Structural Carbon Steel Research Articles

Analysis of the mechanical properties and wear characteristics of nail teeth based on sowing layer residual film recovery machine

This study aims to address the problem of the arc-shaped nail tooth, a key component in pre-sowing film recovery machines, being prone to wear and fracture deformation. To determine its wear and damage mechanism, this paper uses chlorinated butyl rubber and soil particles to simulate the wear environment of the nail tooth. Carbon structural steel (45 steel), spring steel (60Si2Mn), and alloy structural steel (40Cr) are selected for performing friction wear tests and mechanical property analysis. Detailed failure analysis is performed using scanning electron microscopy (SEM), three-dimensional (3D) morphology, and energy-dispersive X-ray spectroscopy (EDS). The results demonstrate that abrasive wear occurred in all samples. #45 steel and 40Cr showed significant plastic spalling during the wear process. 60Si2Mn has the lowest surface roughness and wear depth at 0.5709 and 2.412 µm, respectively. By combining the micromorphological characterization and element content changes of these samples after wear, the results demonstrate that the wear and oxidation of 40Cr and #45 steel are more severe than 60Si2Mn. “River-pattern” fracture and tear ridges were observed in the 40Cr fracture surface, indicating quasi-cleavage fracture characteristics. 60Si2Mn exhibits multiple ductile dimples, an apparent ductile fracture mechanism; moreover, #45 steel exhibits good plasticity with no observed fracture. Based on comprehensive analysis, 60Si2Mn has excellent wear and plastic deformation resistance. This study provides a reference for selecting the material for the film-picking nail teeth in mulching film recycling machines.

Temperature Measurement during Abrasive Water Jet Machining (AWJM).

This study was undertaken to look for confirmation that heat transfer induced by abrasive water jet machining (AWJM) affects the microstructure of the material cut. The structure of S235JR carbon steel used in the experiments was reported to change locally in the jet impact zone due to the high concentration of energy generated during cutting with the abrasive water jet. It is assumed that some of the energy is transferred into the material in the form of heat. This is particularly true for materials of considerable thickness with a high thermal conductivity coefficient when cutting is performed at low speeds or with high abrasive consumption. The literature on the subject suggests that in AWJM there is little or no thermal energy effect on the microstructure of the material cut. The research described here involved the measurement of the cutting temperature with thermocouples placed at four different distances from the edge. The distances were measured using computed tomography inspection. The thermocouples used in the tests were capable of detecting temperatures of up to 100 °C. Locally, temperatures at the edge may reach much higher values. The results of the X-ray diffraction qualitative phase analysis reveal that locally the temperatures may be much higher than the eutectoid temperature. Phase changes occurred along the edge since austenite was observed. This suggests that the temperature in the jet impact zone was much higher than the eutectoid temperature. Optical microscopy was also employed to study the material microstructure. Finally, the material nanohardness was determined.

Influence of Pre-Tinning Process on Coating Morphology and Interface Structure of Low Carbon Steel Dipped in Molten 6061 Al Alloy

Pre-treated low carbon steel specimens with flux or flux + tin mixture were coated by hot-dip aluminizing process. Al alloy (6061) was melted and hold at 750 °C. Fluxed and pre-tinned low carbon steel samples were dipped in a molten bath for time intervals of 0.5, 1, 2.5 and 3.5 min. Applying double coating processes via tinning-aluminizing techniques facilitated the formation of Fe-Al intermetallic interface and increasing the thickness of homogenous coating layer over the substrate material. The presence of Sn facilitates to great extent the formation of a better interlayer-free bond of residual flux and/or oxides. The fluxed–dipped steel substrates have inhomogeneous distribution of Al alloy coating as well as an interface with residual flux and oxides for dipping time up to 2.5 min. A homogenous distribution with good thickness morphology of the Al alloy coating and homogeneous thin intermetallic interface was achieved for tinned steel substrate at all applied dipping times. The comparison between the pre-tinning and pre-fluxing processes on steel substrates showed a significant effect of tinning over fluxing treatment acting on the thickness layer of Al-coating and interface using a short time dipping. For dipping time up to 2.5 min, the hardness of pre-tinning substrates is greater than that of fluxed ones due to the presence of residual flux and void interface in fluxed steel.

