The microstructural development of type 321 Austenitic Stainless Steel with long term ageing

Austenitic stainless steel is important in the power generation industry where it is expected to be in service at high temperatures for extended periods of time. Work carried out on the microstructural development of two 321 stainless steel samples has shown that there are complex phase changes that can take place in this alloy. Although the alloy is expected to be fully austenitic at room temperature there is a fraction of ferrite present in the as-received materials. High temperature XRD has shown that this ferrite phase can be dissolved at temperatures between 800 and 900°C but precipitates on cooling at temperatures below 200°C. Due to the low temperature of formation, similarities in chemistry and orientations relationships indicate that the ferrite is forming in a displacive manor from the austenite grains. Thermal ageing at 750°C has been carried out up to times of 15,000 hours and the microstructural changes quantified. The fraction of sigma phase and ferrite increases with ageing time with a corresponding decrease in austenite fraction. This change in the microstructure is postulated to be caused by the changes in the matrix chemistry due to the formation of second phases particles

Evolution of sigma phase in 321 grade austenitic stainless steel parent and weld metal with duplex microstructure

Samples of 321 stainless steel from both the parent and welded section of a thin section tube were subjected to accelerated ageing to simulate long term service conditions in an advanced gas cooled reactor (AGR) power plant. The initial condition of the parent metal showed a duplex microstructure with approximately 50% ferrite and 50% austenite. The weld metal showed three distinct matrix phases, austenite, delta ferrite and ferrite. This result was surprising as the initial condition of the parent metal was expected to be fully austenitic and austenite+delta ferrite in the weldment. The intermetallic sigma phase formed during the accelerated ageing was imaged using ion beam induced secondary electrons then measured using computer software which gave the particle size as a function of aging time. The measurements were used to plot particle size, area coverage against aging time and minimum particle spacing for the parent metal. During aging the amount of ferrite in the parent metal actually increased from ∼50 to ∼80% after aging for 15 000 h at 750°C. Sigma has been observed to form on the austenite/ferrite boundaries as they may provide new nucleation sites for sigma phase precipitation. This has resulted in small sigma phase particles forming on the austenite/ferrite boundaries in the parent metal as the ferrite transforms from the austenite

On the Regioselectivity of the Nickel-Catalyzed Insertion of Alkynes into the Carbon-Carbon Bond of Oxetan-3-one

The study of the regioselectivity of insertion of unsymmetrical alkynes into the carbon–carbon bond of oxetan-3-one in the presence of a nickel catalyst has revealed a strong directing effect of a 2-thienyl substituent. This effect is larger than those of 2-vinylbenzene, trimethylsilyl, aryl, or 3-thienyl groups.</jats:p

Analysis of ferrite formed in 321 grade austenitic stainless steel

A significant fraction of ferrite has been identified in a 321 grade austenitic stainless steel in the solution heat treated condition. The microstructures were analysed using electron backscatter diffraction, energy dispersive X-ray spectroscopy and X-ray diffraction (XRD) and the stability of the ferrite investigated using heat treatments in a tube furnace, dilatometry and high temperature XRD. The ferrite dissolved ,800uC, then formed again on cooling at temperatures under 200uC. Thermodynamic predictions showed a significant ferrite content at room temperature under equilibrium conditions, and the DeLong diagrams predict an austenitezmartensite microstructure in the cast condition. Sensitivity analysis on the DeLong diagram has shown that the nitrogen content had a large effect on the austenite stability. The instability of the austenite and the subsequent transformation to ferrite on cooling can be attributed to low nitrogen content measured in the as received material. It was found that thermal aging of the material caused further transformation of austenite to ferrite as well as the formation of sigma phase that appears higher in nitrogen than the matrix phases. The diffusion of nitrogen into sigma phase may cause instability of the austenite, which could cause further transformation of austenite to ferrite on cooling from the aging temperature. The transformation of austenite to ferrite is known to be accompanied by an increase in volume, which may be of relevance to components made with tight dimensional tolerances

Role extension in advanced ultrasound practice: a framework approach and case study

Introduction: Role extension into novel areas of ultrasound practice can be challenging for health care professionals. Expansion into existing areas of advanced practice typically occurs using established processes and accredited training; however, in areas where there is no formal training, there can be a lack of support for how to develop new and progressive clinical roles. Topic Description: This article presents how the use of a framework approach for establishing areas of advanced practice can support individuals and departments with safely and successfully developing new roles in ultrasound. The authors illustrate this via the example of a gastrointestinal ultrasound role, developed in an NHS department. Discussion: The framework approach comprises three elements, each interdependent upon and inform each other: (A) Scope of practice, (B) Education and competency and (C) Governance. (A) Defines (and communicates) the role extension and area(s) of subsequent ultrasound imaging, interpretation and reporting. By identifying the why, how and what is required this informs (B) the education and assessment of competency for those taking on new roles or areas of expertise. (C) Is informed by (A) and is an ongoing process of quality assurance to safeguard high standards in clinical care. In supporting role extension, this approach can facilitate new workforce configurations, skill expansion and enable increasing service demands to be met. Summary: By defining and aligning the components of scope of practice, education/competency and governance, role development in ultrasound can be initiated and sustained. Role extension utilising this approach brings benefits for patients, clinicians and departments

The effect of long term ageing on the autogenous welding of dissimilar austenitic stainless steels

