The surface evolution of vermicular cast iron in a high frequent cyclic plasma and facial cooling airflow was studied to understand the behavior and mechanism in different cooling conditions under a unique thermal shock environment. Results indicated that both the mass and linear loss presented titled inverted V-shaped relationships with the flux of the cooling airflow, while the change in roughness decreased continuously. As the cooling airflow rose, the eroded zone was reduced, the iron oxides lessened, and fluctuation of the surface temperature weakened. In combination with the thermodynamic calculations and thermal analysis, it was confirmed that the oxidation and mechanical erosion had contrary tendencies with the rising flux in the facial cooling airflow. The transformation of the dominant factor from oxidation to peeling off by thermal stress and scouring resulted in the evolution of mass and thickness. The surface oxides dominated the change in the roughness. Full article

This study explored the buckling performance of bi-segment pressure hulls under external pressure. We fabricated bi-segment pressure hulls from bi-segment cylindrical preforms by using free bulging. The cylindrical preforms had a nominal thickness of 0.95 mm, nominal radius of 51 mm, and nominal height of 242 mm. Six bi-segment pressure hulls were hydrostatically and externally pressurised into buckling. Experimental results revealed that the maximum buckling load of the bi-segment pressure hulls was increased by 36.75% compared with that of the bi-segment cylinders. In addition, we performed a nonlinear finite element analysis to determine the bulging and buckling modes of the hulls. We noted that the nonlinear analysis results exhibited good agreement with the experimental data. Full article

In the present study, a dry sliding wear test has been conducted to analyse the wear rate of Ti-6Al-4V alloy specimens which were fabricated using selective laser melting and conventional methods. Microstructure, micro- and nanohardness, and wear behaviour of selective laser melting specimens were investigated and compared with commercially available conventionally fabricated Ti-6Al-4V specimens. The mechanism correlating microstructure and wear behaviour of conventional and selective laser melting based Ti-6Al-4V specimens have been explained. The microhardness of the selective laser melting specimen was improved by around 22.4% over the specimen from the conventional method. The selective laser melting specimen showed broadened peaks and an increase in intensity height greater than that of the conventional specimen due to the presence of the martensite phase. The selective laser melting specimen possessed 41.4% higher nanohardness than that of the conventional specimen. The selective laser melting specimen had a 62.1% lower wear rate when compared to that of the conventional specimen. The selective laser melting specimen exhibited 62.7% less coefficient of friction than that of the conventional specimen at a 50 N load with 1.2 m/s sliding velocities. The finer needle-like microstructures of the specimen produced using the selective laser melting process had higher wear resistance, as it had higher hardness than the conventional specimen. Full article

Taking an oxygen-rich side-blown lead melting furnace made by a company as the research object, the three-dimensional design software Solidworks was used to construct a model at an equal scale, and established a physical model which is in line with the actual system. Based on the determination of the physical properties of the slag phase and metal phase in the furnace, the VOF multiphase flow model and standard turbulence model in FLUENT were used to simulate the gas–liquid multiphase flow. By adjusting the different inclination angles of the spray gun, we analyzed the distribution changes of key indicators, such as the flow field, average turbulent kinetic energy and gas content in the furnace. At the same time, it was found that the turbulent kinetic energy in the middle of the furnace was large, which could strengthen the winding effect of the material and the best arrangement. The gas content of the upper part of the oxygen gun was high, and the gas content in the middle of the furnace was higher than that in the wall area on both sides and showed a gradual downward trend. If the inclination angle of the spray gun is too small, the agitation of the lower melting area is not strong enough, On the contrary, if the inclination angle is too large, the local flow rate of the sedimentation area increases and the gas content is low. The optimal tilt angle of the spray gun is between 10° and 15°. Full article

Slag compositions are significant for the viscosity of blast furnace slag. An improved Urbain model (IUM) was proposed by introducing R₅ ((X(CaO) + X(MgO) + 2X(TiO₂))/(2X(SiO₂) + 3X(Al₂O₃))) and N (X(MgO)/3X(Al₂O₃)) as the model parameters. By comparing IUM with other models, the model parameters of R₅ and N are more reasonable and suitable for TiO₂-bearing blast furnace slag, and IUM for predicting viscosity has a higher precision, and its relative error is only 10%. The viscosity isolines of the CaO–SiO₂–15%Al₂O₃–MgO–2.5% TiO₂ system were plotted, and the results show that the viscosity center of the slag is between R_w2 (w(CaO)/w(SiO₂)) = 0.77–1.39 and N_w (w(MgO)/w(Al₂O₃)) = 0–1.37, the value of the viscosity center is 0.3 Pa·s, the viscosity increases gradually from the center to the outside, and the viscosity of the slag gradually decreases with the increase in N_w and R_w2. Furthermore, FTIR (Fourier Transform Infrared Spectroscopy) analysis was carried out in order to understand the mechanism between the slag structure and viscosity. With the increase in N_w and R_w2, the peak values of the symmetrical stretching vibration of non-bridging oxygen in the Si–O tetrahedral structure of slag decrease, and the slag structures depolymerize, which leads to the decrease in the viscosity of the slag. Full article

