Implant Test And Acoustic Emission Technique Used To Investigate Hydrogen Assisted Cracking In The Melted Zone Of A Welded Hsla-80 Steel [uso Del Ensayo De Implante Y La Tecnica De Emision Acustica Para Estudiar El Agrietamiento Asistido Por Hidrogeno En La Zona Fundida En La Soldadura De Un Acero Hsla-80]

Weld metal hydrogen assisted cracking was studied using two flux cored wire (AWS E 70T-5 and AWS E 120 T5-K4) and a mixture gas of CO2 + 5% H2 to induce high values of diffusible hydrogen in high strength low alloy steel (HSLA-80) weldments. An Acoustical Emission Measurement System (AEMS) RMS voltmeter was coupled to the implant test (NF 89-100) apparatus to determine energy, amplitude and event numbers of signal. All cracks were initiated in the partially melted zone and propagated into the coarse-grained region of the heat affected zone when E 70 T5 consumable was used, and the quasi-cleavage fracture mode was predominant. When E 120 T5 K4 consumable was used the cracks propagated vertically across the fusion zone, and a mixed fracture mode was the most important. A significant relationship between acoustic emission parameters and fracture modes was found.354233241Vuick, J., (1992) Weld. World, V31 (5), pp. 308-321Svensson, L.E., (1994) Control of Microestrutures and Properties in Steel Arc Welds, pp. 39-44. , The ESAB Group. Esab AB. Gotherburg (Suecia). CRC Pres, IncBeachem, C.D., (1972) Metall. Trans., 3 (2), pp. 437-451Yurioka, N., Suzuki, H., (1990) Int. Mater. Rev., 35 (4), pp. 217-249Gedeon, S.A., Eagar, T.W., (1990) Weld. J., pp. 213s. , junioFang, C.K., Kannatey-Asibu E., Jr., Barber, J.R., (1995) Weld. J., pp. 177-184. , junioTrevisan, R.E., Ferraresi, A.V., Abstracts of Papers (1998) 79th Am. Weld. Soc. Annual Meeting (EE.UU.), p. 151. , 26-30 abrilCarpenter, S.H., Smith D.R., Jr., (1990) Metall. Trans. A, 21 A, pp. 1933-1938. , julioFals, H.C., Trevisan, R.E., (1998) Proceedings. 17th Int. Offshore & Arctic Engineering Conference, , Lisboa (Portugal), 5-9 julio(1986) Standard Methods for Determination of the Diffusible Hydrogen Content of Martensitic, Bainitic, and Ferritic Steel Weld Metal Produced by Arc Welding, , 17 p(1982) Cold Cracking Test Methods Using Implants, , Abril 10 pMota, J.M.F., Apps, R.L., (1982) Weld. J., pp. 222s. , juli

Effects Of Nitrogen And Pulsed Mean Welding Current In Aisi 316 Austenitic Stainless Steel Solidification Cracks [efecto Del Nitrógeno Y La Corriente Media Pulsada De Soldadura En La Formación De Grietas De Solidificación En Aceros Inoxidables Aisi 316l]

