Frictional behaviour and wear performance of a nitrocarburised coating sliding against AISI 1019 steel

This work employed a commercial nitrocaburising process to diffuse a coating onto M2 grade high speed tool steel. Properties of the nitrocaburised coating (CN) such as thickness, roughness and hardness were characterised using a variety of techniques including Glow-Discharge Optical Emission Spectrometry (GD-OES) and Scanning Electron Microscopy (SEM). A tribological test has been developed in which two nominally identical crossed cylinders slide over each other under selected test conditions. The test has been employed to investigate the wear performance of both CN coated and uncoated M2 specimens and frictional behaviour of the sliding interface between the tool and a AISI 1019 steel workpiece under unlubricated (dry) and lubricated conditions. Fourier Transform Infrared Spectroscopy (FTIR) was used to monitor the formation of chemical species from the oxidation of lubricant during tribological testing. <br /

Inferring dynamic recrystallization in ferrite using the kinetics of static recrystallization

A general relationship between the kinetics of dynamic and static recrystallization is developed. It is predicted that conventional dynamic recrystallization will occur whenever the deformation time exceeds the adjusted start time for static recrystallization. This approach is verified using data for austenite and lead. It is then applied to current and previous work on ferrite. The model provides support for the contention that conventional dynamic recrystallization occurs in low carbon ferrite if deformation is carried out at high temperatures and low strain rates. In the present work, which was carried out at 700 &deg;C, evidence for dynamic recrystallization was observed for strain rates less than around 0.01 s&minus;1. At higher strain rates, the model predicts a critical strain for the onset of dynamic recrystallization that exceeds the critical strain for the beginning of the recovery steady-state region. While the model allows dynamic recrystallization to begin in this region, the critical strain for its onset is expected to increase rapidly with increasing strain rate and decreasing temperature once steady state has been reached. <br /

A nitrocarburising and low-temperature chromising duplex surface treatment

A duplex surface treatment has been developed involving the pre-treatment of hardened and tempered AISI H13 chromium hot-work tool steel by a ferritic nitrocarburising process, and a subsequent treatment of the nitrocarburised surface by a low-temperature chromium thermo-reactive deposition process.&nbsp; The process formed a thin and hard chromium carbonitride surface layer above a hardened diffusion zone, and the low processing temperature allowed the properties of the core material to be retained. It is expected this surface treatment will find application in the treatment&nbsp; of tooling used for aluminium forming operations. <br /

Using photo-elicitation to explore young people’s short-term experience of orthodontic retainers

Background: Adherence to retainer wear following orthodontic treatment is known to prevent relapse, if worn as advised. However, non-adherence is a persistent and widespread problem for young people. Aim: To investigate young people’s lived experience of retainer wear and the factors affecting adherence in the immediate term following completion of their orthodontic treatment. Design: Qualitative study using photo-elicitation, underpinned by a relativist ontology, constructivist epistemology and an interpretivist methodology. Methods: 12 participants aged 13-18 were recruited from two teaching hospitals, Leeds Dental Institute and Bradford Hospitals NHS Teaching Trust, using a purposive sampling approach. Data collection occurred through one-to-one, virtual, photo-elicitation interviews. Recruitment continued until it was deemed that data saturation had been reached. Analysis: Interpretative phenomenological analysis (IPA). Results: Three overarching themes were developed to describe young people’s experience, including their immediate experience and expectation of retainers, the process of adaptation and motivating factors. Challenges to adherence were mostly ascribed to day-time wear, despite normalisation of retainers in young people’s lives. Interventions to help individuals overcome the initial adaptation phase and self-manage their foreseen problems of forgetfulness include routines, reminders and compensatory changes in behaviours. Internal motivation, external motivation and self-determination significantly contribute to retainer adherence immediately following treatment completion. Conclusions: Factors associated with young people’s immediate experience of orthodontic retention are complex and multifaceted, comprising a web of influential factors that overlap. Thoughtful consideration of young people’s capability, opportunity and motivation toward retainer wear may enable orthodontists to understand the nuances of their behaviour whilst optimising and co-constructing strategies for adherence on an individual basis

