UltraLight Steel Research Articles

Friction and wear behavior of new light steel reinforced by beryllium alloying

To further reduce the density of light steel and improve its wear resistance, a light-weight wear-resistant steel containing beryllium was developed. In this study, the effects of different loads and Be content on the wear mechanism and microstructure of beryllium steel under slow cooling were evaluated. The results show that the load increases, friction loss and deformation on the surface of each sample increases. Oxidative wear and fatigue wear dominate. As the Be content increases, oxidative wear dominates and wear amount decreases. Beryllium compounds exist and are widely distributed on the surface of the matrix, resulting in an increase in hardness. The new strengthening method of Be−Fe phase provides a possibility for the wear resistance application of ultra-light steel.

A novel dual-heterogeneous-structure ultralight steel with high strength and large ductility

A dual-heterogeneous structure with bimodal grain size distributions of both austenite and B2 phase was developed in a novel ultralight steel by a simple rolling and annealing process. Tensile test results show that the steel annealed at 900 °C (denoted as A900) exhibited the superb synergy of a high specific yield strength of 160.3 MPa g cm−3, a high tensile strength of 1300 MPa, a large ductility of 39.3% and a persistently high work hardening rate, which can be mainly attributed to the heterogeneous structures caused multi-level deformation mechanisms. Detailed microstructural analysis of the deformed A900 samples unveils that with an increase of strain, the plastic deformation of individual austenite grains was governed by different factors, i.e., grain size and Schmid factor (SF) at 4.2% and 9% strains and local stress at 25% strain, while the deformation of individual B2 grains was mainly regulated by grain size at 4.2%, grain size and SF at 9% strain and local stress in the late deformation stage, which leads to the consistently high work hardening rate and large elongation. In addition, owing to the hardness difference, a high density of geometrically necessary dislocations was observed near the interfaces of austenite/B2, which also contribute to the consistently high heterogeneous deformation-induced strengthening effect and thus the outstanding mechanical properties. The present work sheds light on the dual-heterogeneous structure of the ultralight steel that can be feasibly employed, and it could guide the optimization of mechanical performance of a wide range of alloys for lightweight engineering.

Hierarchical Porous Monoliths of Steel with Self-Reinforcing Adaptive Properties.

Porous structures offer an attractive approach to reduce the amount of natural resources used while maintaining relatively high mechanical efficiency. However, for some applications the drop in mechanical properties resulting from the introduction of porosity is too high, which has limited the broader utilization of porous materials in industry. Here, it is shown that steel monoliths can be designed to display high mechanical efficiency and reversible self-reinforcing properties when made with porous architectures with up to three hierarchical levels. Ultralight steel structures that can float on water and autonomously adapt their stiffness are manufactured by the thermal reduction and sintering of 3D printed foam templates. Using distinct mechanical testing techniques, image analysis, and finite element simulations, the mechanisms leading to the high mechanical efficiency and self-stiffening ability of the hierarchical porous monoliths are studied. The design and fabrication of mechanically stable porous monoliths using iron as a widely available natural resource is expected to contribute to the future development of functional materials with a more sustainable footprint.

Hot-stamped B-pillar for automotive driven by Lean 4.0

Lean is applied in automobile companies to reduce lead time and waste through value stream mapping. Industry 4.0 is a process of industrial systems revolution in companies driven by digitalization and data-oriented techniques. The combination of both is called Lean 4.0. In this sense, the purpose of this paper is to attend Ultra-Light Steel Auto-body (ULSAB) automotive requirements through Lean 4.0 framework applied in the fabrication of B-pillar by hot stamping. Optimization algorithms are important to simulate different scenarios and interact with these processes. The proposal was developed in the case study by assessments based on semi-structured questionnaires, analysis of records and documents. The findings showed overall equipment effectiveness (OEE) was increased by 41.5%. The contribution of this work was to meet ULSAB automotive requirements for hot stamping process by reducing vehicle weight while increasing structural strength.

A Study on the Sheet Forming of the Lower Seat Rail using 1180 TRIP Steel

The automotive industry is investing great effort to reduce the weight of vehicles to improve fuel efficiency and performance. To develop a lighter vehicle, Ultra high strength steel (UHSS) is being increasingly used, and is the focus of efforts to develop innovative sheet steel with high strength, durability and formability, including projects such as Ultra-light steel auto body (ULSAB) and Ultra-Light steel auto closure (ULSAC). Because UHSS is very difficult to form at room temperature, roll forming and hot forming processes have been proposed. However, the productivity of these processes is significantly lower than cold forming. In this study, a seven step cold forming process is proposed for forming a lower seat rail using 1180 TRIP steel, and was found to be more conducive to productivity than other processes. The design of the proposed forming process was determined by forming analysis and experiment. The forming analysis was carried out using DEFORM software, and the experiments were carried out using a mechanical press machine. The weight of conventionally formed seat rails (DP 980) and the proposed seat rails (1180 TRIP steel) were compared to determine the weight reduction.