Implementation of Exceptional Microstructures and Mechanical Properties of Structural Carbon Steel Tubes by Friction Welding

In this study, friction welding was applied to carbon steel tubes at a high speed condition to achieve an eco-friendly welding process and a superior mechanical performance. Friction welding is a very efficient process for joining materials without defects, especially with joint rods or tubes. For this study, cold drawn carbon steel tubes (AISI 1020) were introduced as the base material and successfully joined by friction welding. Friction welding was performed with parameters of a burn-off length (1, 2 and 5 mm). In order to analyze the welds, the electron backscattering diffraction method was introduced and observed the grain boundary characteristic distributions such as grain size, shape and orientation. To evaluate the relationship between the mechanical properties and microstructure, Vickers microhardness and tensile tests were introduced. As a result, the yield strength of the welds significantly increased relative to the base material at all conditions, and which derived from the microstructure development like a refined acicular ferrite grains through the dynamic recrystallization during the welding. Consequently, we suggest the optimum conditions of the friction welding with the interdependence of the microstructures and mechanical properties in this study. This demonstration substantially offers the possibility of an eco-friendly environment and superior tube welding quality without any defect and harmful gases at the high speed welding process as well as at the lowest cost. This technology can be extended to mass production processes with exceptional benefits for various industries.

Cathodic Protection of Complex Carbon Steel Structures in Seawater

Cathodic protection efficiency of complex carbon steel structures in confined seawater environment was studied using a specific experimental device. Schematically, this device consisted of a Plexiglas matrix, crossed by a channel 50 cm long, 5 mm deep, 1.5 to 5 cm wide, which moreover included four bends at 90°. Seawater flowed continuously inside the channel over 12 steel coupons embedded in the Plexiglas matrix. Cathodic protection was applied at a constant potential of −1060 mV vs. Ag/AgCl-seawater with respect to a reference electrode located outside the channel, at the seawater flow entry. The potential of four selected coupons was monitored over time via a microelectrode set close to each coupon. It varied significantly with the distance separating the coupons from the channel entry. At the end of the 3.5-month experiment, a polarization curve was acquired. The residual corrosion rate under cathodic protection was estimated via the extrapolation of the anodic Tafel line. It varied from <1 µm yr−1 to 16 µm yr−1, depending on the potential reached by the coupon (between −900 and −1040 mV vs. Ag/AgCl-seawater) at the end of the experiment and on the properties of the calcareous deposit formed on the steel surface.

Formation of smooth anodic nanoporous iron oxide film for enhancing photocathodic protection on plain carbon steel

It is essential to fabricate smooth nanoporous iron oxide film with fewer defects on plain carbon steel (CS) to improve photocathodic protection of the film in corrosive media. For that, high temperature annealing heat treatment was chosen to manipulate the metallographic structure of CS in the muffle furnace at 900 °C with the duration of 30 min. Following that, the annealed CS was anodized in a mixture of aqueous ammonium fluoride solution and ethylene glycol to fabricate smooth nanoporous oxide film on CS. Finally, as-anodized oxide film was calcinated at 450 °C for 4 h in nitrogen atmosphere to form crystalline iron oxide film. Several electrochemical techniques were applied to analyze the photoelectron property and photocathodic protection performance of nanoporous iron oxide films. On the contrary, rough nanoporous iron oxide film with more striking defects was fabricated on untreated (no annealed) CS by using the same anodization and calcination processes. The results show that the metallographic structure of annealed CS behaved more uniform ferrite grains and fewer pearlite precipitate than untreated CS. Thereby, a smooth nanoporous iron oxide film with fewer defects formed on annealed CS. On the contrary, a rough nanoporous iron oxide film with more defects, such as dimples and cracks were fabricated on untreated CS. Both of iron oxide films were composed of hematite as the main phase and magnetite as the secondary phase. Therefore, the smooth iron oxide film displayed comparatively better conductivity and higher donor density under the condition of illumination than the rough film. On account of those, smooth film exhibits comparatively higher anodic and cathodic reaction activities and more excellent and stable photocathodic protection to the counter.