Soil governance in the agricultural landscapes of New South Wales, Australia

Soil is a valuable natural resource. In the state of New South Wales, Australia, the governance of soil has evolved since Federation in 1901. Following rapid agricultural development, and in the face of widespread soil degradation, the establishment of the Soil Conservation Service marked a turning point in the management of soil. Throughout the 20th century, advances in knowledge were translated into evolving governance frameworks that were largely reactionary but saw progressive reforms such as water pollution legislation and case studies of catchment-scale land and vegetation management. In the 21st century, significant reforms have embedded sustainable use of agricultural soils within catchment- and landscape-scale legislative and institutional frameworks. What is clear, however, is that a multitude of governance strategies and models are utilised in NSW. No single governance model is applicable to all situations because it is necessary to combine elements of several different mechanisms or instruments to achieve the most desired outcomes. Where an industry, such as the sugar industry, has taken ownership of an issue such as acid sulfate soil management, self-regulation has proven to be extremely effective. In the case of co-managing agricultural soils with other landuses, such as mining, petroleum exploration and urban development, regulation, compliance and enforcement mechanisms have been preferred. Institutional arrangements in the form of independent commissioners have also played a role. At the landscape or total catchment level, it is clear that a mix of mechanisms is required. Fundamental, however, to the successful evolution of soil governance is strategic investment in soil research and development that informs the ongoing productive use of agricultural landscapes while preventing land degradation or adverse environmental effects

Galling reduction through die surface treatment - testing three treatments for sheet metal stamping

This brief article describes how tool galling occurs in stamping and describes results of tests on how TiCN, Hard-Cr, and CrCN were used on sample parts to help reduce galling.<br /

Formation of ultrafine grained microstructures in steel through strain induced transformation during single pass hot rolling

In the present study, wedge-shape samples were used to study the effect of strain induced transformation on the formation of ultrafine grained structures in steel by single pass rolling. The results showed two different transition strains for bainite formation and ultrafine ferrite (UFF) formation in the surface layer of strip at reductions of 40% and 70%, respectively, in a plain carbon steel. The bainitic microstructure formed by strain induced bainitic transformation during single pass rolling was also very fine. The evolution of UFF formation in the surface layer showed that ferrite coarsening is significantly reduced through strain induced transformation combined with rapid cooling in comparison with the centre of the strip. In the surface, the ferrite coarsening mostly occurred for intragranular nucleated grains (IG) rather than grain boundary (GB) ferrite grains. The results suggest that normal grain growth occurred during overall transformation in the GB ferrite grains. In the centre of the strip, there was significantly more coarsening of ferrite grains nucleated on the prior austenite grain boundaries.<br /

Surface analysis of carbon fibre composite laminates for automotive body panels

This paper compares the surface finish of carbon fibre composite laminates manufactured from autoclave and QuickstepTM processes, primarily for automotive body panel applications. The arithmetic mean surface roughness, Ra, of tape and twill carbon fibre composites, manufactured using both Quickstep and autoclave processes, was measured. The effect of surface film on Ra was also investigated. Results indicated that the laminates without surface films, manufactured using Quickstep (tape Ra 0.061 pm, twill Ra 0.043 pm) and autoclave (tape Ra 0.034 pm, twill Ra 0.056 pm) processes had the lowest Ra. Autoclave manufactured tape laminates had lower surface roughness than the equivalent twill laminates using the same lay-up configurations and surface films. In contrast, Quickstep manufactured twill laminates had a lower surface roughness than the tape laminates. The application of one layer of SynSkin or Plastilock surface film increased the surface roughness in all instances and after applying two layers of surface film, the surface roughness was further reduced

Effects of temperature in relation to sheet metal stamping

The demand to reduce the use of lubricants and increase tool life in sheet metal stamping has resulted in increased research on the sliding contact between the tool and the sheet materials. Unlubricated sliding wear tests for soft carbon steel sliding on D2 tool steel were performed using a pin-on-disk tribometer. The results revealed that temperature has an influencing role in the wear of tool steel and that material transfer between tool and sheet can be minimized at a certain temperature range in sheet metal stamping