توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱The influence of pulsed – TIG welding on the strength of Al–6Mg alloy
نویسنده(ها): ، ،
اطلاعات انتشار: هفتمین همایش انجمن هوافضای ایران، سال
تعداد صفحات: ۵
In order to evaluate the influence of pulsed current on the welded–joint strength, pulsed–TIG process was used to weld the A1–6Mg alloy is used strongly in aerospace structures. High strength of this alloy is dun to work hardening during manufacturing and existence of precipitates in its microstructure. During pulzed–TIG welding of this alloy, the effect of Time Ratio was studied on the welded–joint strength. To reach the maximum strength, Time Ratio had an optimum value which was equal to 1.6. At this Time Ratio the finest and the most uniform microstructure in the weld metal was achieved.<\div>

۲Effect of repair–welding parameters on life time of die casting moulds
نویسنده(ها): ، ، ،
اطلاعات انتشار: اولین کنفرانس بین المللی و هفتمین کنفرانس ملی مهندسی ساخت و تولید، سال
تعداد صفحات: ۸
In die casting, H13 hot working tool steels are exposed to heat shocking and cracking due to the thermal fatigue which is exerted by die casting process. The gradual destruction of mould surfaces during the service, decreases casting piece quality and limits the mould life time. These moulds are expensive and replacing of them is the main problem of the die casting industries therefore repair–welding of die casting moulds can be helpful. H13 steel has low weldability because of the significant hardening resulted from large amounts of alloying elements. Within this study, results were obtained on the performance of repair welded parts that were welded by three types of filler metals on the thermal fatigue test. The filler metals that are used in this study are H13 tool steel, maraging steel and Co–base alloy. Maximum and minimum life time of the repair welded parts of die casting mould in the thermal fatigue test were obtained from Co–base alloy and H13 hot work steel filler metals, respectively. Repair–welding by maraging filler metal shows the intermediate life time. It seems that repair–welding of H13 moulds by maraging filler metals is more economic because of its lower price in comparison with the Co–base filler metal.<\div>

۳Friction Stir Welding of AZ31 Magnesium Alloy
نویسنده(ها): ، ، ،
اطلاعات انتشار: اولین کنفرانس بین المللی و هفتمین کنفرانس ملی مهندسی ساخت و تولید، سال
تعداد صفحات: ۶
Friction stir welding (FSW) is a novel solid–state welding process for joining metals and alloys. This process is based on inserting a rotating tool to the weld seam. The evolved frictional heat and heavy plastic strains on materials adjacent to the rotating tool as well as traversal tool movement result in joining. Apparently, fusion welding of magnesium alloys is accompanied with occurrence of defects such as gas porosities and oxide inclusions that are as a result of very reactive nature of magnesium in the liquid state. Defect–free joining of AZ31 magnesium alloy by means of FSW process was the object of the present work. According to the results, sound weldments for AZ31 can be resulted by choosing appropriate welding parameters. However, FSW of AZ31 leads to a decrease in the hardness of the stir zone and the transitional zone with respect to the base metal.<\div>

۴a comparison of laser and resistance spot welding of steel sheets fatigue lives and residual stresses
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۸
this study addresses the results of a comparison of laser spot welding and resistance spot welding regarding to residual stresses and fatigue performance of spot joints inoverlapped steel sheets experimental and numerical studies were conducted to characterize laser and resistance spot welds to gain an understanding of load carrying capacity under static and cyclic loading temperature distributions and residual stress states of different joint geometries used in automotive industry experimental and numerical results revealed different failure types with different fatigue lives of the laser and resistance spot welds it was found out that the weld region in LSW has been surrounded by a compressive region which has higher compressive stress values and bigger size than of resistance spot welds.<\div>

۵effect of heat flux models on temperature distribution and fluid flow during gas tungsten arc welding
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۹
a three dimensional model is developed to predict temperature distribution and fluid flow during gas tungsten arc welding in order to analyze the influence of heat flux model on the geometrical appearance of weld pools and temperature distribution two types of heat sources with different natures based on gaussian surface heat flux and volumetrica goldak's double ellipsoid heat flux distributions are employed then these heat flux schemes are implemented into the model for simulation of GTA welding of AA1050 using FLUENT –CFD software the transient temperature distribution and temperature variations during welding for each heat flux model are predicted.<\div>

