دورات هندسية

 

 

Materials (تصنيف المواد هندسيآ وأيضا انواع الروابط)

صفحة 2 من 4 الأولىالأولى 1 23 4 الأخيرةالأخيرة
النتائج 11 إلى 20 من 40
  1. [11]
    د.محمد باشراحيل
    د.محمد باشراحيل غير متواجد حالياً
    إستشاري الملتقى
    الصورة الرمزية د.محمد باشراحيل


    تاريخ التسجيل: Mar 2009
    المشاركات: 7,042
    Thumbs Up
    Received: 127
    Given: 15


    محاضرات مفيدة
    تم دمج المحاضرات 1-5 لتوحيد الموضوع


    0 Not allowed!



  2. [12]
    ahmed_ashmawy
    ahmed_ashmawy غير متواجد حالياً
    عضو فعال
    الصورة الرمزية ahmed_ashmawy


    تاريخ التسجيل: Nov 2008
    المشاركات: 113
    Thumbs Up
    Received: 0
    Given: 0
    شكرا جزيلا ولك كل التقدير

    0 Not allowed!



  3. [13]
    أحمد رأفت
    أحمد رأفت غير متواجد حالياً
    عضو متميز
    الصورة الرمزية أحمد رأفت


    تاريخ التسجيل: Mar 2007
    المشاركات: 524
    Thumbs Up
    Received: 11
    Given: 14

    materials6 المحاضرة السادسة (منحنيات التبريد Cooling Curve)

    Cooling Curve





    المحاضرة بالمرفقات

    وهى عبارة عن ملفات ويب من النت من جامعة
    Camberdge
    ويارب بكون بفيد

    0 Not allowed!


    الملفات المرفقة
    Eng.Ahmed Raaft
    مــصــــEGYPTـــــــر
    Mechanical Engineer

  4. [14]
    أحمد رأفت
    أحمد رأفت غير متواجد حالياً
    عضو متميز
    الصورة الرمزية أحمد رأفت


    تاريخ التسجيل: Mar 2007
    المشاركات: 524
    Thumbs Up
    Received: 11
    Given: 14

    materials7 المحاضرة السابعة (Phases & Iron-iron Carbon)

    Phase Diagrams
    هو رسم توضيحى لنسبة وجود الطور سواء صلب او سائل فى المادة مع تغير درجة الحرارة والضغط

    Important phase diagrams:
    1. To show what the phases are present at different composition.
    2. To indicate the temperature at which an alloy cooled under equilibrium condition starts to solidify.
    3. Identify the chemical composition and phase constituent of the alloy at a certain temperature
    4. Determine the degree of heat transformation rule to the case of fusion and vice versa.


    Binary Isomorphous Alloy Systems.

    وهوا خليط بين مادتين متجانسين
    ولكن يشترط أن يكون حجم الذرات لآيختلف بنسبة 15% و يكونو نفس الكفاؤة ونفس نوع التركيب البلورى


    Lever Rule
    Using the lever rule one can determine quantitatively the relative composition of a mixture in a two-phase region in a phase diagrame



    Types of reactions in Binary Phase Diagram






    Alpha


    Ferrite: the BCC iron crystal lattice, a 0.02 or 0.025% at 723, and to 0.005 or 0.008%.


    Austenite: austenite has an FCC crystal structure and much a higher solid solubility for carbon Ferrite. A maximum solid solubility of carbon is reaching 2.08% at 1148 , and decreasing to 0.8% at 723.


    Gamma


    Ferrite: ferrite has a BCC crystal structure. A maximum solid solubility of carbon is reaching 0.09% at 1465 .



    Cementite: is negligible solubility limits and a composition of 6.67% C and 93.3% Fe. Cementite is a hard and brittle compound


    Reaction in this phase diagrame





    مرفق ملف عنIron-IronCarbon
    ويارب بكون بفيـد

    0 Not allowed!


    الملفات المرفقة
    Eng.Ahmed Raaft
    مــصــــEGYPTـــــــر
    Mechanical Engineer

  5. [15]
    أحمد رأفت
    أحمد رأفت غير متواجد حالياً
    عضو متميز
    الصورة الرمزية أحمد رأفت


    تاريخ التسجيل: Mar 2007
    المشاركات: 524
    Thumbs Up
    Received: 11
    Given: 14

    materials 8المحاضرة الثامنة (المعاللجة اللحرارية Heat Treatment)

    Heat Treatment of Plain-carbon Steels


    Heat treatment is the process of controlled heating and cooling of metals to alter their physical and mechanical properties. It is often used to increase the strength of a material, but it can also be used to improve machining, (the quality of metal able to be used in machines,) formability, (the quality of metal to be easily shaped,) and ductility (ability of metal to be drawn into a wire).