An analysis of the influence of nitrogen concentration in the weld zone and the pulsed mean welding current in the solidification crack formation is presented in this paper. The AISI 316L austenitic stainless steel was employed as the metal base. The welding was done using CC+ pulsed flux cored arc welding process and AWS E316LT-1 wire type. The tests were conducted using CO2 shielding gas with four different nitrogen levels (0, 5, 10 and 15 %) in order to induce different nitrogen weld metal concentrations. The pulsed mean welding current was varied in three levels and the Transvarestraint tangential strain test was fixed of 5 %. The results showed that the solidification cracking decreased as the pulsed mean welding current increase. It was also verified that an increase of the weld zone nitrogen level was associated with a decrease in both the total length of solidification crack and the amount of δ ferrite.384256262Fredriksson, H., (1972) Metall. Trans., 3, pp. 2989-2997Padilha, A.F., Guedes, L.C., (1994) Aços Inoxidáveis Austeníticos. Microestrutura e Propriedades, , Hemus Editora Ltda, São Paulo, BrasilFolkhard, E., (1988) Welding Metallurgy of Stainless Steels, , Springer-Verlag Wien, New York, EE.UUSuutala, N., Takalo, T., Moisio, T., (1980) Metall. Trans., 11 (A), pp. 717-725Suutala, N., Takalo, T., Moisio, T., (1979) Metall. Trans., 10 (A), pp. 1183-1190Lothongkum, G., Viyanit, E., Bhandhubanyong, (2001) J. Mater. Process. Technol., 110, pp. 233-238Backman, A., Lundqvist, B., (1977) Weld. J., JANUARY, pp. 23s-28sKearns, J.R., (1985) J. Mater. Energy Syst., 7, pp. 16-26Rabensteiner, G., (1985) Weld. World., 23, pp. 26-34Baeslack W.A. III, Savage, W.F., Duquete, D.J., (1979) Weld. J., MARCH, pp. 83s-90sOgawa, W., Murata, K.A.S., Tsunetone, E., (1980) J. Jpn. Weld. Soc., 49, pp. 564-571Klimpel, A., Mazur, W., Szymanki, A., (1979) Przegl. Spawalnictwa., 31 (6), pp. 9-12Zhitnikov, N.P., (1981) Weld. Prod., 28 (3), pp. 15-17Vitek, J.M., Dasgupta, A., David, S.A., (1983) Metall. Trans., 14, p. 1833Lundin, C.D., Chou, C.P.D., Sullivan, C.J.H., (1980) Weld. J., AUGUST, pp. 226s-232sBernstein, A., Areskoug, M., (1971) Aust. Weld. J., SEPTEMBER, pp. 84-87Arata, Y., Matsuda, F., Saruwatari, S., (1974) Trans. JWRI., 3 (1), pp. 79-88Kotecki, D.J., (1978) Weld. J., pp. 109s-117sHammar, O., Svensson, U., (1979) Solidification and Casting of Metals, pp. 401-410. , The Metals SocietyVarol, I., Baeslack, W.A., Lippold, J.C., (1997) Mater. Characterization, 39, pp. 555-57

Influence Of Flux Cored Pulsed Arc Welding Process In Solidification Cracking Susceptibility Of Austenitic Stainless Steel [influencia Do Processo De Soldagem Com Arame Tubular Pulsado Na Suscetibilidade A Trincas De Solidificação Em Aços Inoxidáveis Austeníticos]

This study presents an experimental evaluation of the influence of both pulsed and conventional welding currents on the formation of solidification cracks when using flux-core arc welding. The AISI 316L austenitic steel was employed as the base metal in the experiments. The welding was carried out by the FCAW process using CO2 as shielding gas and AWS E316L T-1 as a tubular wire. Pulsed and conventional welding currents were applied with three different levels: 150, 200, 250A. The Transvarestraint Test with three different tangential strain levels (1,3 and 5 %) was used for the evaluation of the solidification cracks. The results showed that the Total Crack Length (TCL) was consistently the highest when the conventional welding current was applied. Weld beads obtained with greater currents presented more of δ Ferrite formation and incurred in lesser Total Cracking Sizes. Was also observed that the Total Crack Size was independent of the current type and the current level when the higher tangential strain levels were used.11197101Konosu, S., (2001) Engineering Failure Analysis, 8, pp. 75-85Folkhard, E., (1988) Welding Metallurgy of Stainless Steels, , Springer-Verlag Wien New YorkSuutala, N., Takalo, T., Moisio, T., (1979) Metallurgical Transactions A, 10 (A), pp. 1183-1190. , AugustSuutala, N., Takalo, T., Moisio, T., (1980) Metallurgical Transactions A, 11 (A), pp. 717-725. , MayLourencato, L.A., Braga, E.M., Trevisan, R.E., (2001) 1° Congresso Brasileiro de Engenharia de Fabricação (COBEF), , Abril, Curitiba, Parana, BrasilOlson, D.L., (1985) Welding Journal, 64, pp. 281s-295s. , OctoberMohandas, T., Madhsudhan, R.G., (1997) Journal of Materials Processing Tecnology, 69, pp. 222-226Lothongkum, G., Viyanit, E., Bhandhubanyong, (2001) Journal of Materials Processing Technology, 110, pp. 233-23

Susceptibility To Hydrogen-induced Cracking In H2s Corrosion Environment Of Api 5l-x80 Welding Metal

The susceptibility to hydrogen-induced cracking in hydrogen sulphide (H2S) environment of welded API X80 steel was studied. The flux-cored arc welding process was employed with E71-T1 and E71-T8K6 wires. The welding parameters were kept constant, but the samples were welded using different preheat temperatures (room temperature and 100°C). The gapped bead-on-plate (G-BOP) test was used. The specimens of modified G-BOP tests were exposed to an environment saturated with H2S, as recommended by the NACE TM0284 standard. The weld beads were characterized by optical microscopy and the level of residual hydrogen in the samples was measured. The fracture surface areas of hydrogen-induced cracking were calculated and the fracture mode was discussed. It was found that the preheating temperature of 100°C was enough to avoid cracking, even in the presence of H2S. It was also found that the E71-T8K6 wire was more susceptible to cracking, and the typical mixed-mode fracture was predominant in all samples. © 2011 Taylor & Francis.25294100Natividad, C., Salazar, M., Contreras, A., Albiter, A., Pérez, R., Gonzalez-Rodriguez, J.G., (2006) Corrosion, 92, pp. 375-382Cooper, R., Silva, J.H.F., Trevisan, R.E., (2004) Rev Metal Madrid, 40, pp. 280-287Liu, S., Bracarense, A.Q., (1994) Soldagem E Materiais, 2, pp. 18-32Davidson, J.L., (1995) Mater Forum, 19, pp. 35-51Fals, H.C., Trevisan, R.E., (1999) Rev Metal Madrid, 35, pp. 233-241Chattoraj, I., Tiwari, S.B., Ray, A.K., Mitraj, A., Das, S.K., (1995) Corros Sci, 37, pp. 885-896Atkins, G., Thiessen, D., Nissley, N., Adonyi, Y., (2002) Weld J, 81, pp. s61-s68Silva, J.H.F., (2005) Teses De DoutoradoFaculdade De Engenharia Mecânica, , São Paulo, Brasil: Universidade Estadual de CampinasIto, Y., Bessyo, K., (1968), IIW DOC IX-576-68Miller, D.K., Hietpas, J., Depue, R., (2002) Weld J, 81, pp. 40-45(1996), p. 12. , National Association Corrosion Engineers. Houston, USA. NACE TM 0284, NACE InternationalFals, H.C., Trevisan, R.E., (1999) J Braz Soc Mech Sci, 21, pp. 675-682Chakravarti, A.P., Bala, S.R., (1989) Weld J, 68, pp. s1-s8Oliveira, S.P., Miranda, P.E.V., (2001) Revista Matéria, 5, pp. 1-14Yurioka, N., Suzuki, H., (1990) Int Mater Rev, 35, pp. 217-25

Preparation of silica with controlled pore sizes for enzyme immobilization

A simple method for the preparation of silica with controlled pore size, for use as a support for the immobilization of enzymes, is described in this article. Using sodium silicate and hydrochloric acid, a microporous silica was obtained that was then submitted to a hydrothermal treatment, resulting in macroporous silica suitable for enzyme immobilization. Suitability of the macroporous silica as a support depends on the method chosen for its preparation, which will determine pore volume and the effect of hydrothermal treatment on pore size. The pore volume of the support was 0.8-0.9 cc/g and the average pore size, controlled by the hydrothermal treatment, was in the range of 16 to 75 nm. The enzyme amyloglucosidase was used for the immobilization studies.7177Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Preparation of silica with controlled pore sizes for enzyme immobilization