Вплив швидкості охолодження та перегріву вище лінії ліквідусу на формування структурних складових

In the paper, the comparative analysis of the process of forming a cast structure of carbon steel after termination of its crystallization in continuous cast steel billet with diameter of 450 mm and overheating of steel to 50° C and 150° C above the liquidus line, and further pouring into wedge-shaped molds, is performed. The microstructure of the skin zone after continuous casting of steel with maximum cooling rate of 106 °С/min consists of dendrites, which have branches of the first and second order, indicating their formation from the melt. When etching the surface of the specimens with solution of nitric acid, the microstructure of the skin zone was represented by ferrite, perlite with separate areas of martensite. The formation of ferrite, perlite and bainite areas was observed at a distance of 0.5 ingot radius and in the central part of the samples, and separate areas of bainite and perlite were observed in the central part of the ingot. Upon further cooling of steels below the temperature of Ar3, the formation of excess ferrite along the boundaries of austenitic grains occurs. Overheating of steels to 50° C and 150° C above the liquidus line gives rise to the formation of a more homogeneous structure. Non-metallic inclusions formed in steel do not exceed 1 point according to DSTU 4967:2015and are not the centres of crystallization – they are observed in perlite grains. There is the formation of separate inclusions of phases located in the perlite grain, which contributes to the finely dispersed hardening of steel. Increasing the overheating temperature leads to the formation of more finely divided inclusions and to the formation of a more homogeneous structure. After overheating to 50° C in the middle part of the wedge (cooling rate of 102-103 ° C/min) no ferrite formation is observed. At all overheating temperatures, perlite has a fine differentiation, but increasing in the overheating temperature above the liquidus line enhances the dispersion of both individual inclusions and perlite. Keywords: carbon steel, continuous cast steel billet, hardening, cooling rate, overheating of steels above the liquidus line.

STUDY OF THE INFLUENCE OF THE Si/Mn CONTENT RATIO ON THE DENDRITIC STRUCTURE OF STEELS FOR RAILWAY AXLES

Purpose. Investigation of the effect of different total concentration and ratio of Si and Mn content on the dendritic structure and segregation inhomogeneity of cast carbon steel and its transformation after hot plastic deformation.
 Methods of research. To determine the effect of the content of Si and Mn, experimental ingots with a variable chemical composition within the grade were made for three steel grades used for the manufacture of railway axles – grade OS according to DSTU 31334, F according to AAR M 101 and EA1N according to EN 13261. To determine the dendritic structure microstructural analysis was used after etching in sodium picrate.
 Results. A comparative analysis of the microstructure of the experimental heats of steels with a variable chemical composition has been carried out. The ratio of content in steel Si and Mn in the cast state and after deformation is established. A significant effect of the total deoxidation in steel on the formation of microhardness inhomogeneity over the cross section of a carbon steel ingot and microinhomogeneity of the structure of individual sections is shown. It was found that after deformation, the central zones turned out to be the most worked out (especially for steel with a chemical composition within the EA1N grade, characterized by an increased content of Mn).
 Scientific novelty. The study of the influence of fluctuations in the content of the basic elements of carbon steel leads to the development of ideas about the formation of a dendritic structure and segregation heterogeneity in railway axle steels.
 Рractical value. Knowledge of the principles of segregation formation is necessary to determine further modes of deformation and heat treatment not only for continuously cast billets or ingots, but also for final products.

