Koldiffusionens inverkan på utmattnings-hållfastheten hos varmvalsade sexkantsstänger;The influence of carbon diffusion on the fatigue strength of hot rolled hexagonal rods

Helstångsborr och konstång kallas bergborrverktyg, som tillverkas av sexkantiga stänger med inre hål för ledning av spolvatten. Dessa spolhål är klädda med ferritiskt rostfritt stål. Innan valsning borras ett centrerat hål i stålämnet som ska valsas. I det borrade hålet appliceras ett rör av ferritiskt rostfritt stål och i det röret skjuts en manganstålskärna in. Efter valsning dras kärnan ut och ett spolhål med invändigt foder av rostfritt stål bildas. Under uppvärmningen och valsningen av stålämnet sker normalt en koldiffusion från manganstålskärnan till det rostfria fodret. Fodrets syfte är att skydda spolhålets yta mot erosion och korrosion.Syftet med arbetet var att hitta en metod som garanterar uppkolning av det invändiga fodret, samt att utreda vad uppkolningen betyder för den mekaniska hållfastheten i stängerna. Ett laboratorieförsök visade att det var bra, med avseende på uppkolning, att blanda stearat i kärnbestrykningsmedlet. Kärnbestrykningsmedlet penslas på manganstålskärnan innan den förs in i stålämnet som ska valsas, dess syfte är att minska friktionen vid kärnutdragningen efter valsning.Ett försök utfördes i valsverket med stearat i kärnbestrykningsmedlet. En grundlig undersökning utfördes på två hetor som valsats med stearat-bestrykningsmedel, samt på en traditionellt tillverkad heta för att ha som referens. Hetorna kapades till provstänger om 1,5 m, totalt undersöktes 55 st.Utvärderingen av verksförsöket visade att stängernas kvalitet blir tillräckligt bra om ingenting oförutsett händer i produktionen, oavsett om koltillskott är tillsatt i bestrykningsmedlet eller inte. Arbetet gav inte en garanterande metod, men visade att stängerna normalt håller hög kvalitet.

Modeling precipitation and its effect on recrystallization during hot strip rolling of niobium steels

Using a physically based model, the microstructural evolution of Nb microalloyed steels during rolling in SSAB Tunnplåt’s hot strip mill was modeled. The model describes the evolution of dislocation density, the creation and diffusion of vacancies, dynamic and static recovery through climb and glide, subgrain formation and growth, dynamic and static recrystallization and grain growth. Also, the model describes the dissolution and precipitation of particles. The impeding effect on grain growth and recrystallization due to solute drag and particles is accounted for. During hot strip rolling of Nb steels, Nb in solid solution retards recrystallization due to solute drag and at lower temperatures strain-induced precipitation of Nb(C,N) may occur which effectively retard recrystallization. The flow stress behavior during hot rolling was calculated where the mean flow stress values were calculated using both the model and measured mill data. The model showed that solute drag has an essential effect on recrystallization during hot rolling of Nb steels.

Humming as a mean of communicating during meal time situations : A Single Case study involving a women with severe dementia and her caregiver

Objective: ‘Music Therapeutic Caregiving’, when caregivers sing for or together with persons with dementia during morning care situations, has been shown to increase verbal and nonverbal communication between persons with dementia and their caregivers, as well as enhance positive and decrease negative emotions in persons with dementia. No studies about singing during mealtimes have been conducted, and this pilot project was designed to elucidate this. However, since previous studies have shown that there is a risk that persons with dementia will start to sing along with the caregiver, the caregiver in this study hummed such that the person with dementia did not sing instead of eat. The aim of this pilot project was threefold: to describe expressed emotions in a woman with severe dementia, and describe communication between her and her caregivers without and with the caregiver humming. The aim was also to measure food and liquid intake without and with humming. Method: The study was constructed as a Single Case ABA design in which the ordinary mealtime constituted a baseline which comprised a woman with severe dementia being fed by her caregivers in the usual way. The intervention included the same woman being fed by the same caregiver who hummed while feeding her. Data comprised video observations that were collected once per week over 5 consecutive weeks. The Verbal and Nonverbal Interaction Scale and Observed Emotion Rating Scale were used to analyze the recorded interactions. Results: A slightly positive influence of communication was shown for the woman with dementia, as well as for the caregiver. Further, the women with dementia showed a slight increase in expressions of positive emotions, and she ate more during the intervention. Conclusion: Based on this pilot study no general conclusions can be drawn. It can be concluded, however, that humming while feeding persons with dementia might slightly enhance communication, and positive expressed emotions in persons with dementia. To confirm this, more studies on group levels are needed. Because previous studies have found that caregiver singing during caring situations influences persons with dementia positively it might be desirable to test the same during mealtime.