راهنمای عملیات حرارتی آلیاژهای غیرآهنی- آلومینیوم و آلیاژهای آن Heat Treaters Guide

Heat Treater's Guide Nonferrous Alloys Wrought Aluminum and Aluminum Alloys

راهنمای عملیات حرارتی آلیاژهای غیرآهنی- آلومینیوم و آلیاژهای آن

ABSTRACT

3003 Aluminum: Microstructures. (a) 3003-0 sheet, annealed. Longitudinal section shows recrystallized grains. Grain elongation indicates rolling direction, but not the crystallographic orientation within each grain. Polarized light. Barker's reagent. 100x. (b) 3003-0 sheet, annealed. Same as adjoining microstructure, but shown at a higher magnification. Dispersion of insoluble particles of (Fe,Mn)Als (large) and aluminum-manganese-silicon (both large and small) was not changed by annealing.

 

ساخت پودرهای فلزی توسط الکترولیز

Forming metal powders by electrolysis

ساخت پودرهای فلزی توسط الکترولیز

ABSTRACT

Fossil fuels will eventually be replaced by renewables. Currently, the most feasible and efficient way of utilising renewable energy is to convert it to electricity. In response to this change, fossil energy-based pyrometallurgical processes will inevitably shift to electricity driven processes. This chapter considers the feasibility of direct conversion of mineral to metal powder using a new electrochemical method, the FFC Cambridge process. The discussion will be on the background of electrometallurgy and powder metallurgy, the principles of the new process and its application for metal powder production, and the direct route from oxide precursors to alloyed powders.

 

اثر سرعت جوشکاری بر تنش پسماند در طول جوشکاری قوس با الکترود تنگستن تحت پوشش گاز

Influence of welding speed and power on residual stress during gas tungsten arc welding (GTAW) of thin sections

with constant heat input: A study using numerical simulation and experimental validation

اثر سرعت جوشکاری و توان بر تنش پسماند

در طول جوشکاری قوسی الکترود تنگستن (GTAW) مقاطع نازک با ورودی گرمای ثابت

مطالعه ای با استفاده از شبیه سازی و اعتبارسنجی تجربی

ABSTRACT

The temperature distribution and residual stresses for a GTAW circumferential butt joint of AISI 304 stainless steel using numerical simulation have been evaluated. For evaluation of weld induced residual stresses, the analysis of heat source fitting was carried out with heat inputs ranging from 200 to 500 J/mm to arrive at optimal heat input for obtaining proper weld penetration and heat affected zone (HAZ). For this chosen heat input, the influence of different weld speeds and powers on the temperature distribution and the residual stresses is studied. The heat source analysis revealed the best choice of heat input as 300 J/mm. The residual stresses on the inner and outer surfaces, and along the radial direction were computed. Increase in temperature distribution as well as longitudinal and circumferential residual stresses was observed with the increase in weld speed and power. The validity of the results obtained from numerical simulation is demonstrated with full scale shop floor welding experiments.

 

رفتار سینترینگ و خواص دی الکتریکی سرامیک ها

Sintering behavior and dielectric properties of BaTiO3 ceramics with glass addition for internal capacitor of LTCC

رفتار سینترینگ و خواص دی الکتریکی سرامیک های BaTiO3 با افزودنی شیشه برای خازن داخلی LTCC 

ABSTRACT

The addition effects of ZnO–B2O3–SiO2 (ZBS) glass on both the sintering behavior and dielectric properties of BaTiO3 were investigated in developing low-temperature-fired BaTiO3-based ceramics for LTCC devices. X-ray diffractometer (XRD), scanning electron microscopy (SEM), and a dilatometer were used to examine the effect of ZBS glass on BaTiO3 densification and the chemical reaction between the glass and BaTiO3. The results indicate that ZBS glass can be used as a sintering aid to reduce the sintering temperature of BaTiO3 from 1300 to 900 ◦C without secondary phase formation. The dielectric properties of BaTiO3 with ZBS glass sintered at 900 ◦C show a relative density of 95%, a high dielectric constant of 994, and a dielectric loss of 1.6%.