    Time - temoerature transformer diagrame
    TTT
    This scheme to clarify the phase change with temperature and time to control the mechanical properties





    Martensite: if a sample of plain carbon steel in the austenitic condition is rapidly cooled to room temperature by quenching it in water. It’s the structure will be changed from austenite to martensite.

    Full Anneal: Is the process of slowly raising the temperature above the Austenitic Temperature line A3 (see the red arrow). Austenitic steel is the most ductile of the steels and has a very high relative strength. It is held at this temperature until all the material transforms and then slowly cools in a furnace to about 50 degrees Celsius when it can be then cooled through
    convection in the room.
    Normalizing: Is the same as the Full Anneal, the metal is heated above the A3 temperature line (see red arrow). However, the metal is cooled right away through room convection, rather than through a furnace. This makes normalizing cheaper since a furnace is not used to cool the metal in a controlled environment. Both of these processes make the metal more soft, which makes it more machineable, the difference is that the Full annealed metal is uniformly soft while the Normalized metal varies in its softness
    Process annealing: This is used to treat worked metals, such as two pieces of metal that have been welded together. This makes it possible for the metal to undergo further work without fracturing. The metal is heated to just below the A1 temperature line (see blue arrow); it is held there long enough for the metal to change the size and distribution of its grain structure and then cooled naturally in air. This process is cheaper than Full Annealing or Normalizing because the metal is not heated to high
    temperatures
    Tempering: This is used to remove brittleness found in quench hardened parts. It is done to improve hardness, ductility, toughness and strength. It must be done immediately after a metal has been quenched and then cooled to 40 degrees Celsius. It is then reheated to between 150-400 degrees Celsius. This heating is usually done in an oil bath; this ensures that every part of the metal will undergo the same temperature and tempering


    المحاضرة القادمة أنشاء الله سوف تكون
    Types of Plain-Carbon Steels

    ويارب بكون بفيد ويجعل هذا سبب لدخولنا الجنة بأذن الله

    0 Not allowed!


    Eng.Ahmed Raaft
    مــصــــEGYPTـــــــر
    Mechanical Engineer

  6. [16]
    د.محمد باشراحيل
    د.محمد باشراحيل غير متواجد حالياً
    إستشاري الملتقى
    الصورة الرمزية د.محمد باشراحيل


    تاريخ التسجيل: Mar 2009
    المشاركات: 7,042
    Thumbs Up
    Received: 127
    Given: 15
    مشكور مهندس أحمد رأفت
    محاضرات مباشرة ومفيدة ..

    بارك الله فيك وجزاك خيرا ً .. وجعل ذلك في موازين حسناتك
    وفقك .. وجعلك ناشرا للمعرفة..وتستحق تقييم..

    دمت بخير .. وكل عام وأنت بخير.

    0 Not allowed!


    "رَبِّ أَوْزِعْنِي أَنْ أَشْكُرَ نِعْمَتَكَ الَّتِي أَنْعَمْتَ عَلَيَّ وَعَلَى وَالِدَيَّ وَأَنْ أَعْمَلَ صَالِحاً تَرْضَاهُ وَأَصْلِحْ لِي فِي ذُرِّيَّتِي إِنِّي تُبْتُ إِلَيْكَ وَإِنِّي مِنَ الْمُسْلِمِينَ "

    { رَبَّنَا اغْفِرْ لَنَا وَلِإِخْوَانِنَا الَّذِينَ سَبَقُونَا بِالْإِيمَانِ وَلَا تَجْعَلْ فِي قُلُوبِنَا غِلّاً لِّلَّذِينَ آمَنُوا رَبَّنَا إِنَّكَ رَؤُوفٌ رَّحِيمٌ }