Experimental Study on the Influence of Particle Diameter, Mass Concentration, and Impeller Material on the Wear Performance of Solid–Liquid Two-Phase Centrifugal Pump Blade

A centrifugal pump is an important solid–liquid mixture conveying machinery, which is widely used in mineral mining, water conservancy engineering, and other fields. Solid particles will wear the impeller of the centrifugal pump in the process of transportation, resulting in lower service life of the impeller, especially in the transportation of a high concentration of solid particles. Many scholars use numerical simulation to study the wear of centrifugal pumps, but few efforts have been made in the wear experiment. In this study, the effect of three factors, namely, diameter of solid particles, mass concentration of particles, and material of impellers on the wear of a solid–liquid two-phase centrifugal pump was studied by the wear experiment. The solid particles are SiO2 with irregular shapes, and the diameter ranges are 0.125–0.212 mm, 0.212–0.425 mm, and 0.425–0.710 mm. The mass concentration of solid particles is 15%, 20%, and 30%. The material of impellers is carbon structural steel (Q235), gray cast iron (HT200), and low-alloy high-strength steel (16 Mn). The amount of wear is determined by measuring the thickness of the impeller material before and after wear experiments. The wear morphology of the impeller was observed by using a digital microscope. The results showed that the wear mainly concentrated on the middle and trailing edges of the blade. Impellers of different materials suffer different wear forms, among which the impeller made of HT200 has the best erosion resistance. The increase of solid mass concentration will aggravate the wear of the impeller. The change of particle diameters also has a great influence on impeller wear.

Особенности наложения ультразвуковых колебаний в процессе сварки

Introduction. The main problem in obtaining welded joints is the nonuniform heating of the joint zone, which leads to differences in the structure and properties of the weld metal and the base metal. One of the ways to intensify the welding process is the use of ultrasonic vibrations. As a result of the analysis of methods for introducing ultrasonic vibrations into the melting zone, a method of superimposing vibrations on the elements to be welded was chosen for experimental studies. This method makes it possible to influence the welded elements throughout the entire welding cycle from the melt bath to complete crystallization of the metal. Methods. Experimental studies were carried out on plates made of carbon structural steel St3 (ASTM A568M, AISI 1017, DIN 17100) and aluminum deformable non-hardened alloy AMg4 (EN AW-5086, AW-AL Mg4, 5086). As a source of oscillations, a rod magnetostrictive oscillatory system was used, the end of which was rigidly fixed on one of the welded plates. To determine the places of application of the oscillation source and the welding zone, a calculation method is proposed based on the equality of the resonant frequencies of the used oscillatory system and the natural frequency of bending vibrations of the welding component. It is shown that the optimal places for the application of vibrations and welding will be the antinodes of oscillations, which have the maximum amplitude. Welds were obtained by the method of semi-automatic gas metal arc welding. Results and Discussion. Microstructural study of obtained samples showed a significant decrease in the proportion of dendritic segregation. The changes in the structure are the result of the effects that occur in the liquid melt when ultrasonic vibrations are introduced. The main effects are sound pressure, cavitation and acoustical streaming. The structure change mechanism consists in the dispersion of growing dendrites and crystallization nuclei under the action of shock waves and cumulative jets that occur when cavitation bubbles collapse. The formed fragments of dendrites are new crystallization nuclei that propagate through the melt pool under the action of acoustic currents. Then the process is repeated. The resulting effects affect the kinetics of the crystallization process – the degree of supercooling increases, the number of crystallization nuclei formed per unit time increases, and the rate of its growth decreases. Changes in the structure of the weld metal lead to an increase in the quality of the welded joint, which reduces welding deformations, increases the tensile strength and significantly increases ductility.

Effect of Niobium Supersaturation in Austenite on the Static Recrystallization Behavior of Carbon Structural Steels

This work describes the effect of Nb supersaturation in austenite on the suppression of static recrystallization of austenite during an isothermal holding period following hot deformation. The investigation involved three carbon structural steels with varying Nb concentration at constant C (0.20 pct) and N (0.007 pct) levels. The isothermal double-hit deformation technique led to the determination of T5 pct and T95 pct (recrystallization-stop and full recrystallization temperatures, respectively) as a function of a true strain and interpass time. The results indicate that the T5 pct increases with increasing Nb supersaturation in austenite at a rate of 40 °C per 0.006 pct Nb supersaturation for a true stain ε=0.40. At each respective T5 pct, all tested steels exhibited an Nb supersaturation ratio ≥ 7.5 in austenite. A high, localized strain-induced precipitation of Nb(CN) was observed at the austenite subgrain boundaries in the unrecrystallized microstructure. This translated into higher values for local precipitate-pinning forces (FPIN), which were significantly higher than that predicted from equilibrium thermodynamics. The critical FPIN for retardation of static recrystallization was found to be 1.6 MPa at the respective T5 pct for each steel. The present study has contributed to advancing our knowledge of the interplay between Nb solute supersaturation and volume fraction of Nb(CN) precipitation in particular for carbon structural steels. It has also highlighted an opportunity to apply niobium, even an ultra-low addition (i.e., < 100 ppm) to commodity-grade structural steels to reduce overall alloying costs.

Fluidization‐based chemical vapour deposition for alumina coating on tubular carbon steel substrates—Modelling and validation

AbstractThe degradation of carbon steels due to corrosion and gaseous permeation phenomena can be significantly reduced by a thin alumina coating. Tubular carbon steel structures, commonly employed in nuclear establishments are particularly vulnerable to chemical degradation on the inner surface due to the flow of corrosive fluids. In the present work, a fluidization‐based chemical vapour deposition process is applied as a one‐step solution for simultaneous chemical passivation of both inner and outer substrate surfaces meanwhile optimizing precursor inventory by utilizing fluidized bed sublimation and induction heating techniques. The process is studied by using a 2D‐1D mathematical model, which has been validated with experimental results for different carbon steel grades. It was observed that there exists an optimum fluidization velocity for a specified initial mass fraction of precursor powder at which mass of alumina deposited per unit mass of precursor sublimated is maximized.

Post-fire performance of bonding interface in explosion-welded stainless-clad bimetallic steel

Corrosion in structural steel has significantly adverse effects on the durability of steel structures. The use of stainless-clad bimetallic steel (SCBS) produced via the explosive welding compound method was suggested to mitigate these adverse effects of corrosion. The shear resistant properties of the bonding interface had noteworthy effects on the mechanical performance of SCBS. The steel structure in service was often affected by fire, which had lasting effects on the mechanical performance of the structural steel. An experiment was conducted to clarify the effects of the exposure temperature and cooling method on the shear resistant properties of the bonding interface of the SCBS. An apparent heat affected zone (HAZ) was observed in the explosive welding area. The metallographic structure in carbon steel comprised ferrite and pearlite. The HAZ in carbon steel was mainly composed of ferrite. The changes in the microstructure of SCBS for various exposure temperatures and cooling methods were discussed. After performing mechanical tests, load–displacement curves of the SCBS specimens were obtained. Some resistance parameters were selected to clarify the effects of the exposure temperature and cooling method on the shear resistant properties of the bonding interface of the SCBS. Based on the obtained experimental results, predictive equations were suggested to reveal the variation trend of the resistance parameters. After performing a comprehensive comparison of the experimental and predictive results, it was determined that the suggested multilinear model could be used to predict the shear resistant properties of the bonding interface of SCBS effectively.