Optimization of Sandwich Monocoque Car Body with Equivalent Shell Element

AbstractThis research proposes a straightforward and efficient method to optimize a sandwich monocoque car body with the developed equivalent shell element based on stiffness equivalence. The fact that stiffness rather than strength is dominant constraint for ordinary car body optimization is demonstrated. A simple but heavy flat chassis plate is utilized as upper bound, while an ideal monocoque is used as lower bound for an actual car body optimization. Convergence hours can be significantly reduced with the equivalent element and the initial-bounded method. A novel electric car body optimization is presented, fulfilling UltraLight Steel Auto Body (ULSAB) stiffness requirements and showing similar optimal weight results as a conventional approach with a much lower analysis time cost.

Automotive door design using structural optimization and design of experiments

Currently, the ultralight steel auto body (ULSAB) concept is receiving more attention owing to various benefits in automotive body design. One of the tasks of the ULSAB is constructing a door using tailor welded blanks (TWBs). In TWBs, two or more gauges of steel panels (parts) are welded together before the stamping process. In this research, the domains and thicknesses of the gauges in a front door structure are determined by a series of optimization methods such as topology, size and shape optimizations and design of experiments (DOE). The door is designed to have better performance compared with an existing structure in terms of stiffness and natural frequency. The final design is discussed and compared with the current design.

Automotive door design with the ULSAB concept. using structural optimization

Weight reduction for an automobile body is sought to achieve fuel efficiency and energy conservation. Recently, the UltraLight Steel Auto Body (ULSAB) concept is suggested using a few methods. ULSAB pursues a lightweight automotive with steel structure. Tailor welded blank (TWB) is one of the ULSAB methods and TWB can be utilized for an automobile door. Optimization technology is applied to the inner panel of a door which is made by TWB. A design process is appropriately defined for the inner panel. The design starts from an existing component. At first, the inner reinforcements are removed to use TWB technology. In the conceptual design stage, topology optimization is conducted to find the distribution of the variable thickness. The number of parts and the welding lines are determined from the topology design. In the detailed design process, size optimization is carried out to find thickness while the stiffness constraints are satisfied. Size optimization is performed based on the welding lines determined from topology optimization. The final parting lines are tuned by shape optimization. The results from size optimization are considered constant in shape optimization. A commercial optimization software GENESIS is utilized for the optimization processes.

ＵＬＳＡＢ‐ＡＶＣ ＵＬＳＡＢ‐ＡＶＣに適用した高張力鋼板と加工プロセス

ＵＬＳＡＢ‐ＡＶＣ ＵＬＳＡＢ‐ＡＶＣに適用した高張力鋼板と加工プロセス

The use of tailored blanks in the manufacture of construction components

A tailor-welded blank consists of steels of different gauges, strengths and coating types welded together to produce a single blank prior to forming. From its basic inception in the mid 1980s to its present status, the tailor-welded blank process has become an important element of automotive component manufacture, progressing from a simple two-piece floor pan application in the Audi 80 to intricate multi-section side panels in modern motor car assemblies. This evolution was assisted to a great extent through research and development undertaken in the collaborative steel and automotive industry project ULSAB (ultra light steel auto body) to produce weight reduction and increased performance in automotive components. This and other developments have resulted in the technology being adopted by a wide range of car manufacturers worldwide. Despite this progress during the 1990s being concentrated in the automotive sector, the advantages offered could be transferred to a number of manufacturing sectors which use sheet steel in production. The building sector is one such group that could benefit from the advanced blanking process. Focused corrosion resistance, increased resistance to concentrated loading and reduced component weight are a few examples of the potential benefits to be gained from the multi-material blanking process. However, a number of manufacturing difficulties need to be overcome to allow the process to be transferred to building applications. The increase in component size from automotive to construction products presents a number of manufacturing obstacles with extended weld length, accurate section cutting and stable clamping requiring review. The surface finish, issues of cost control and blanking distribution will also need to be addressed. Current research into this manufacturing technology for building applications is centred on the use of tailor-welded blanks in a structural panel with strengthened edge details for use in pre-fabricated buildings. This paper address the manufacturing issues outlined above and helps gauge the feasibility of transferring the manufacturing advances achieved by the automotive industry in the 1990s into the present-day construction market.

The life-cycle impacts of aluminum body-in-white automotive material

In this study, life-cycle comparisons of energy usage and CO2 emission of aluminum vs. conventional steel and the ultralight steel auto body were made for body-in-white applications at both the vehicle and fleet levels. The analysis considered three major stages of the life cycle: manufacturing, use, and recycling. The analysis also studied how life-cycle energy and emission benefits are affected by changes in input parameter values, such as manufacturing energy, vehicle-sales growth rate, secondary weight savings, fuel efficiency, and a lower aluminum replacement rate.

The Ultralight Steel Auto Body program completes phase I

The UltraLight Steel Auto Body program was initiated by the American Iron and Steel Institute and the International Iron and Steel Institute. The purpose of the program is to demonstrate the advantages of steel for reducing the weight of the automotive body-in-white. The holistic design approach—considering the body structure, materials, manufacturing methods, and engineering analysis together—has yielded a design for a body-in-white that is about 25 percent lighter than a typical vehicle produced at present, with improved structural performance. The materials and manufacturing processes required for the design are either in use or “near-reach” technologies.