Resistance bonding of dissimilar alloys using a powder interlayer: A feasibility study.

An experimental framework has been developed that allows investigation of a novel resistance bonding technique incorporating a metal powder interlayer as a means of forming sound joints between dissimilar alloys. Bonds have been produced between Ti- 6AI-4V, Inconel 718 and super CMV steel. Ti-6-4, BurTi and Inconel 718 powder interlayer layers have been trialed. The use of diffusion barrier coatings and transition layers have been explored with particular interest focussed on the effect of tantalum. These trials were then compared to analysis of corresponding bond chemistries produced by a conventional hot isostatic pressing technique. It was found that joints between Ti-6AI-4V and Inconel 718 and super CMV were prone to the formation of intermetallic films at the interface (NiTi, Ti2Ni, Fe2Ti), resulting in poor bond quality. Whilst the use of diffusion barrier layers reduced reaction zone size, tantalum layers in particular were found to severely degrade joint integrity. Bonds produced between Inconel 718 and super CMV performed more encouragingly; achieving around 70% of Inconel 718 parent metal properties in the optimum condition. Comparisons between conventional HIP procedures and resistance bonding elucidated far better powder consolidation in the former. This was shown to be due to a 'differential heating' effect under resistance heating. A quasi isostatic powder interlayer bonding technique (QUIP) has been developed that has shown to substantially improve joint integrity. This is under continuing development

Combinatorial development and high throughput materials characterisation of steels

A series of small iron specimens with minor additions of C, Si and Mn were manufactured via induction melting and characterised using a high throughput methodology. The aim was to analyse the high throughput approach itself, not the effects of minor additions to steel. Despite their small size, the trends in measured standard mechanical properties were consistent with published data, and target alloy compositions were achieved to a sufficient degree of accuracy. This is most encouraging as the experimental approaches described here delivered results in a very short time frame, with time per composition estimated to be < 2 h per sample. Such an approach would appear to be an excellent precursor to more traditional, expensive and time consuming alloy development methods used by industry. Limitations of the methodology are described, and key bottlenecks are identified. However, the use of small specimens to quantify trends in properties of steels and identify possible new alloys is potentially a valuable addition to the development of new steels

Rapid Alloy Prototyping for a range of strip related advanced steel grades

Over many decades, the traditional route for material product developments, especially in the steel industry has been the laboratory VIM cast route at scale of 25 to 60kg, followed by through-processing of steel ingots involving hot rolling and cooling as well as further downstream processes to simulate finished cold annealed rolled and coated products. This traditional route has so far delivered value for optimising current grades and process routes as well as developing new products prior to production implementation. However, in order to accelerate process and grade developments even smaller scale and faster laboratory synthesis and processing is desired. The AccMet project [1] developed strategies for new alloy development [2,3] and this needs to be further developed to account for the complex processing route for strip steel production. Strategies combining small scale laboratory alloy processing routes, together with mechanical/thermal testing and modelling are being developed, ranging from 20-30g to 4.5 kg [4-8].This paper summarises current Rapid Alloy Prototyping (RAP) approaches and rationale developed under a new UK Engineering and Physical Sciences Research Council (EPSRC) Prosperity project between Tata Steel and the Universities of Swansea and Warwick (WMG). Specific attention is paid to the overall experimental methodology as well as benefits (throughput) of small-scale manufacturing and testing, the generation of representative microstructures for a range of strip grades as well as ways of integrating new concepts which bridge the physical length scale. A range of experimental facilities (20-40g) based on a powder route and induction melting (IM)/heat treatments is being developed to provide material for hot/cold rolling/annealing prior to mechanical testing. Modelling and testing to account for mechanical test specimen size effects for small scale RAP samples is being carried out to ensure consistent mechanical properties are obtained. This small-scale RAP is also being complemented with an intermediate material route operating between 200g and 4.5kg using centrifugal casting and small size ingot vacuum induction melting respectively to provide additional material and throughput sitting alongside the more traditional pilot-scale 25-30kg route. Finally, the 25-30kg standard route is being reviewed to provide a bridge to the laboratory routes through various innovative concepts. This paper concludes with a review of future activities and challenges for effective development and implementation of a range of small scale experimental and pilot manufacturing lines

Evaluating the Suitability of Partial Recrystallization as a Strengthening Method for Thin-Gauge, High-Strength Non-Orientated Electrical Steel