۶effect of laser welding conditions on properties of steel tailor welded blanks TWB
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۷
there is a major interest to manufacturers of automobile and aerospace parts towards the tailor welded blanks TWBs to reduce the weight and cost of the parts and improve their perfomance in this work effet of laser welding parameters such as power speed angle of the laser beam and the focused length on properties of four groups of TWBs two groups with similar thickness and different steels and two groups with similar steel and different thicnesses are investigated the results indicate that the inclined laser beam cause the sample failure from the weld zone in the tensile test setting the focal poit on the top surface of the sheets results in better properties in compariston to the other positions due to high cooling rate at weld zone microstructure of the weld aminly consists of acicular ferrite widmanstatten ferrite allotropic ferrite and to some extent low carbon bainite which in turn lead to higher strength in welded sheets comparing to the as received ones<\div>

۷effect of welding parameters on microstructure and mechanical properties in dissimilar friction stir welding between magnesium and aluminum alloys
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۷
dissimilar friction stir welding FSW between magnesium alloy AZ31 and aluminum alloy 1100 plates with 3 mm thickness was studied . Fusion welding of aluminum \magnesium alloys has failed because of forming much more intermetallic compounds by using FSW the amount of intermetallic compounds significantly reduced in this study different samples obtained by employing rotating speeds ranging from 300 to 1000 rpm and welding speeds ranging from 10 to 50 mm\min. the welds were also formed when the stirring pin was off the centerline to AZ31 OR TO Al1100 . mechanical properties of the joints were evaluated by means of hardness and tensile tests at room temperature. microstructure of the welds was examined by using opticalmicroscope and x–ray diffractometer.<\div>

۸evaluation of the effect of welding parameters on the residual stresses in dissimilar welding of high strength steels
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۸
for many years the use of high strength steels in consturction is increasing due to high ratio of strength to weight and cost considerations these properties reduce the fabrication cost and time to make use of these advantages of these modern steels their weldability was extensively evaluated in the present study a dissimilar patch welds between two high strength steels was investigated a series of dissimilar steels joints based on the S600MC as the base plate and s355 as the patch plate were produced using robotic MIG welding residual stresses were determined using the x–ray diffraction XRD the effect of welding speed and sequence on residual stresses distribution in two different patch shapes was studied analysis of the results revealed that using of the welds in opposite directions reduces the welding stresses and the effect of welding speed is different in two pathc shapes.<\div>

۹effect of thermal cycles and peak temperature on microstructure and toughness properties of reheated heat affected zone
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۹
the influence of real and simulated thermal cycles with secondary peak temperatures on the properties and microstructure of the reheated coarse grained heat affected zone CGHAZ in X80 high –strength low –alloy HSLA steel has been investigated. Four wires tandem submerged arc welding TSAW process with different heat input was used to generate real double passes thermal cycles the simulated cycles involved heating ti the first peak temperature Tp1 of 1400 C and then reheating to different secondary peak temperatures Tp2 of 700,800 and 900 C with cooling rates of 3.75 and 2 C\S the toughness of the simulated reheated CGHAZ was assessed using charpy impact testing at 0 and –50 C the microstructure and microhardness of the real and simulated specimens were investigated.<\div>

۱۰interfacial microstructure and properties of SiC\SiC joint brazed with Ag–Cu–Ti alloy
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۴
SiC CERAMIC WAS JOINED TO ITSELF USING ACTIVE brazing alloys like Ti in shape of sheet filler of Ag–cu and Ti–6AI –4V. This operation is occurred in an inert gas furnace interfacial microstructure studied with scanning electron microscopy and X–ray diffraction variation of electrical specific resistance measured by 4 pin astute multimeter and strength of these joint was measured by fracture shear loading this joint is happened at 900 c and upper temperature with 90 minutes and upper time electrical specific resistance goes upper with joint in low temperature & time but this variation is very little . the microstructure showed and excellent bonding at the interfaces. the data showed also that the joining of the SiC decreases with increasing temperature and time.<\div>