 

انتقال حرارت و رفتارانجماد پوسته‎ای در قالب ریخته‎گری پیوسته

Heat Transfer and Deformation Behavior of Shell Solidification

in Wide and Thick Slab Continuous Casting Mold

انتقال حرارت و رفتار تغییرشکل انجماد پوسته‎ای در ورق بزرگ و ضخیم قالب ریخته‎گری پیوسته

ABSTRACT

The shell solidification in continuous casting mold is a rather complex process that is coupled with thermal and mechanical behaviors, which are related to numerous of defects occurring in slabs surface and subsurface during practical continuous casting. Intending to increase the understanding of shell thermal and mechanical behaviors in continuous casting molds to improve the casting process, numerous studies[1-13] have been conducted over the past few decades by numerical simulation. However, among these previous studies, most of the mathematical models neglected the effects of mold flux film on shell heat transfer[1-6,11] or assumed that the mold flux film distribution in shell/mold gap was uniform or changed linearly with the mold height[7-10,12,13]. It is obvious that the assumptions did not conform to the actual case of practical continuous casting that the mold flux film in mold distributes dynamically both along mold height and circumference with the evolutions of shell/mold gap and shell temperature, and affects the shell thermal and mechanical behaviors greatly.

مشخصه‎های ضخامت پوسته در ورق تولید شده به روش ریخته‎گری مداوم

Characteristics of shell thickness in a slab continuous casting mold

مشخصه‎های ضخامت پوسته در ورق تولید شده به روش ریخته‎گری مداوم 

ABSTRACT

It is of great importance to form a thick and sufficiently uniform solidifying shell in the mold to prevent breakout in the continuous casting process. Breakout starts to take place at the thinnest point commonly, and therefore, it is significant to investigate the slab thickness distribution in longitudinal and transverse directions to determine this point. Experimental and numerical simulations are the two ways for  measurement of shell thickness in the mold. The former such as adding sulfur into the mold [1], disturbs the normal production and obtains some useful data, which cannot characterize the shell thickness profiles thoroughly. On the other hand, several scholars have researched the flow, heat transfer, and solidification in the mold by numerical simulation . However, some profound researches on the characteristics of the shell thickness have been done.

  

آنالیز اشعه ایکس Ti-Nb-Ta-Zr در آلیاژهای تیتانیوم

In situ X-ray analysis of mechanism of nonlinear

super elastic behavior of Ti–Nb–Ta–Zr system beta-type titanium alloy

for biomedical applications

آنالیز اشعه X در جای مکانیسم‌ رفتار سوپرالاستیک غیر‌خطی سیستم Ti-Nb-Ta-Zr

در آلیاژهای تیتانیوم نوع بتا برای کاربردهای زیست‌پزشکی

ABSTRACT

Ti–XNb–10Ta–5Zr (mass %) alloys based on nominal compositions of Ti–35Nb–10Ta–5Zr, Ti–30Nb–10Ta–5Zr, and Ti–25Nb–10Ta–5Zr were fabricated through powder metallurgy and forging and swaging processes for biomedical applications. The tensile deformation mechanisms of the Ti–25Nb–10Ta–5Zr, Ti–30Nb–10Ta–5Zr, and Ti–35Nb–10Ta–5Zr alloys were investigated in situ by X-ray diffraction analysis under several loading conditions.

Under the loading conditions, the X-ray diffraction peaks of all the specimens shifted to higher angles than those obtained under the unloading conditions. For the Ti–30Nb–10Ta–5Zr alloy, the elastic deformation is considered to progress continuously in a different crystal direction although after the elastic strain reaches elastic limit in the crystal direction where the elastic limit is the smallest, slip deformation occurs in that crystal direction. The elastic modulus of this alloy appears to decrease in terms of strain over the proportional limit. Thus, the elastic deformation behavior of the Ti–30Nb–10Ta–5Zr alloy does not obey Hooke's law.

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