  7. [17]
    نسيم الفل
    نسيم الفل غير متواجد حالياً
    جديد


    تاريخ التسجيل: Sep 2009
    المشاركات: 2
    Thumbs Up
    Received: 0
    Given: 0
    السلام عليكم ورحمة الله وبركاته
    الموضوع جميل جداً

    أريد معلومات وصور توضيحية مفصلة عن البنية البلورية وعيوبها
    الرجاء ارسال المعلومات إلى [email protected]
    وشكراً

    0 Not allowed!



  8. [18]
    أحمد رأفت
    أحمد رأفت غير متواجد حالياً
    عضو متميز
    الصورة الرمزية أحمد رأفت


    تاريخ التسجيل: Mar 2007
    المشاركات: 524
    Thumbs Up
    Received: 11
    Given: 14
    ألف شكر للمهندس / محمد باشراحيل
    و للمهندس / نسيم الفل
    وبالنسبة للمهندس نسيم الفل لقد أرسلت لك البيانات المطلوبة

    0 Not allowed!


    Eng.Ahmed Raaft
    مــصــــEGYPTـــــــر
    Mechanical Engineer

  9. [19]
    أحمد رأفت
    أحمد رأفت غير متواجد حالياً
    عضو متميز
    الصورة الرمزية أحمد رأفت


    تاريخ التسجيل: Mar 2007
    المشاركات: 524
    Thumbs Up
    Received: 11
    Given: 14

    المحاضرة التاسعةMaterials9 (انواع الحديدوالكربون Plain Carbon Steel)

    PlainCarbonStell,Stainlesssteels &
    Cast Iron

    Plain-carbon steels types


    Low Carbon Plain-Carbon Steels


    The very low carbon steels have relative low strength but very high ductility. These steels are used for sheet metal for forming applications (such as Automobiles).As the carbon increase, the steel become stronger but less ductile. These generally contain less than about 0.25 wt% C and are unresponsive to heat treatments intended to form martensite. As a consequence, these alloys are relatively soft and weak, but have outstanding ductility and toughness; in addition, they are machinable, weldable, and, of all Steels, are the least expensive to produce. And sheets that are used in pipelines, buildings, bridges, and tin cans.



    Medium Carbon Plain-Carbon Steels (1020-1040)


    The medium-carbon steels have carbon concentrations between about 0.25 and 0.60 wt%. These alloys may be heat treated by austenitizing, quenching, and then tempering to improve their mechanical properties. Used for shafts and gears. Microstructures of tempered martensite.


    High Carbon Plain-Carbon Steels (1060-1095)


    The high-carbon steels, normally having carbon *******s between 0.60 and 1.4 wt%, are the hardest, strongest, and yet least ductile of the carbon steels. They are almost always used in a hardened and tempered condition and, as such, are especially wear resistant and capable of holding a sharp cutting edge. The tool and die steels are high carbon alloys, usually containing chromium, vanadium, tungsten, and molybdenum. These alloying elements combine with carbon to form very hard and wear-resistant. Are used for springs, die blocks, cutters, and
    shear blades



    Stainless Steels


    types of Stainless Steels


    Ferritic Stainless Steel


    Contain carbon above (0.1%).


    Contain chromium between (12-30% Cr).


    Uses as: - corrosion resistance and working in high temperature.



    Martensitic Stainless Steel


    Contain carbon between (0.15%-1%c).


    Contain chromium between (12-30% Cr).


    Very hard, high strength, high wear resistance, and Corrosion resistance of the relatively few other types.



    Austenitic Stainless Steel
    Contain (7%-20% Ni).


    Contain chromium between (16-25% Cr).


    High formability because has FCC.


    Weldability.




    Cast Iron


    Types Of Cast Irons


    White Cast Iron


    Structure: cementet + pearlite, and so there are no carbon-free.


    Usage: used for their excellent resistance to wear and abrasion, Industry balls mills and sewage pipes and used as a primary industry DUCTIL &



    MEALABLE CAST IRON.


    Disadvantage: brittle because the cementite.


    Advantages: very strong & high resistance to wear and abrasion.



    Gray Cast Iron


    Structure: GRAPHITE + PEARLITE or GRAPHITE + FERRITE.


    Usage: Rules machines (bed) & Bearings.


    Disadvantage: Brittle and the presence of cracks and low ductile.