Casting is a fabrication method used to create various industrial parts with different shapes. Flaws such as shrinkage, porosity, and short metal filling can result in casting rejection. These flaws are heavily reliant on casting parameter design (gating and riser system design) and can be reduced by optimizing the casting parameter design. The development of materials with new or improved properties has long been the primary objective of materials scientists. The designing of metallic alloys for structural purposes must take strength, toughness, and formability into account to achieve the desired performance. The unique convergence of these essential characteristics that characterize high manganese steels fascinate scientists worldwide. The current work systematically investigated a gating system and riser design effect for high Manganese steel samples (bushes) to develop an understanding of the structure–property relationship. The first conventional manual calculation was performed to design the gating and riser system. Subsequently, a sophisticated simulation software called SolidCast was used to design, validate, and improve the casting parameters of the specimen. To back up the findings, confirmatory experiments were carried out. Both designs were used to make castings in order to check for flaws. The microstructural and mechanical characteristics of these materials were investigated. Visual inspection of the manually-designed castings revealed considerable shrinkage, whereas software-designed castings seemed in good shape, without the shrinkage, macroporosity, and microporosity. The microstructure of the specimens was also studied by applying optical microscopy and SEM analysis. By improving the gating and riser system with the SolidCast software, sound casting was achieved. This improved the quality of casting results with a considerable enhancement of yield strength (~32 percent), hardness (~34 percent), and tensile strength (~27 percent), which may lead to significant cost savings. Full article

During the explosive welding, the bonding interface of welded materials was fast heated due to high strain rate and drastic plastic deformation. The periodical wave interface, with an amplitude of ~300 μm and a period wavelength of ~800 μm, was identifiable as a uniform wave interface formed in the bonding interface. The details of the formation of melting zone and mixing zone of welding materials at the interface were observed. Combined with the Ti-Fe binary phase diagram and the principle of diffusion welding, the phase composition and evolution process of the melting and mixing zone of the bonding interface were investigated by transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). Significance of the intermetallic compound was found in the mixing zone and melting zone, which was mainly TiFe, TiFe₂, TiO₂, Fe₂O₃ and some other intermetallic oxides. Meanwhile, the phenomenon of the titanium agglomeration and oxygen precipitation was observed in the melting zone. The bonding interface could be determined as a mixing welding of mechanical mixing, melting, diffusion and solidification that occurred in the mixing zone, and melting welding and diffusion welding mainly occurred in the melting region. Full article

In this study, the heat treatment process of a high-chromium cast iron (HCCI) alloy prepared via 128 MPa squeeze casting at different subcritical quenching temperatures was investigated. The results showed that subcritical heat treatment can change the martensite content, the carbide type and size of the squeeze casting HCCI microstructure. Furthermore, it was revealed that the subcritical quenching heat treatment can improve the hardness of the liquid-forged HCCIs. When the quenching temperature increased from 500 °C to 530 °C, the hardness of the alloy increased significantly, reaching a maximum value of 57 HRC. Thereafter, if the temperature continued to rise to 630 °C, the hardness decreased rapidly. For impact toughness, when the quenching temperature was 500 °C, the toughness of alloy increased by 0.9 J/cm² than that of the no heat treatment group. If the quenching temperature continued to increase, the toughness was reduced. Taking hardness and toughness into account, the microstructure evolution diagram of the optimal process-500 °C subcritical quenching process was established, various characterisation techniques were used to gain insights into the optimal heat treatment process. Compared with high temperature heat treatment, subcritical heat treatment can improve the performance of the HCCI alloy and reduce costs. Full article

Resource utilization of SO₂ from flue gas is a key challenge for the green development of the smelting industry. Recovery of sulfur resources in the form of elemental sulfur (S⁰), which has a high market demand and is a current focus in the field of SO₂ treatment, can reduce the solid waste from desulfurization. In this study, it was found that Pb as a cathode material had good catalytic activity for the electrochemical reduction of SO₂ and good selectivity towards elemental sulfur. However, the cathode suffers from sulfur poisoning. The problem was resolved by introducing surfactant, specifically sodium dodecyl benzene sulfonate (SDBS), which significantly lowered the sulfur content ratio on the surface of the electrode from 31.82% to 2.17%. Through the optimization of electrocatalytic parameters, this method enables efficient conversion of SO₂ to S⁰, achieving a selectivity of 83% at pH = 0.25 and E = −0.8 V (vs. SCE). Full article

Incremental sheet forming (ISF) requires no or partial dies for sheet metal fabrication and is widely used for small batch production. In this process, necking is either suppressed or delayed due to the localized nature of tool–sheet contact; hence, more strains than conventional stamping and deep drawing are obtained. In the present study, two variations of ISF, namely cold ISF (CISF) and warm ISF (WISF), are compared. First, FEA modeling is carried out on ABAQUS to reach the forming forces involved in the process. It is found that WISF reduces the forming forces. The temperature for WISF is maintained at 180 °C. Following the simulation analysis, tests are carried out. The forming force in WISF is 55.77% less than that in CISF. The part fabricated by CISF is slightly more substantial than that by WISF; however, more forming depth can be achieved by WISF. There is a more uniform thickness distribution in the case of CISF than in WISF. However, the surface quality of the CISF product is inferior to that of WISF. It is observed that there is reduced forming force, increased formability, and better strain distribution in WISF compared to CISF. However, post-processing heat treatment and surface polishing of the formed parts is required to restore their mechanical properties. Full article