ANALYSIS OF SPECIFIC FEATURES OF THE FORMATION OF STRUCTURAL INHOMOGENEITY OF CARBON STEEL (REVIEW)

Purpose. To consider possible factors of influence on the formation of structural and grain unevenness of carbon steel. Methodology. Based on the analysis of the existing literature, the influence of various factors on the structural heterogeneity in carbon steels is analyzed. Results. From the analysis of the literature, a number of reasons were identified that affect the formation of heterogeneity in the structure of carbon steels. These factors include: chemical composition, dendritic liquation and processing liquation, non-metallic inclusions, mechanisms of austenite grain formation, initial grain size, and steel contamination with gases. Scientific novelty. On the part of the chemical composition, chemical elements such as carbon, copper, aluminum, silicon, nitrogen, sulfur and phosphorus affect the liquation formation. The formation of the microliquation level is also significantly influenced by the type of the formed structure. It has been shown that the level of segregation with directional crystallization is much higher than with equilibrium crystallization. Also, the formation of the final structure is associated with a hereditary influence in the production of metal products of the structural features of the parent metal, which depend on various technological factors. The contribution of certain metallogenetic signs of technological heredity occurs at all stages of melting, crystallization, structure formation, solid-phase transformations; different types of thermal, deformation-thermal, deformation processing, etc. In most cases, it is technological factors that are responsible for the structural features and manifestations of the metallurgical and structural heredity of metals and alloys. The dispersion of the dendritic structure, which grows with an increase in the crystallization rate, has a significant effect on the development of dendritic segregation in the ingot. With an increase in the dispersion of the dendritic structure, the total crystallization surface grows and a significant part of the liquid metal solidifies at higher temperatures. Practical significance. As a result of the performed review of the literature, the main factors influencing the formation of the final structural and grain unevenness were determined in accordance with modern points of view. Determination of the basic principles and the most effective factors will make it possible to confidently assume the possible microstructure of steel both in the cast state and after heat treatment.

Influence of warm rolling temperature on multi-scale lamellar structure and mechanical properties of medium carbon steel

Improving the synergy between strength and ductility of medium carbon steel, a multi-scale lamellar structure was developed via hot water quenching and warm rolling at different temperatures. The multi-scale lamellar structure is composed of banded proeutectoid ferrite phase, fine equiaxed ferrite and cementite. The average sizes of subgrains and grains of warm rolled samples at 550 °C is 0.53 μm and 2.3 μm, respectively. When the rolling temperature went up, the fraction of HAGBs increased while the fraction of LAGBs decreased. It is found that the dislocations gradually localized from uniformity with increasing rolling temperature. When the rolling temperature was 650 °C, an obvious substructure was formed, and a large proportion of cementite was spheroidized. The best combination of strength and uniform elongation was obtained by rolling at 550 °C with tensile strength of about 1.2 GPa. In-situ high-energy X-ray study showed that the loads of ferrites with different orientations were similar in the elastic stage, and the stress distribution after yield was significantly different. It is considered that LAGBs strengthening accounts for more than 35%. The strengthening mechanism was verified by in-situ high energy X-ray, and the accuracy of multiscale-LAGBs strengthening theory was verified.

Microstructure and Mechanical Properties of Wire Arc Additively Manufactured Bimetallic Structure of Austenitic Stainless Steel and Low Carbon Steel

Microstructure and Mechanical Properties of Wire Arc Additively Manufactured Bimetallic Structure of Austenitic Stainless Steel and Low Carbon Steel

Effect of Cr on Corrosion Behavior of Laser Cladding Ni-Cr-Mo Alloy Coatings in Sulfuric Acid Dew Point Corrosion Environment

Ni-Cr-Mo alloy coatings with different content of Cr element were produced on carbon structural steel by laser cladding. Coatings exhibited similar phase composition containing γ-Ni solid solution and similar microstructure composed of primary grains and eutectics with segregated Mo. Corrosion behavior of coatings in a sulfuric acid dew point corrosion environment were investigated through the combination of immersion test, electrochemical measurements, and surface analysis. Coatings exhibited similar passive behavior and passive film with a bilayer structure consisting of a compact inner layer and a porous outer layer. An increase in Cr resulted in a more protective passive film with thicker and more compacting inner layer. However, the corrosion resistance was firstly degraded as the content of Cr increased from 18 wt.% to 22 wt.%, and then improved as the content of Cr increased from 22 wt.% to 26 wt.%. This phenomenon was attributed to the competition effect between the increase in Cr and relative decrease in Ni.