    Advantages: Excellent vibration of damping capacity,


    امتصاص الذباذبات نظرآ لوجود الكربون على شكل شرائح (FLAKS)

    Good wear resistance, low cost & can produce high-precision castings.


    Circumflex after the break: Black or Gray.




    Ductile Cast Iron (nodular or spherulitic graphite cast iron)



    Ductile cast iron combines the processing advantages if gray cast iron with the engineering advantages of steel.


    Circumflex under the microscope: a white ground of the ferrite and ball black of carbon.


    Advantages: good fluidity & castability, excellent machinability & good wear resistance.


    High strength, ductility, toughness, hot workability, & hardenability.



    Mealable Cast Iron


    Mealable cast irons are first cast as white cast irons which contain large amounts of iron carbides and no graphite.

    ويتم أجراء عملية mealablzation وهى عبارة عن تسخين الى ساعات طويلة حتى يتم تكسير

    All casting is heated-treated.





    ويارب بكون بفيد
    وعلى فكرة انا مازلت طالب بالسنة الخامسة ميكانيكا تصنيع





    0 Not allowed!


    Eng.Ahmed Raaft
    مــصــــEGYPTـــــــر
    Mechanical Engineer

  10. [20]
    أحمد رأفت
    أحمد رأفت غير متواجد حالياً
    عضو متميز
    الصورة الرمزية أحمد رأفت


    تاريخ التسجيل: Mar 2007
    المشاركات: 524
    Thumbs Up
    Received: 11
    Given: 14

    materialsالمحاضرة العاشرة(Polymers)

    Polymers Materials


    Mean word the Polymer is latine word, consist of two parts, poly=many, mers=parts.


    A polymeric solid material may be considered to be one that contains many chemically bonded parts or units which themselves are bonded to form a solid.


    Advantages


    Minimum finishing, Good insulation, Light weight, Noise Reduction, low cost than metal, Insulated to electrical, no need to lubricant, can may produce multi color, Availability for manufacture.


    Disadvantages


    Low strength, No Available to high temperature, Exposure to broken and damaged, Adverse environmental impact in the case burning.



    Types of polymers: 1-Elastomers


    2-Plastic ( Thermoplastic & Thermosets )


    Thermoplastic: Can be reheated & formed.


    Thermosets: Can't reheated & formed.


    Polymerization
    •Chain growth polymerization: Monomers link together to form long chains (polymers)





    Vinyl and Vinylidene Polymers


    Vinyl polymers: One of the hydrogen atoms is replaced by another atom or group of atoms.


    Vinylidene Polymers: Both hydrogen on a carbon are replaced by another atom or group of atoms.


    Homopolymer and Copolymers:
    · Homopolymers: Polymer chain is made up of single repeating units (mers).
    Example: AAAAAAAA
    · Copolymers: Polymer chains made up of two or more repeating units.
    Random copolymers: Different monomers randomly arranged in chains.
    Example: ABBABABBAAAAABA
    Alternating copolymers: Definite ordered alterations of monomers.
    Example: ABABABABABAB
    Block copolymers: Different monomers arranged in long blocks.
    Example: AAAAA…….BBBBBBBB……
    Graft copolymers: One type of monomer grafted to long chain of another. AAAAAAAAAAAAAAA
    B B
    B B






    Industrial Polymerization Method.
    The basic raw materials which are used to produce the basic chemicals for polymerization process, such as natural gas, petroleum, and coal.
    These chemicals are then polymerized by many different processes into plastic materials, such as graduals, powders, or liquids which further processed into finish products.
    Some of the most important polymerization method.
    · Bulk Polymerization.
    · Solution Polymerization.
    · Suspension Polymerization.
    Emulsion Polymerization.


    ويارب اكون أفدتكم والمرة القادمة هى تكملة البوليمر


    ويارب اكون بفيدكم بشىء ننتفع بة
    ويدخلنا الجنـــة
    وأرجو من ألأدارة ضم باقى المحاضرات مع بعضها, وشكرآ ألف الشكر لها

    0 Not allowed!


    Eng.Ahmed Raaft
    مــصــــEGYPTـــــــر
    Mechanical Engineer

  
صفحة 2 من 4 الأولىالأولى 1 23 4 الأخيرةالأخيرة
الكلمات الدلالية لهذا الموضوع

عرض سحابة الكلمة الدلالية

RSS RSS 2.0 XML MAP HTML