Search Results (5)

Internal cracks during slab bending and straightening are continuous-casting defects. Existing caster curves rely on plastic deformation, while curvature variation is concentrated within short sections, causing excessive strain rates and increasing the risk of internal straightening cracks. This study proposes a novel method for slab straightening through creep deformation and develops a curve for an R9300 caster by connecting cubic transition curves with cycloidal main segments. High-temperature tensile and constant-stress creep tests of Q345C steel were combined with transient thermal simulation and geometric strain-rate calculations. Under constraints on caster height, minimum curvature radius, and steady-state creep rate, the optimized parameters were a = 2600 mm and t = 3.6 rad. The curve eliminates the circular-arc section and ensures continuous position, tangent, and curvature. Its bending and straightening sections are each 9379 mm long, increases of 8349 and 7859 mm, respectively, while caster height increases by only 0.47 m. At the internal 1200 °C isotherm, the maximum strain rates are $6.75\times {10}^{-5} {\mathrm{s}}^{-1}$ and $5.19\times {10}^{-5} {\mathrm{s}}^{-1}$, reductions of 82.2% and 81.1% relative to the conventional caster. Both remain below the steady-state creep rate of $7.45\times {10}^{-5} {\mathrm{s}}^{-1}$ under ±10% secondary-cooling and ±10 °C casting-temperature fluctuations. The curve alleviates deformation concentration and enables the slab region at 1200 °C and above to bend and straighten through creep deformation. Full article

The paper presents a critical review of the key work published to date on the hot ductility of steels in relation to the problem of cracking during continuous casting, including recent publications in the field. Laboratory testing methods that are most appropriate for evaluating cracking susceptibility are examined, with particular emphasis on the hot tensile test. The discussion covers both conventional carbon–manganese (C–Mn) and high-strength low-alloy (HSLA) steels, as well as the more complex advanced high-strength steels. Special attention is given to the influence of strain rate and the role of ferrite, both transformation-induced and deformation-induced, in controlling ductility. Increasing the strain rate invariably improves the ductility of steels containing a thin film of ferrite when it is present. This improvement is attributed to the work hardening of the ferrite, which promotes a more uniform distribution of strain, rather than localisation within the thin ferrite layer, thereby reducing the likelihood of fracture. The difficulties in increasing the strain rate in continuous casters are cited. Finally, based on insights from tensile testing, the paper considers practical approaches to preventing cracking in conventional curved-mould and vertical-mould arc continuous casting machines. Newly designed chamfered moulds have also recently been introduced, and these are claimed to reduce the incidence of corner cracking; their role is also discussed. Full article

The design of multi-link vehicle suspension systems, such as the 3D double-wishbone, presents a critical challenge in automotive engineering. The process constitutes a high-dimensional, nonlinearly constrained optimization problem where traditional gradient-based methods often fail by converging to suboptimal local minima. This paper introduces a novel two-stage hybrid optimization framework designed to overcome this limitation by intelligently integrating quantum-inspired and classical techniques. The methodology explicitly defines a QUBO (Quadratic Unconstrained Binary Optimization) stage and an SQP (Sequential Quadratic Programming) stage. Stage 1 addresses the complex kinematic constraint problem by formulating it as a QUBO, which is then solved using Simulated Annealing to perform a global search, guaranteeing a physically feasible starting point. Subsequently, Stage 2 takes this feasible solution and employs an SQP algorithm to perform a high-precision local refinement, tuning the geometry to meet specific performance targets for camber and caster curves. The framework successfully converged to a design with a near-zero performance objective of 7.08 × 10⁻¹⁴. The efficacy of this hybrid approach is highlighted by the dramatic improvement from the high-error initial solution found by Simulated Annealing to the final, high-precision result from the SQP refinement. We conclude that this QUBO-SQP framework is a powerful and validated methodology for solving complex, real-world engineering design problems, effectively bridging the gap between global exploration and local precision. Full article

The existing continuous caster layout curves cause plastic deformation of slabs during bending and straightening segments, while no effective deformation occurs in the basic arc segment, which tends to induce defects, such as cracks, and compromise slab quality. High-temperature creep deformation is generally regarded as detrimental to material performance. If the significant and inevitable creep deformation of a slab could be utilized to accomplish bending and straightening deformation during continuous casting, it would turn a potential harm into an advantage, ultimately enhancing both production efficiency and final product quality. Therefore, a new continuous bending and straightening curve based on the high-temperature creep property of a low-alloy steel slab was designed. The new curve cancelled the original basic arc segment and smoothly connected the bending and straightening segments, which not only substantially prolonged the effective bending and straightening deformation time but also extended the creep time. The locations within the slab corresponding to the temperature range of 1100 °C to 1200 °C were obtained from the simulated temperature field results. Comparing the calculated strain rates with the steady-state creep rates revealed that within the temperature range exhibiting favorable hot ductility, the bending and straightening deformation of the slab could be accomplished entirely through creep deformation. Full article

Aluminum-silicon-magnesium alloys are commonly used in the automotive industry to produce structural components. Among usual quality controls of produced castings, microstructure characterization and determination of mechanical properties are the most critical aspects. However, important problems can be found when measuring mechanical properties in those areas of castings with geometrical limitations. In this investigation, a set of A356 alloys have been prepared and then used to manufacture test castings and automotive castings in a laboratory and in industrial conditions, respectively, using Low Pressure Die Casting (LPDC) technology. Test castings were used to predict secondary dendritic arm spacing (SDAS) by using thermal parameters obtained from experimental cooling curves. The results have been then compared to the ones found in the literature and improved methods for estimating SDAS from cooling curves have been developed. In a subsequent step, these methodologies have been checked with different industrial castings by using simulated cooling curves and experimentally measured SDAS values. Finally, the calculated SDAS values together with the Mg contents present in A356 alloys and the temperature and aging time data have been used to develop new models so as to predict the tensile properties in different areas of a given casting prototype. These developed models allow casters and designers predicting tensile properties in selected areas of a given prototype casting even during design and simulation steps and considering the processing variables expected in a given foundry plant. The structures of these new models have been described and experimentally validated using different processing conditions. Full article