Experimental study on mechanical properties and microstructure of PERFORM 700 steel butt-welding joints using in high load-bearing structures

In this paper, an experimental study on butt-welding technology of high strength PERFORM 700 steel plates was reported. The weldability of the base material, the adaptability of the materials to welding, and the mechanical properties of welding joints were assessed by the Radiographic testing (RT) technique, metallographic analysis, tensile test, bend test. The results show that PERFORM 700 steel has good weldability when using Kiswel K-110TK3 MAG flux-cored wire. The weld joint has fine ductility and after the bend test, there is no appearance of cracks or other defects. The welding joint reaches a high strength with yield and ultimate tensile strength of (712.0-720.0) MPa and (830.0-844.1) MPa, respectively. These results are the basis for manufacturing the high load-bearing structures and moreover, it allows a significant reduction of structural mass in comparison with conventional carbon steel structures.

Effect of structure, phase, and elemental composition of AlN, CrAlN, and ZrAlN coatings on their electrochemical behavior in 3% NaCl solution

AbstractThin coatings AlN, AlZrN, and AlCrN were deposited by pulsed magnetron sputtering. The high‐speed steel Т1, structural alloy steel 5140, and structural carbon steel 1017 were used as substrates. The magnetron current, nitrogen content in the gas mixture, and bias voltage on the substrate were changed to obtain nanostructured and amorphous layers of coatings with different elemental compositions. The voltammetry and impedance spectroscopy were performed on the coated samples in 3% NaCl solution. The corrosion behavior of the coatings was characterized by the corrosion current density icorr, the polarization resistance Rp (at the corrosion potential), the ratios icorr,s/icorr, and Rp/Rp,s, where subscript s refers to the substrate. It was shown that the coatings under study (except AlN) are electrochemically active, and the corrosion processes occur not only on the substrate in the coating discontinuity but on the coating surface as well. The coatings AlN/T1, AlZrN/5140, AlCrN/T1, and AlCrN/5140 with icorr ~ 10−7 A cm−2 are found to be the most corrosion‐resistant in 3% NaCl. The paper discusses factors affecting the corrosion behavior of the investigated coatings.

Analysis of temperature field and phase transformation by numerical simulation during welding A516 grade 70 structural carbon steel

The temperature field plays an important role in the fusion welding process, it determines the microstructure and properties of the welded joint. It is very difficult and expensive to determine the temperature in the welded joint experimentally, so this study proposes a solution to determine the temperature field as well as the phase transformation during welding by numerical simulation using SYSWELD software. Through the analysis of the welding temperature field, we can evaluate the ability of the fusion/penetration of joint, the size of the heat-affected zone as well as some welding defects that may be encountered to determine the feasible heat-input range for a specific welding joint. The analysis of welding temperature-time curves will assess the ability to form the hard microstructures such as martensite or bainite that cause brittleness leading to a decrease in the working ability of the welded joint, on that basis, the suitable welding parameter can be found. The research results show that for a butt-welded joint made of A516 grade 70 structural carbon steel with 16 mm thickness, 4 welding runs will have to be welded with the corresponding feasible heat-input ranges respectively of 2252 J/mm ≤ q1 ≤ 2402 J/mm, 2828 J/mm &lt; q2 &lt; 3328 J/mm, 2458 J/mm &lt; q3 &lt; 2518 J/mm and 2878 J/mm &lt; q4 &lt; 3628 J/mm.