and Materials (ASTM) E8 and tensile properties were evaluated at both ambient and service temperatures. Charpy ‘U’ notch impact specimens were prepared in the as-welded and fully sensitized conditions (1,023 K/100 h) and the impact tests were carried out as per ASTM E23. Variation in the weld metal chemistry, mechanical properties, oxygen content, inclusion morphology and microstructure with cerium oxide content in the flux was examined. The results indicated that at an optimal level of cerium oxide addition in the flux coating played a major role in reducing sulphur and oxygen content; subsequently, it improved the mechanical properties of the weld metal. In this paper, the results of detailed studies and analysis were discussed on microstructures using optical and scanning electron microscope carried out on the weld metals produced with different levels of cerium oxide in the flux.