۱۱influence of friction stir welding parameters on mechanical properties of aluminum tailor welded blanks with different thickness ratios
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۶
welded sheets with different thicknesses are one of the major kinds of tailor welded blanks TWB which are widely used in metal forming industries . In the present work effects of friction stir welding FSW parameters and thickness ratios on mechanical properties of thin aluminum tailored sheets are studied thickness ratios for these set of welded blanks are 1,1.33 and 1.67 .quality size and shape of stirred zone were studied by metallographic examination of weld nuggets results indicate that increasing the welding rotational speed rpm with a constant weldeing traverse speed v cm\min leads to increase of the nugget size and decrease of the defects.<\div>

۱۲investigation on the SSC resistance of the API 5L–X70 weld metals with different amount of acicular ferrite
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۶
different amounts of acicular ferrite were constructed in the microstructure of API 5L–X70 submerged arc welds using varous amounts of titanium addition , sulfide stress cracking resistance of these welds was evaluated in hydrogen sulfide environments the results showed that increased acicular ferrite percentage of the weld improves workability of the weld metal in sour medium the internal investigations confirmed that the NACE failure criterion was adequate for detection of the weld cracks bainite and martensite –austenite microconstituents were detrimental for sour service application.<\div>

۱۳incorporation of friction stir processing into surface modification of polymeric materials
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۸
engineering polymers are being increasingly used in a wide number of applications related to tribological properties many chemical and physical methods have been utilized to modify polymer surfaces by depositing thin inorganic films most of these techniques are baed upon the use of high energy sources that ultimately can damage polymer surfaces either chemically or physically incorporation of fillers as reinforcing materials significantly changes various properties of thermoplastics friction stir processing FSP is a tool to modify the surface properties of materials. it has been developed for upper surface modification of metals in recent studies exclusively by making surface composites however it has never been used for modification of polymers.<\div>

۱۴mictostructure and failure behavior of resistance spot welded of dissimilar steel sheets HSLA and st12
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۹
high –strength low alloy HSLA E275 developed specifically for automotive application due to its excellent formability and low weight on the other hand the resistance spot weld of dissimilar materials is generally more challenging than of similar materials due to difference in the physical chemical and mechanical properties of the base metals the influence of the primary welding parameters affecting the heat input such as current and time on the morphology fracture mode microhardness and tensile shear bearing capacity of dissimilar welds between HSLA E275 steel and ST12 steel in two different thicknesses 1.2mm has been investigated in this study.<\div>

۱۵performance of aluminothermically welded wide –gap rails
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۱۰
the wide –gap aluminothermic rail welds with root opening of 50–70 mm were produced using the plain carbon steel rail and the non–alloy aluminothermic charge such process can repair the defective rails each with only one wide gap weld instead o fusing a relatively long plug rail and two standard welds. the corresponding equipment including the sand molds the crucible and the self –tapping thimble were designed mechanical properties and micro –structure of the welds and of the heat affected zone HAZ of the rails as well as the impact energies and the fracture toughness of the welds were investigated . the wide gap aluminothermic rail welds exhibited yield strength and tensile strength somewhat lower than those of the rail and the respective strengths of the HAZs failure happened in the weld center for a tensile specimen that included both the weld and the HAZ of the weldment.<\div>

۱۶spot welding parameters optimization for economic design and improving mechanical properties
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۶
spot welding of two incongruent high strength steel with different thickness was studied in an attempt to optimize welding condition the evaluated parameters consist of electrode force welding current and welding time which are more efficient on welding properties and economical aspect the selection of material and thichness of the sheets are exactly according to joining conditions in peugeot 206body central composite design CCD methodology has been used to arrange the experimental runs for peel test of weld in order to maximize weld strength and also minimize the operational cost a central composite theree factors in five levels was employed to evaluate the effects of electrode force F=420,432,450,468AND 480 dN welding time t=15.20.25.30and 35cycle and welding current C=11.7,12.5,13.7,14.9 and 15.7KA on mechanical welding properties.<\div>

۱۷welding characteristics of ultrahigh strength steel in annealed and quench–tempered conditions
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۸
in this research the welding characteristics a new UHSLA steel 35NiCrMoV123 have been studied in two general conditions annealed & quench –tempered carbon equivalent value of 35NiCrMoV123 steel is near 0.9 which classifies it as a very difficult to weld steel the effects of welding heat treatment cycle preheat interpass post heat on metallurgical and mechanical properties of weldments have been investigated by tensile impact toughness and hardness tests as well as optical microscopy observations it has been observed that by employing high temperature stress relief 600 C welding could be performed in annealed condition success fully .<\div>
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