Yazar "Demir, B." seçeneğine göre listele
Listeleniyor 1 - 12 / 12
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Adhesive weld bonding of interstitial free steel at spot welding for automotive application(Redakcia Kovove Materialy, 2010) Hayat, F.; Demir, B.; Acarer, M.; Aslanlar, S.In this study, the effect of adhesive bonding on strength and strength-ductility behaviour of welding joint in electrical resistance spot welding of 7315 grade IF steel sheets was investigated. 7315 grade (DIN EN 10130-1999) IF steels were adhesively bonded and different welding current and welding cycle conditions were performed in welding process. For adhesive bonding, Loctite Terostat 9120-Grey and Terostat 9220-Black grade adhesive bonders were used. Additionally, adhesively bonded joint samples were also performed without welding. Microstructure and tensile-shear tests of the adhesively bonded and welded materials were evaluated. Failure modes of the weld bonded tensile sheared samples were observed to be different from only welded samples. Experimental results have shown that with the increase in the weld time and weld current, the effect of the adhesive weld bonding on tensile performance also increases.Öğe Effect of aging temperature and martensite by volume on strain aging behaviour of dual phase steel(Taylor & Francis Ltd, 2008) Guenduez, S.; Demir, B.; Kacar, R.A study has been made of the cold deformation aging susceptibility of dual phase steel with 14 and 22% martensite by volume. It was found that yield strength (YS) and ultimate tensile strength (UTS) increased with increasing testing temperature up to 200 degrees C and then decreased at 250 degrees C which indicated that static strain aging is dominant up to 200 degrees C. This aging is associated with free dislocations in the ferrite as a result of the austenite-martensite transformation, which become preferential sites for solute atom diffusion. At higher temperature (250 degrees C) a softening effect is dominant due to tempering of martensite. It was also observed that at a given aging temperature YS, UTS and Delta Y (increase in stress due to strain aging) increased with by volume of martensite.Öğe The effect of cutting parameters on cutting force during the processing of inconel 718 super alloy(2007) Tasliyan, A.; Acarer, M.; Seker, U.; Gökkaya, H.; Demir, B.In this study, the effects of cutting parameters such as cutting speed, feed rate and cutting depth over cutting forces have been investigated. For this purpose, nickel based super alloy Inconel 718 has been processed with ceramic cutting tool having 1.2 mm insert radia on a digitally controlled turning lathe (CNC) without using cooling water. Different cutting processes having the values of five different cutting speeds (225, 300, 350, 400, 500 m/dak) and five different feed rates (0.05, 0.075, 0.1, 0.125, 0.15 mm/rev) and two different cutting depths (1mm, 2mm) have been implemented. In the experiments, the lowest main cutting force was obtained as (A-1-V) 192 N in 500 m/min cutting speed, 0.05 mm/rev feed rate speed and 1 mm depth of cut, the highest main cutting force was obtained as (B-5-I) 780 N in 225 m/min cutting speed, 0.15 mm/rev feed rate speed and 2 mm depth of cut.Öğe Effect of Weld Currents on Microstructure, Corrosion Behavior of AZ31 Magnesium Alloy(Springer Science and Business Media Deutschland GmbH, 2021) Demir, B.; Koç, E.; Saud, A.N.Resistance spot welding (RSW) of magnesium alloys is very attractive due to not require filler metal. AZ31 Mg alloy sheets were exposed to RSW by constant weld electrode pressure, constant weld times, and numerous weld currents. The potentiodynamic polarization technique was used for the investigation of the corrosion behavior of the alloys. Results showed that the dendritic structure was promoted at the weld zone. AZ31 base metal is more resistant to corrosion than welded alloys. However, when compared with each other, icorr values of the welded alloys decrease as a function of weld current increases. The corrosion rate was predominantly influenced by the distribution of intermetallic and alloying elements, and RSW weld varied, which was in response to altering the joint microstructure. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature.Öğe Effect of weld time and weld current on the mechanical properties of resistance spot welded IF (DIN EN 10130-1999) steel(Redakcia Kovove Materialy, 2009) Hayat, F.; Demir, B.; Acarer, M.; Aslanlar, S.In this study, the effects of weld current and weld time on the tensile peel strength and tensile-shear strength of 7114 grade IF (Interstitial Free) steel sheets joined by spot welding were investigated. Weld processes were performed by using 3, 5, 7, 9 kA weld current and 5, 10, 15, 20, 25, 30 weld cycles. The microstructure of the welded materials was evaluated. The hardness profiles were also determined. Experimental results showed that tensile shear loading bearing capacity and hardness of both weld and heat affected zones increased for increasing weld time and weld current. Weld nugget diameter extended by increasing weld time or/and weld current, so tensile shear load bearing capacity and tensile peel strength increased. Tensile fracture behaviour of the samples was evaluated. Weld lobe was constructed with respect to weld current and time.Öğe Effect of weld time and weld current on the mechanical properties of resistance spot welded IF (din en 10130-1999) steel(2009) Hayat, F.; Demir, B.; Acarer, M.; Aslanlar, S.In this study, the effects of weld current and weld time on the tensile peel strength and tensile-shear strength of 7114 grade IF (Interstitial Free) steel sheets joined by spot welding were investigated. Weld processes were performed by using 3, 5, 7, 9 kA weld current and 5, 10, 15, 20, 25, 30 weld cycles. The microstructure of the welded materials was evaluated. The hardness profiles were also determined. Experimental results showed that tensile shear loading bearing capacity and hardness of both weld and heat affected zones increased for increasing weld time and weld current. Weld nugget diameter extended by increasing weld time or/and weld current, so tensile shear load bearing capacity and tensile peel strength increased. Tensile fracture behaviour of the samples was evaluated. Weld lobe was constructed with respect to weld current and time.Öğe The hardenability of austenite with different alloy content and dispersion in dual-phase steels(2008) Demir, B.; Erdogan, M.In this investigation, two steels with different chemical compositions were used to study the hardenability of austenite with different alloy content and dispersion in dual-phase steel. The results showed that ferrite carbide aggregate did not form and considerable amount of the austenite present at the intercritical annealing temperatures transformed to martensite even at the cooling rate of 0.01 °C/s (furnace cooling) in the specimens. In dual-phase steels the absence of the carbide formation is unusual at this cooling rate and the critical cooling rates for the martensite formation is so low, compared to the previous studies. It is concluded that without a high quenching power, these steel compositions are suitable for industrial production of dual-phase steel through continuous annealing line of iron and steel plants. © 2008 Elsevier B.V. All rights reserved.Öğe The influence of the austenite dispersion on phase transformation during the austempering of ductile cast iron having a dual matrix structure(2008) Erdogan, M.; Kilicli, V.; Demir, B.In the present work, an unalloyed ductile cast iron containing 3.50 C wt.%, 2.63 Si wt.%, 0.318 Mn wt.% and 0.047 Mg wt.% was austempered for various times at both the conventional austenitizing temperature (single phase austenitic region) and the different intercritical austenitizing (partially austenitizing) temperature ranges to investigate the effect of parent austenite dispersion at the austenitizing temperature on the nature of austenite decomposition during austempering. A microstructure map was created to illustrate the transformation of products quantitatively as a function of austempering time for a particular austenitizing temperature and austempering time. It was concluded that in addition to proeutectoid and bainitic ferrite, the new ferrite (also called epitaxial ferrite) introduced into the partially austenitized structure during austempering and new ferrite formation and its content was dependent on the scale of the parent austenite dispersion at the austenitizing temperature, variation in austenitizing temperature and austempering time. The new ferrite formed only in the structure with coarse parent austenite dispersion. © Carl Hanser Verlag GmbH & Co. KG.