Austenitic stainless steels are used extensively throughout power stations in high temperature applications such as superheater tubes and fuel rod guides. For these applications, welding is often required to join sections of components or pipes/tubes due to their large sizes and lengths. In this paper, samples of a cast niobium stabilised stainless steel welded to a wrought 321 stainless steel were investigated. The sections were joined together using an autogenous Tungsten Inert Gas (TIG) weld. The effects of long term ageing at 750°C for up to 4000 hours have been studied. The ageing treatments were conducted in an inert atmosphere. Compositional changes and precipitates have been investigated using SEM with EDX and EBSD analysis. Niobium dissolved completely into the weld melt however it is observed to precipitate back out during long term ageing. Titanium carbonitrides however remained intact during the welding process, creating agglomerated particles throughout the weld bead. Ageing above 100 hours causes further Nb rich MX precipitates to form, which coarsen with longer ageing times up to 4000 hours

Influence of oral contrast type and volume on patient experience and quality of luminal distension at MR Enterography in Crohn's disease:an observational study of patients recruited to the METRIC trial

OBJECTIVES: To compare the distention quality and patient experience of oral mannitol and polyethylene glycol (PEG) for MRE. METHODS: This study is a retrospective, observational study of a subset of patients enrolled in a multicentre, prospective trial evaluating the diagnostic accuracy of MRE for small bowel Crohn’s. Overall and segmental MRE small bowel distention, from 105 patients (64 F, mean age 37) was scored from 0 = poor to 4 = excellent by two experienced observers (68 [65%] mannitol and 37 [35%] PEG). Additionally, 130 patients (77 F, mean age 34) completed a questionnaire rating tolerability of various symptoms immediately and 2 days after MRE (85 [65%] receiving mannitol 45 [35%] receiving PEG). Distension was compared between agents and between those ingesting ≤ 1 L or > 1 L of mannitol using the test of proportions. Tolerability grades were collapsed into “very tolerable,” “moderately tolerable,” and “not tolerable.” RESULTS: Per patient distension quality was similar between agents (“excellent” or “good” in 54% [37/68] versus 46% [17/37]) with mannitol and PEG respectively. Jejunal distension was significantly better with mannitol compared to PEG (40% [27/68] versus 14% [5/37] rated as excellent or good respectively). There was no significant difference according to the volume of mannitol ingested. Symptom tolerability was comparable between agents, although fullness following MRE was graded as “very tolerable” in 27% (12/45) of patients ingesting PEG, verses 44% (37/84) ingesting mannitol, difference 17% (95% CI 0.6 to 34%). CONCLUSION: Mannitol-based solutions and PEG generally achieve comparable distension quality and side effect profiles, although jejunal distension is better quality with mannitol. Neither distension quality nor side-effect profile is altered by ingestion of more than 1 L of mannitol. KEY POINTS: • Mannitol-based and PEG-based oral preparation agents generally achieve comparable distension quality for MRE with the exception of the jejunum which is better distended with mannitol. • Mannitol-based and PEG-based oral preparation agents used for MRE have similar side effect profiles. • Neither distension quality nor side-effect profile is altered by ingestion of more than 1 L of mannitol. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00330-022-08614-9

INSPIRE (INvestigating Social and PractIcal suppoRts at the End of life): Pilot randomised trial of a community social and practical support intervention for adults with life-limiting illness

YesBACKGROUND: For most people, home is the preferred place of care and death. Despite the development of specialist palliative care and primary care models of community based service delivery, people who are dying, and their families/carers, can experience isolation, feel excluded from social circles and distanced from their communities. Loneliness and social isolation can have a detrimental impact on both health and quality of life. Internationally, models of social and practical support at the end of life are gaining momentum as a result of the Compassionate Communities movement. These models have not yet been subjected to rigorous evaluation. The aims of the study described in this protocol are: (1) to evaluate the feasibility, acceptability and potential effectiveness of The Good Neighbour Partnership (GNP), a new volunteer-led model of social and practical care/support for community dwelling adults in Ireland who are living with advanced life-limiting illness; and (2) to pilot the method for a Phase III Randomised Controlled Trial (RCT). DESIGN: The INSPIRE study will be conducted within the Medical Research Council (MRC) Framework for the Evaluation of Complex Interventions (Phases 0-2) and includes an exploratory two-arm delayed intervention randomised controlled trial. Eighty patients and/or their carers will be randomly allocated to one of two groups: (I) Intervention: GNP in addition to standard care or (II) Control: Standard Care. Recipients of the GNP will be asked for their views on participating in both the study and the intervention. Quantitative and qualitative data will be gathered from both groups over eight weeks through face-to-face interviews which will be conducted before, during and after the intervention. The primary outcome is the effect of the intervention on social and practical need. Secondary outcomes are quality of life, loneliness, social support, social capital, unscheduled health service utilisation, caregiver burden, adverse impacts, and satisfaction with intervention. Volunteers engaged in the GNP will also be assessed in terms of their death anxiety, death self efficacy, self-reported knowledge and confidence with eleven skills considered necessary to be effective GNP volunteers. DISCUSSION: The INSPIRE study addresses an important knowledge gap, providing evidence on the efficacy, utility and acceptability of a unique model of social and practical support for people living at home, with advanced life-limiting illness. The findings will be important in informing the development (and evaluation) of similar service models and policy elsewhere both nationally and internationally. TRIAL REGISTRATION: ISRCTN18400594 18(th) February 2015

Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

A small scale sample nuclear waste package, consisting of a 28 mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500 keV), with a source size of <0.5 mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30 cm2 scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10 Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned