The following report conducted by the theoretical research and experimental study in the University of Halmstad. The focus of the project is experimental investigation on weld characteristics for shield metal arc welding with SS304 & SS409. Welding is a joining process of similar metals but nowadays it is also joined dissimilar metals by the application of heat. The different types of welding process are available in industry. Welding can be done with or without the application of pressure and filler materials in shielded metal arc welding (SMAW), an arc between a covered electrode and a weld pool is used to accomplish a weld. As the welder steadily feeds the covered electrode into the weld pool, the decomposition of the covering evolves into gases that shield the pool. Austenitic stainless steel and Martensitic chrome alloys is widely used materials in the current industrial area including higher and lower temperature applications such as storage tanks, pressure cups, furnace equipment’s etc. This paper concentrated to the investigate the dissimilar material joining by using shield metal arc welding and study the welding characteristics and do the mechanical tests. The aim of this study performance of steel and maximum hardness of welded material, microstructure of steel on next phase of project. The results will be used to character of dissimilar material performance.

Nanocrystalline materials have generated immense scientific interest, primarily due to observations of significantly enhanced strength and hardness resulting from Hall-Petch grain size strengthening into the nano-regime. Unfortunately, however, most previous studies have been unable to present material strength measurements using established tensile tests because the most commonly accepted tensile test protocols call for specimen geometries that exceeded the capabilities of most nanocrystalline material synthesis processes. This has led to the development of non-standard mechanical test methodologies for the evaluation of miniature specimens, and/or the persistent use of hardness indentation as a proxy for tensile testing. This study explored why such alternative approaches can be misleading and revealed how reliable tensile ductility measurements and material strength information from hardness indentation may be obtained. To do so, an electrodeposition-based synthesis method to produce artifact-reduced specimens large enough for testing in accordance with ASTM E8 was developed. A large number of 161 samples were produced, tested, and the resultant data evaluated using Weibull statistical analysis. It was found that the impact of electroforming process control on both the absolute value and variability of achievable tensile elongation was strong. Tensile necking was found to obey similar processing quality and geometrical dependencies as in conventional engineering metals. However, unlike conventional engineering metals, intrinsic ductility (as measured by maximum uniform plastic strain) was unexpectedly observed to be independent of microstructure over the grain size range 10-80nm. This indicated that the underlying physical processes of grain boundary-mediated damage development are strain-oriented phenomena that can be best defined by a critical plastic strain regardless of the strength of the material as a whole. It was further shown that the HV = 3•σUTS expression is a reliable predictor of the relationship between hardness and strength for electrodeposited nanocrystalline materials, provided the material is ductile enough to sustain tensile deformation until the onset of necking instability. The widely used relationship HV = 3•σY was found to be inapplicable to this class of materials owing to the fact that they do not deform in an “ideally plastic” manner and instead exhibit plastic deformation that is characteristic of strain hardening behaviour.

Nanocrystalline materials have generated immense scientific interest, primarily due to observations of significantly enhanced strength and hardness resulting from Hall-Petch grain size strengthening into the nano-regime. Unfortunately, however, most previous studies have been unable to present material strength measurements using established tensile tests because the most commonly accepted tensile test protocols call for specimen geometries that exceeded the capabilities of most nanocrystalline material synthesis processes. This has led to the development of non-standard mechanical test methodologies for the evaluation of miniature specimens, and/or the persistent use of hardness indentation as a proxy for tensile testing. This study explored why such alternative approaches can be misleading and revealed how reliable tensile ductility measurements and material strength information from hardness indentation may be obtained. To do so, an electrodeposition-based synthesis method to produce artifact-reduced specimens large enough for testing in accordance with ASTM E8 was developed. A large number of 161 samples were produced, tested, and the resultant data evaluated using Weibull statistical analysis. It was found that the impact of electroforming process control on both the absolute value and variability of achievable tensile elongation was strong. Tensile necking was found to obey similar processing quality and geometrical dependencies as in conventional engineering metals. However, unlike conventional engineering metals, intrinsic ductility (as measured by maximum uniform plastic strain) was unexpectedly observed to be independent of microstructure over the grain size range 10-80nm. This indicated that the underlying physical processes of grain boundary-mediated damage development are strain-oriented phenomena that can be best defined by a critical plastic strain regardless of the strength of the material as a whole. It was further shown that the HV = 3•σUTS expression is a reliable predictor of the relationship between hardness and strength for electrodeposited nanocrystalline materials, provided the material is ductile enough to sustain tensile deformation until the onset of necking instability. The widely used relationship HV = 3•σY was found to be inapplicable to this class of materials owing to the fact that they do not deform in an “ideally plastic” manner and instead exhibit plastic deformation that is characteristic of strain hardening behaviour.

This study focused on analysis and experiment of hot extrusion of aluminum and magnesium alloys, an extrusion die with an inclination angle leads to non- uniform velocity distribution at the cross-section of the die, and results in different strain and strain rate distributions. This kind of design can make the grain size at the material surface smaller and get a material with larger surface hardness. This study aims to conduct hot extrusion with different die inclination angles, and obtain a material with gradient micro-structures. At first, die with different inclination angles are designed, and the temperature at the die exit and effective strain, effective strain rate distributions are discussed using the finite element analysis. At last, aluminum and magnesium extrusion experiments are conducted and the micro-structures of the materials are observed to understand the effects of the die inclination angles at 15 degrees on the grain size distribution and hardness test at the cross-section of the material. The grain size is about 17.2£gm at around center of the cross-section and hardness is about 68.2HV. The smallest grain size is 4.1£gm at the edge of the cross-section and the highest hardness is 83.8HV.

Made available in DSpace on 2014-06-11T19:24:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-08-31Bitstream added on 2014-06-13T19:51:22Z : No. of bitstreams: 1 caceresbenitez_p_me_arafo.pdf: 539913 bytes, checksum: 4b2674880d3cfaa5af955bceb1ed75eb (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O objetivo desta pesquisa foi avaliar a influência de várias temperaturas sobre os valores de microdureza de topo e base de uma resina composta fotopolimerizável comercialmente disponível, variando o tipo de fonte de luz (LEDs e lâmpada halógena). As temperaturas testadas foram 25, 35, 45, 55, 65, 80, 90 e 100º C. A resina composta utilizada foi a Z100 (3M). Com o auxílio de uma matriz metálica foram confeccionados 3 corpos-de-prova de 2 mm de espessura e 9,8 mm de diâmetro para cada temperatura. Os corpos-de-prova foram polimerizadas LEDs (60 s) ou lâmpada halógena (40 s) enquanto eram submetidas às diferentes temperaturas, após a polimerização as amostras foram armazenadas a seco, em estufa a 37º C. Após 24 horas as amostras foram submetidas ao teste de microdureza Vickers no topo e na base. Baseados nos resultados conclui-se que com a elevação da temperatura aumentou o valor da dureza Vickers com correlação linear positiva e com ambos aparelhos; o valor da dureza de topo foi sempre superior à dureza de base independentemente da fonte de luz ou temperaturas empregadas; o aparelho de luz halógena só se mostrou superior à fonte de LEDs na região de base dos corpos-de-prova. / The aim of this research was to evaluate the influence of several temperatures on the microhardness values of top and base of a light curing composites resin commercially available, varying the type of light source (LEDs and halogen lamp). The tested temperatures were 25, 35, 45, 55, 65, 80, 90 and 100º C. The composite resin used was Z100 (3M). With the aid of a metallic mould were made three samples of 2 mm of thickness and 9,8 m diameter for each temperature. The samples were light cure while they where submitted to the different temperatures with LEDs (60 s) and halogen lamp (40 s), after the polymerization the samples were dry stored in a stove at 37º C. After 24 hours, the samples were submitted to the Vickers microhardness test in the top and in the base. Based on the results it was concluded that with the elevation of the temperature increased the Vickers hardness value with positive linear correlation on both devices. The hardness value of the top was always superior to the base hardness, independently of the light source or used temperatures. The halogen lamp source was superior to the source of LEDs in the area of base of the samples.

The diploma thesis deals with the influence of colouring additives and setting of the process parameters of 3D printing on the mechanical and surface properties of samples made of PLA material. The work describes the process of filament production, as well as the printing of normalized samples on a 3D printer using the additive method Fused Deposition Modeling. The impact of 3 types of colouring additives is evaluated on the basis of tensile test, hardness test and surface analysis. The evaluated quantities are primarily tensile strength, hardness, surface texture, roughness and corrugation. The work also evaluates the influence of the percentage of sample filling, the direction of the fibres of the inner filling and the orientation of the samples in the printing chamber of the 3D printer on the mechanical properties. The results are evaluated on the basis of the tensile test and the evaluated quantities are mainly the tensile strength, the ultimate stress and the modulus of elasticity in traction. The work is completed by evaluating the results and overall recommendations for filament manufacturers and users.

The geotechnical parameters of the different lithologies are of great importance regarding mining, infrastructures development and safety. The main aims of this thesis project are the evaluation of the previously acquired point load tests (PLT) data and the acquisition of a larger set for the various lithologies and alterations. In addition, the correlation to the Leeb Hardness test (LHT) method, and the determination of correlation factors (K) for estimating the uniaxial compressive strength (UCS) index from PLT data for various lithologies were evaluated. In total, 5236 previously PL tested samples, 1113 newly PL tested samples and 569 LHT measurements were obtained. The results showed that the highest values come from the footwall lithologies (Sp) ranging between 11-19 MPa, while the hanging wall lithologies (Qp) fall in range 10-14 MPa and the different ore types between 6-11 MPa. The correlation between PLT and LHT was poor, with the results completely overlapping for all country rock lithologies in the range 800-900 LHD, while the ore types fall in the range 600-700, and anhydrite at 500 LHD. On the other hand, the correlation factors K for the lithologies tested vary between 13-20 for the weaker and more altered rock types and 25-30 for the stronger ones, correlating well when compared to the actual UCS values found in the literature. In conclusion, it is evident that the LHT is not able to substitute the PLT as it captures different properties of the rock. The conversion from PLT to UCS gave rather accurate results, with slightly different correlation factors K for the tested lithologies.

Submitted by Eunice Novais (enovais@uepg.br) on 2018-07-31T14:08:13Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Julio Cezar C Filho.pdf: 2297707 bytes, checksum: 0318db2af277ea89875b724010007eb0 (MD5) / Made available in DSpace on 2018-07-31T14:08:13Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Julio Cezar C Filho.pdf: 2297707 bytes, checksum: 0318db2af277ea89875b724010007eb0 (MD5) Previous issue date: 2018-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Avaliou-se a influência do tipo e viscosidade da resina composta utilizada para reforço radicular (RR) em dentes com canais radiculares excessivamente alargados na adesão de pinos de fibra de vidro (PFV) ao canal radicular. Foram selecionados 78 dentes permanentes unirradiculares, os quais tiveram suas coroas removidas e suas raízes tratadas endodonticamente. Após uma semana, foi realizado o preparo dos condutos para posterior RR. Nesse momento, as raízes foram aletoriamente divididas em 6 grupos (n=13), sendo um grupo controle positivo (GCP – em que os canais não estavam alargados), um grupo controle negativo (GCN – em que os canais estavam alargados, porém sem RR), e 4 grupos de RR dos canais alargados de acordo com a combinação dos seguintes fatores: tipo de resina composta: bulk ou convencional e viscosidade da resina composta: fluida ou regular. Após a cimentação dos PFV, para cada raiz foram obtidas seis fatias (duas representativas de cada região radicular - terço coronário, médio e apical). Em seguida, para cada grupo, 7 raízes foram avaliados em resistência de união (RU) pelo teste de push-out, 6 raízes foram avaliados em nanoinfiltração (NI) e microdureza Vickers. Os dados obtidos de RU e NI foram submetidos a ANOVA dois fatores (grupo experimental vs região radicular) e Tukey (α=0,05), e de microdureza a ANOVA um fator e Tukey para cada grupo experimental (α= 0,05). Os grupos de RR com as resinas tipo bulk em ambas as viscosidades apresentaram resultados de adesão superiores estatisticamente ao GCN em todas as regiões radiculares (maior RU e menor NI). Pode-se concluir que a técnica de reforço radicular com resinas composta do tipo bulk, tanto com viscosidade regular quanto com viscosidade fluida, pode ser uma técnica alternativa interessante previamente à cimentação de PFV em raízes enfraquecidas com canais radiculares alargados. / The influence of the type and viscosity of the composite resin used for root reinforcement (RR) was evaluated in teeth with excessively wide root canals in the adhesion of glass fiber post (GFP) to the root canal. It was selected 78 uniradicular permanent teeth, which had their crowns removed and their roots treated endodontically. After one week, the conduits were prepared for later RR. At that time, the roots were randomly divided into 6 groups (n = 13): positive control group (PCG - where the root canals were not enlarged), negative control group (NCG - where the root canals were widened - but without RR), and 4 groups of RR of the widened root canals according to the combination of the following factors: type of composite resin: bulk or conventional and viscosity of composite resin: flow or regular. After the cementation of the GFP, six slices were obtained for each root (two representatives of each root region - coronary, middle and apical third). Then, for each group, 7 teeth were evaluated in bond strength (BS) by the push-out test, 6 teeth were evaluated in nanoleakage (NL) and Vickers microhardness (VHN). The data obtained from BS and NL were submitted to two-way ANOVA (experimental group vs root region) and Tukey (α = 0.05), and from VHN to one-way ANOVA and Tukey for each experimental group (α = 0.05). The RR groups with bulk composite resins at both viscosities showed statistically superior adhesion results to GCN in all root regions (higher BS and lower NL). It can be concluded that the radicular reinforcement technique with bulk composite resins, both with regular and flow viscosities, may be an interesting alternative technique prior to the GFP cementation in weakened roots with widened root canals.

