A review on forming techniques for manufacturing lightweight complex—shaped aluminium panel components

A novel hot stamping process for Ti6Al4V alloy using cold forming tools and a hot blank was presented in this paper. The formability of the material was studied through uniaxial tensile tests at temperatures ranging from 600 to 900°C and strain rates ranging from 0.1 to 5 s−1. An elongation ranging from 30% to 60% could be achieved at temperatures ranging from 750 to 900°C respectively. The main microstructure evolution mechanisms varied with the deformation temperature, including recovery, phase transformation and recrystallization. The hardness of the material after deformation first decreased with the temperature due to recovery, and subsequently increased mainly due to the phase transformation. During the hot stamping tests, qualified parts could be formed successfully at heating temperatures ranging from 750 to 850°C. The forming failed at lower temperatures due to the limited ductility of the material. At temperatures higher than 900 °C, extensive phase transformation of α to β occurred during the heating. During the transfer and forming, the temperature dropped significantly which led to the formation of transformed β, reduction of the formability and subsequent failure. The post-form hardness distribution demonstrated the same tendency as that after uniaxial tensile tests.

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Formability and microstructure evolution mechanisms of Ti6Al4V alloy during a novel hot stamping process

The electropulsing assisted ageing (EAA) processing was proposed as a novel energy-saving heat treatment processing for ageing, and how it influenced the microstructure evolution and mechanical properties of an Al-Mg-Li alloy was investigated in this paper. The mechanical properties and deformation behavior of the alloy were closely correlated with the precipitation and coarsening of the δ′ precipitates. Compared with the conventional ageing (CA), the EAA could accelerate the coarsening of the δ′ precipitates owing to the combination of the electro-migration offering another δ′ precipitate growth coefficient and the enhancement of diffusion due to the interaction between the vacancies and drift electrons, which lowered the ageing temperature for reaching peak-strength under the same ageing time. Besides the strength increased as the coarsening of the δ′ precipitates, the elongation and fracture mode were associated with the volume fraction of the δ′ phase. The easier occurrence of planer slip in the case of the higher volume fraction of the δ′ phase resulted in the low elongation and brittle intergranular fracture of the under-aged and peak-aged alloys, but the slight increase in elongation and reduction of intergranular cracks when the over-ageing occurred. The associated mechanism were discussed in detail.

Study on the microstructure evolution and mechanical properties of an Al-Mg-Li alloy aged by electropulsing assisted ageing processing

Sustainability is a key factor in an automotive OEMs’ business strategy. Vehicle electrification in particular has received increased attention, and major manufacturers have already undertaken significant investments in this area. However, in order to fully confront the sustainability challenge in the automotive industry, lightweight design in additional to alternative propulsion technologies is also required. Vehicle weight is closely correlated with fuel consumption and range for internal combustion and electrified vehicles, respectively, and therefore, weight reduction is a primary objective. Over the past decades, advanced steel and aluminium-forming technologies have seen considerable development, resulting in significant weight reduction of vehicle components. Hot stamping is one of the most established processes for advanced steel and aluminium alloys. The process offers low-forming loads and high formability as well as parts with high strength and minimal springback. However, the high temperatures of the formed materials over numerous cycles and the significant cooling required to ensure desirable component properties necessitate advanced tooling designs. Traditionally, casting and machining are used to manufacture tools; although in recent years, additive manufacturing has gained significant interest due to the design freedom offered. In this paper, a comprehensive review is performed for the state-of-the-art hot-forming tooling designs in addition to identifying the future direction of Additive Manufactured (AM) tools. Specifically, material properties of widely used tooling materials are first reviewed and selection criteria are proposed which can be used for the transition to AM tools. Moreover, key variables affecting the success of hot stamping, for example cooling rate of the component, are reviewed with the various approaches analysed by analytical and numerical techniques. Finally, a number of future directions for adopting additive manufacturing in the production of hot stamping tools are proposed, based on a thorough analysis of the literature.

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Review on additive manufacturing of tooling for hot stamping

Contact solid solution treatment (CST) could make the second phase dissolve into aluminum matrix in a short time. Compared to traditional furnace solid solution treatment（FST）, the fine precipitated phase after CST ageing could make the strength slightly higher than that of T6.

Influence of contact solid-solution treatment on microstructures and mechanical properties of 7075 aluminum alloy

Hot stamping of high-strength aluminium alloy aircraft parts using quick heating

Torsion of the greater omentum is rare and difficult to diagnose preoperatively. There are operative or non-operative treatment options. Operative management is often done for patients with abdominal pain in the right lower quadrant because omental torsion is misdiagnosed as appendicitis. If omental torsion is accurately diagnosed, previous reports suggest that symptoms may improve 12-120 hours after non-operative management of a primary omental torsion. Here, we report a successful case of surgical treatment for torsion of the greater omentum after non-operative treatment was ineffective. Thus, considering the severity of the pain and operative risk, a laparoscopic omentectomy may be feasible to relieve the severe abdominal pain promptly.

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Ryosuke Yachi

Papers

Hot stamping of high-strength aluminium alloy aircraft parts using quick heating

Torsion of the Greater Omentum: A Mimicker of Acute Appendicitis