日本神户制钢所（简称KOBELCO）是世界500强之一，是日本第三大钢铁联合企业。该公司创建于1905年，以钢铁制造业、锻造业起家，其前身为1905年9月建立的当时日本国内最大的贸易厂家的神户钢铁厂。1960年公司开启了全球化发展的新纪元，迄今以成为涵盖钢铁、机械、工程、房地产等多个领域；公司在电子和信息系统方面都具有高科技业务。以钢铁业为核心的综合性跨国公司，在日本本土及世界各地控股多家子公司，并设立了多家海外办事机构，公司在日本，美国，亚洲和欧洲都有很多稳定的有一定影响力的公司。 2018年3月6日，社长川崎博也宣布，他将会在4月1日离职，并且再次就事件道歉。负责涉嫌违规的铝铜业务的酊社长金子明亦会辞职。
This study investigates the role of the flux column in the metal transfer process of Flux-Cored Arc Welding (FCAW). Three rutile-type wires with varying flux ratios were compared with metal-cored and solid wires under Ar-CO2 shielding at 220—280 A. Transfer frequencies increased with current for all wires. At 280 A, FCAW and Metal‑Cored Arc Welding (MCAW) showed higher frequencies (142.9 and 240.5 Hz) than Gas Metal Arc Welding (GMAW) (69.8 Hz). At 220 A, FCAW and MCAW showed similar frequencies (82.1 and 71.8 Hz) attributed to long flux or metal columns (un-melted metal core), which prevented neck formation by the Lorentz force. In the 250—280 A range, the MCAW frequency increased significantly, reaching 168
This study investigates the effect of Ca addition on the brittle-to-ductile transition (BDT) and grain boundary decohesion by S segregation in as-quenched low-carbon fully martensitic steel. Temperature dependence of the impact absorbed energy was examined in two kinds of steels with different Ca content (Ca-added steel and Ca-free steel). The BDT temperature of the fully martensitic steel was significantly decreased with the Ca addition. The temperature dependence of the 0.2% proof stress was measured to discuss the decrease in the BDT temperature based on shielding theory. The temperature dependence of 0.2% proof stress was comparable between the two steels, indicating that Ca addition did not affect the dislocation mobility regardless of the Ca content. Observations of brittle fracture surface revealed that intergranular fracture was prominent in the Ca-free steel, whereas it was suppressed in the Ca-added steel. Auger electron spectroscopy further revealed that S was segregated at prior austenite grain boundaries in the Ca-free steel. These results suggest that the improvement in low-temperature toughness in the Ca-added steel is attributed to the increase in surface energy for intergranular fracture, resulting from the suppression of S segregation by Ca addition.
This study investigates the effects of copper (Cu) on pit initiation at manganese sulfide (MnS) inclusions in tempered martensitic steel. The tempered martensitic microstructures and MnS inclusions in Cu-free and Cu-added steels exhibited similar morphologies and compositions. Cu was uniformly distributed within the steel matrix of Cu-added steel, and no Cu enrichment was detected within MnS inclusions or at the inclusion/matrix interface. The Cu-added steel exhibited higher pitting corrosion resistance than the Cu-free steel in a NaCl solution. Polarization conducted using microscale electrode areas revealed that partial dissolution of MnS inclusions occurred within a similar potential range for both steels, indicating that the dissolution behavior was largely unaffected by Cu addition. Although the composition and thickness of surface oxide films on the steel matrix did not substantially differ between Cu-free and Cu-added steels, Cu addition reduced the active dissolution rate of the steel matrix.
The worsening of environmental issues in recent years has prompted the automotive industry to extensively explore the adoption of multi-material structures, particularly those combining steel and aluminum alloys. This strategic shift aims to achieve significant reductions in overall vehicle weight, thereby contributing to enhanced fuel efficiency and decreased emissions. However, when resistance spot welding, a common and widely utilized joining method in the automotive industry, is applied to steel and aluminum alloy, it is known that the peel strength of the joint decreases due to the intermetallic compounds formed at the joint interface. Therefore, in previous studies, the peel strength of the joint was improved by changing the interface shape to a rectangular shape through welding performed after machining. The reason for this is thought to be the change the direction of the intermetallic compound formation on the groove sides. On the other hand, there is a possibility that further improvements in joint strength can be achieved by optimizing the electrode shape on the aluminum side. In this study, the effects of the shape of the aluminum side indentation on the joint strength of the joints with the rectangular interface were investigated. Specifically, a groove was machined into the steel sheets and resistance spot welded to aluminum alloy sheets. When performing the welding, by changing the electrode shape and tip curvature on the aluminum side, the indentation shape was varied. Cross tension tests and tensile shear tests were conducted on the joints made this way. The results showed that changes in the shape of the aluminum side indentation affected the strength of the joint. This is thought to be because the change in the indentation shape on the aluminum side affected the fracture morphology.
This study investigated the fragmentation of glass particles in binary mixtures with alumina, steel, and lead during attrition milling. The fragmentation kinetics, particle size distributions, and fragment morphologies were evaluated experimentally, and kinetic parameters were extracted using a population balance model. Discrete element method simulations clarified the dynamic interactions governing the material-dependent fragmentation. The results indicated that the mechanical properties of the counterpart materials strongly affected the collision intensity and fragment morphology. Alumina induces frequent high-energy collisions and efficient size reduction, producing irregular angular fragments. When lead was used, glass exhibited minimal fragmentation because the collision energy dissipated through plastic deformation during prolonged contact. Steel exhibited moderate fragmentation and generates fragments with low aspect ratios and high circularities suitable for recycling applications. The integration of experiments and simulations elucidated selective comminution mechanisms in heterogeneous systems and demonstrated that fragmentation efficiency and particle morphology can be tuned by the choice of counterpart material. (c) 2025 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).