Öğe An investigation on the production of dual-phase steel from AISI4140 and its impact strength at different martensite volume fractions(2007) Demir, B.In this study, production of dual-phase steel from AISI 4140 steel having 0.44% C, 0.35% Si, 0.71% Mn, 1.13% Cr, 0.17% Mo and its impact strength at different martensite volume fractions (MVF) are determined. Dual-phase steel production is accomplished by intercritically annealing at intercritical temperatures (? + ? region, between 740°C and 795°C) and then by water quenching. By doing so, change in the MVF with intercritical annealing temperature (ICAT) of AISI 4140 steel is controlled. 743°C and 748°C are decided as ICAT for producing dual-phase steel impact test specimens with different MVF. For comparison, impact tests are also carried out on as-received, quenched, quenched-tempered and normalized specimens. Results show that dual-phase steel having min MVF manifests considerable higher impact energy than all the specimens except for that of the samples quenched-tempered. As a result, dual-phase microstructure produced from AISI 4140 increased the toughness significantly.Öğe An Optimization Study on Resistance Spot Welding of DP600 Sheet Steel via Experiment and Statistical Analysis(Dr D. Pylarinos, 2023) Alzahougi, A.; Demir, B.; Elitas, M.Resistance Spot Welding (RSW) is widely used in many automotive, boiler, and ship manufacturing industries. Therefore, the optimization and effectiveness of the RSW process are very useful and cost-efficient processes in addition to improving weld quality. This study used various welding parameters to investigate the optimization of the RSW process of Advanced High Strength Steel (AHSS). RSW was carried out using different welding times, currents, and electrode pressure values. Microstructural analysis, nugget formation, and tensile shear test were performed on samples. This study applied the Taguchi method and ANOVA to set up the welding process and optimize its results. Microstructural characterization showed that the weld nugget microstructures had a high-volume fraction of martensite. Using the Minitab software, Taguchi (DOE) and ANOVA on the tensile shear test results showed that welding current is more effective than clamping pressure on the tensile shear load-bearing capacity (TLBC). However, clamping pressure affects the weld current effects on weld performance. Additionally, the TLBC of RSW samples increases, whereas increasing the clamping pressure leads to a decrease in TLBC and nugget dimensions. Consequently, a detailed analysis of the RSW coefficients and their effects led to optimized results. © 2023, Dr D. Pylarinos. All rights reserved.Öğe Tensile shear stress and microstructure of low-carbon dual-phase Mn-Ni steels after spot resistance welding(Springer, 2007) Hayat, F.; Demir, B.; Acarer, M.Tensile shear stresses and microstructure of dual steels with different volume fractions of martensite are studied after spot resistance welding. A Mn-Ni low-carbon steel heated in the intercritical temperature range and cooled in water and in air is studied. Spot resistance welding of test pieces is performed for different times at constant welding pressure and peak value of the welding current. The microstructure of the welded specimens is investigated and their permissible tensile shear stresses are determined.Öğe Transformation characteristics of ductile iron austempered from intercritical austenitizing temperature ranges(2009) Erdogan, M.; Kilicli, V.; Demir, B.In the present work, the transformation characteristics of ductile iron austempered from intercritical austenitization temperature ranges were investigated. For this purpose, an unalloyed ductile cast iron containing 3.50 wt% C, 2.63 wt% Si and 0.318 wt% Mn were intercritically austenitized (partially austenitized) at various temperatures and then rapidly transformed to a salt bath held at the 365 °C for austempering for various times to produce dual matrix structure with different ausferrite volume fractions in ferrite matrix. A microstructure map was created to illustrate the transformation of products quantitatively as a function of austempering time for a particular intercritical and austempering heat treatment temperature and time. It was demonstrated that the total volume fraction of transformed phases was approximately constant for all austempering times after rapidly transforming samples from a particular intercritical temperature to austempering temperature. It was found out that the new ferrite (It is also called epitaxial ferrite) introduced into the intercritically austenitized structure during austempering and its content was dependent on the intercritical austenitizing temperature and austempering time. © 2006 Springer Science+Business Media, LLC.