The increasing need for electric/hybrid electric vehicles to compete with fossil fuel-powered cars has led to new requirements and designs of the electric motor. Non-grain oriented steel (NOES) is primarily used within the electric motor to form both stator and rotor sections (dependent on design) and has traditionally been developed to possess excellent isotropic magnetic properties with little or no consideration for strength. The drive toward more powerful or efficient electric motors has resulted in higher rotational speeds and increasing associated requirements for high-strength NOES. This paper looks at utilizing the well-known theory of partial recrystallization as a strengthening mechanism to determine if the strengthening effects and associated magnetic properties are acceptable for use within the rotor section. It was found that partial recrystallization can be utilized to tailor the microstructure of NOES to create higher strength NOES that withstands operating conditions and compares favorably to commercially available high-strength NOES grades, making it a viable option

Indentation Plastometry of Welds

This investigation concerns the application of the profilometry‐based indentation plastometry (PIP) methodology to obtain stress–strain relationships for material in the vicinity of fusion welds. These are produced by The Welding Institute (TWI), using submerged arc welding to join pairs of thick steel plates. The width of the welds varies from about 5 mm at the bottom to about 40–50 mm at the top. For one weld, the properties of parent and weld metal are similar, while for the other, the weld metal is significantly harder than the parent. Both weldments are shown to be approximately isotropic in terms of mechanical response, while there is a small degree of anisotropy in the parent metal (with the through‐thickness direction being slightly softer than the in‐plane directions). The PIP procedure has a high sensitivity for detecting such anisotropy. It is also shown that there is excellent agreement between stress–strain curves obtained using PIP and via conventional uniaxial testing (tensile and compressive). Finally, the PIP methodology is used to explore properties in the transition regime between weld and parent, with a lateral resolution of the order of 1–2 mm. This reveals variations on a scale that would be very difficult to examine using conventional testing

Data modelling and Remaining Useful Life estimation of rolls in a steel making cold rolling process

The economic cost of roll refurbishment in the steel-making industry is considerable. In a cold rolling mill, wear and damage of rolls disrupt the industrial environment, so it is critical to predict the remaining useful life early and change the roll without causing disruption to the manufacturing process. However, since cold rolling is a complex process affected by multiple variables which are operated in adverse conditions, it is very challenging to mathematically analyse the roll wear and failure. For this reason, in the present paper, a data-driven solution is proposed to predict the correct time for changing individual rolls. To develop an accurate predictive model, several datasets containing high-resolution production data and roll refurbishment data collected from a UK based steel plant have been acquired and processed in a way that the roll wear is modelled as a Remaining Useful Life (RUL) problem, where the number of coils that a roll is able to process is viewed as the remaining cycles. Then hybrid deep learning models are used to predict the Remaining Useful Life of rolls used in steel making. This novel data-driven approach achieves high prediction accuracy and has been validated on a real-world dataset. The proposed approach not only helps avoiding early failure but also can serve as a critical step towards the design of an optimal, automated maintenance schedule for the roll management

Mass Manufactured Glass Substrates Incorporating Prefabricated Electron Transport Layers for Perovskite Solar Cells

A commercially available glass substrate which incorporates both a fluorine‐doped tin oxide and compact TiO2 layer deposited through chemical vapor deposition that is commonly used in “solar control products,” is presented. The substrate, known commercially as Pilkington Eclipse Advantage, is designed for use as an infrared radiation control product and this is the first known instance of it being employed and extensively characterized for use as a mass manufactured n‐type contact in perovskite solar cells. Using this substrate with no additional compact TiO2 layer, perovskite solar cells with PCEs of up to 15.9% are achieved. These devices are superior in performance to those where the compact TiO2 is deposited via spray pyrolysis. The reproducibility and large scale manufacturing base already established with this substrate represents significant potential for solving the problem of upscaling a uniform and pinhole free n‐type compact TiO2 blocking layer

Indentation Plastometry of Welds

This investigation concerns the application of the profilometry-based indentation plastometry (PIP) methodology to obtain stress–strain relationships for material in the vicinity of fusion welds. These are produced by The Welding Institute (TWI), using submerged arc welding to join pairs of thick steel plates. The width of the welds varies from about 5 mm at the bottom to about 40–50 mm at the top. For one weld, the properties of parent and weld metal are similar, while for the other, the weld metal is significantly harder than the parent. Both weldments are shown to be approximately isotropic in terms of mechanical response, while there is a small degree of anisotropy in the parent metal (with the through-thickness direction being slightly softer than the in-plane directions). The PIP procedure has a high sensitivity for detecting such anisotropy. It is also shown that there is excellent agreement between stress–strain curves obtained using PIP and via conventional uniaxial testing (tensile and compressive). Finally, the PIP methodology is used to explore properties in the transition regime between weld and parent, with a lateral resolution of the order of 1–2 mm. This reveals variations on a scale that would be very difficult to examine using conventional testing