A simple method for the preparation of silica with controlled pore size, for use as a support for the immobilization of enzymes, is described in this article. Using sodium silicate and hydrochloric acid, a microporous silica was obtained that was then submitted to a hydrothermal treatment, resulting in macroporous silica suitable for enzyme immobilization. Suitability of the macroporous silica as a support depends on the method chosen for its preparation, which will determine pore volume and the effect of hydrothermal treatment on pore size. The pore volume of the support was 0.8-0.9 cc/g and the average pore size, controlled by the hydrothermal treatment, was in the range of 16 to 75 nm. The enzyme amyloglucosidase was used for the immobilization studies.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Proposal Of A New G-bop Test To Evaluate Cracks In Weld Beads In Thin Sheets

The objective of the present work is the evaluation of a proposal for a gapped bead-on-plate (G-BOP) test, used for study of hydrogen cracks in relatively thin sheets of welded steel. That new proposal consists of the replacement of the usual solid blocks by an assembly of blocks in such a way that the test can evaluate weld beads on thin sheets. Student t distribution is applied to examine the functionality of the proposed test. Weld metals were deposited with flux-cored wires E71T-1 and E71T8-K6, with diameters of 1.6 and 1.7 mm, respectively, under two different preheating temperatures. Metal susceptibility to hydrogen cracking was evaluated by the presence and percentage of cracks in the weld metal. In order to evaluate and verify the functionality of the new G-BOP test proposal, the following were examined: efficiency of the new test in inducing hydrogen cracks in the weld metal, result replicability, fracture modes present in cracks, and the cooling rate imposed on the welding zone. Results showed that the new G-BOP test proposal is viable; results were replicable and the test was efficient in inducing cracks in weld metal with a confidence of 90%. © ASM International 2008.917480Tsuboi, K., Yatabe, H., Yamada, K., Hydrogen induced cracking in high strength steel (1996) Mater. Sci. Technol., 12, p. 400Yurioka, N., Suzuki, H., Hydrogen assisted cracking in C-Mn and low alloy steel weldments (1990) Int. Mater. Rev., 35 (4), pp. 217-252Graville, B.A., McParlan, M., Weld metal cold cracking (1974) Met. Construct. Feb, 6 (2), pp. 62-63McParlan, M., Graville, B.A., Development of the G-BOP test for weld metal cracking (1975), 12. , IIW, Doc. n. IX-922Atkins, G., Thiessen, D., Nissley, N., Adonyi, Y., Welding process effects in weldability testing of steel (2002) Weld. J., 11, pp. 61s-68sDavidson, J.L., Hydrogen-induced cracking of low carbon - Low alloy steel weldments (1995) Mater. Forum, 19, pp. 35-51Montgomery, D.C., (1996) Design and Analysis of Experiments, p. 428. , 4th edn Wiley, New YorkAdonyi, Y., (2000) Weldability of High Performance Steels, Conference Proceedings, Steel Bridge Design and Construction for the New Millennium With Emphasis on High Performance Steel, , http://www.nabro.unl.edu/articles/20002012/download/Adonyi1.pdfSilva, J.H.F., Proposal of a New Test to Evaluate the Susceptibility of Weld Metals to the Hydrogen Induced Cracking Phenomenon in Different Environments (2005), Ph.D. Thesis, State University of Campinas, Campinas-SP, BrazilChakravarti, A.P., Bala, S.R., Evaluation of weld metal cold cracking using the G-BOP test (1989) Weld. J., 1 (SUPPL.), pp. 1-s-8-sLinnert, G.E., (1994) Welding Metallurgy - Carbon and Alloy Steels, p. 176. , 4th edn American Welding Society, Miami, FLBeachem, C.D., A new model for hydrogen-assisted cracking (hydrogen embrittlement) (1972) Metall. Trans., 3, pp. 437-45