Herein, the chloride-induced stress corrosion cracking (SCC) mechanisms of UNS S32205 duplex stainless steel (DSS) reinforcing bars in alkaline and carbonated solutions are studied. Electrochemical monitoring and mechanical properties were tested using linear polarization resistance and electrochemical impedance spectroscopy, coupled with the slow strain rate tensile test (SSRT) to evaluate the SCC behavior and unravel the pit-to-crack mechanisms. Pit initiation and crack morphology were identified by fractographic analysis, which revealed the transgranular (TG) SCC mechanism. HCO₃⁻ acidification enhanced the anodic dissolution kinetics, thus promoting a premature pit-to-crack transition, seen by the decrease in the maximum phase angle in the Bode plot at low frequencies (≈ 1 Hz) for the carbonated solution. The crack propagation rate for the carbonated solution increased by over 100% compared to the alkaline solution, coinciding with the lower phase angle from the Bode plots, as well as with the lower charge transfer resistance. Pit initiation was found at the TiN nonmetallic inclusion inside the ferrite phase cleavage facet, which developed TG-SCC. Full article

The effects of annealing time on microstructure, mechanical properties, and corrosion resistance of Ti-0.3Mo-0.8Ni (TA10) titanium alloy hot-rolled sheets are investigated. With the increase in annealing time, the α → β phase transition occurs, and the grain size grows gradually. The strength deteriorates, and elongation increases. The grains grow up, the number of grain boundaries decreases, and intergranular corrosion decreases. With the increase in the annealing time, the corrosion kinetics and thermodynamics are enhanced. When annealed at 780 °C for 2 h, TA10 alloy sheets exhibit the best comprehensive properties, and its microstructure is composed of fine equiaxed α phase. The mechanical properties and corrosion resistance are improved. Full article

Different from the cross-section profile defects caused by uneven roll wear or external forces during hot finishing rolling, the edge warping defect often occurs and has special local characteristics. However, the cause and control method of edge warping are still unclear. By superposition calculating the roll shape, it is found that the high-order comprehensive roll gap contour formed by the superposition of the bathtub-shaped roll thermal contour and parabolic original roll shape is the main cause of strip edge warping. To ensure that the comprehensive roll gap contour is parabolic rather than the original roll shape, the target curve of the comprehensive roll contour in the form of a parabola is determined according to the amplitude of the middle position of the comprehensive roll contour of the last strip in a standard rolling unit, and then subtract the thermal contour curve of the last strip to obtain the desired curve of the antithermal original roll shape. In theory and application, the optimization of the original roll shape can effectively avoid the occurrence of edge warping defect. Full article

The buckling failure of thin-walled circular shells under local axial compression is common in engineering. This study uses the vector form intrinsic finite element (VFIFE) method to investigate the buckling behavior of thin-walled circular shells under local axial compression by introducing a multilinear hardening model, taking into account geometric and material nonlinearity. A buckling analysis program based on the VFIFE method was developed and verified by comparison with experimental results. The buckling mode and postbuckling behavior of thin-walled circular shells were studied by using the verified program. The results show that the VFIFE method with a multilinear hardening model can accurately calculate the buckling load of local axially compressed thin-walled circular shells, and effectively simulate the buckling development process, which offers great advantages in predicting the postbuckling of structures. Full article

In this work, the hydrogen fatigue of pipeline steel X60, its girth welds and weld defects were investigated through in situ fatigue testing. A novel in situ gaseous hydrogen charging fatigue set-up was developed, which involves a sample geometry that mimics a small-scale pipeline with high internal hydrogen gas pressure. The effect of hydrogen was investigated by measuring the crack initiation and growth, using a direct current potential drop (DCPD) set-up, which probes the outer surface of the specimen. The base and weld metal specimens both experienced a reduction in fatigue life in the presence of hydrogen. For the base metal, the reduction in fatigue life manifested solely in the crack growth phase; hydrogen accelerated the crack growth by a factor of 4. The crack growth rate for the weld metal accelerated by a factor of 8. However, in contrast to the base metal, the weld metal also experienced a reduction of 57% in resistance to crack initiation. Macropores (>500 µm in size) on the notch surface reduced the fatigue life by a factor of 11. Varying the pressure from 70 barg to 150 barg of hydrogen caused no difference in the hydrogen fatigue behavior of the weld metal. The fracture path of the base and weld metal transitioned from transgranular and ductile in nature to a mixed-mode transgranular and intergranular quasi-cleavage fracture. Hydrogen accelerated the crack growth by decreasing the roughness- and plasticity-induced crack closure. The worst case scenario for pipelines was found in the case of weld defects. This work therefore highlights the necessity to re-evaluate pipelines for existing defects before they can be reused for hydrogen transport. Full article