AbstractAN IN-VITRO COMPARISON OF THE RETENTION OF PREFABRICATED PARALLEL-SIDED VENTED TITANIUM POSTS CEMENTED WITH THREE DIFFERENT DUAL-POLYMERIZABLE RESIN CEMENTSBy Maha M. El-Sayed, B.D.S., D.M.D.A Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University.Virginia Commonwealth University, 2003Thesis Director: David R. Burns, D.M.D. Associate Professor and Program DirectorGraduate ProsthodonticsDepartment of ProsthodonticsPurpose: The purpose of this in-vitro study was to compare the retentive strength of an autopolymerizing resin cement to three dual-polymerizable resin cements when used to cement paraposts without light activation and to relate diametral tensile stress and hardness as a measure of the degree of polymerization to the retentive strength of the different dual-polymerizable resin cements. Material and methods: 60 human extracted premolar teeth were endodontically-treated and randomly divided into 4 test groups (n=15). Parapost XP posts (size 5) were cemented using Panavia 21(control), Panavia F, RelyX Unicem and Linkmax resin cements. The latter three cements were dual-polymerizable and were not light-activated, and the control cement was autopolymerizable. Also, 140 resin cement samples were fabricated for diametral tensile stress and Knoop hardness testing. Each test had 70 samples, 10 of each of the following groups: Panavia 21, Panavia F light-activated, Panavia F autopolymerized, RelyX Unicem light-activated, RelyX Unicem autopolymerized, Linkmax light-activated, Linkmax autopolymerized. Post retention, diametral tensile stress and surface hardness tests were performed 1 week after sample fabrication or post cementation.Results: ANOVA and Tukey-Kramer statistical analysis revealed significant differences among the test groups for the three tests. Conclusions: Within the limitations of this in vitro study, tested dual-polymerization resin cements had similar or superior parapost retention to the control autopolymerizing resin cement without photoactivation. Dual-polymerizable resin cements had improved diametral tensile stress and surface hardness when light-activated than when autopolymerized. No correlation was observed between surface hardness and diametral tensile stress or between the tested physical properties of the resin cements and their retentive qualities

Cold metal forming processes have been widely used for manufacturing of their high production rates and increased yield strength after forming process. For the use in service, increased yield strength of the cold-formed products should be known. The new yield strength can be found by several methods. Mechanical tests such as compression or tensile test are direct methods to obtain new yield strength if the product shape is appropriate. Finite element simulations may be another way to get accurate results for new yield strength distribution. Also Vickers hardness number can be used for prediction of yield strengths by available conversion models. The aim of this study is to compare the results of all these methods. During the study two different materials (austenitic stainless steel and carbon steel) cold formed by drawing and extrusion are investigated. FE simulations have been conducted to predict product properties. For this purpose flow curves obtained from compression and tensile tests are used in FE-models based on elasto-plastic, isotropic hardening material. Results show that both materials are highly anisotropic and have much lower yield strength values than found in simulations. Similarly none of the models correlating Vickers hardness numbers and yield strengths are successful since they are designed for an isotropic hardening material. This study basically presents the deviation of a real material behavior from isotropic material behavior.