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    Inherent Processing in Service Defects

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    randz8
    This document discusses different types of discontinuities in materials: inherent, processing, and service discontinuities. Inherent discontinuities form during solidification or casting and include porosity and inclusions. Processing discontinuities occur during manufacturing through processes like rolling, extrusion, machining, forging, and heat treatment, and can result in cracks, scratches, or laminations. Service discontinuities relate to how the material is used and includes corrosion, fatigue from repeated loading, wear, overload, and brittle or ductile fracture.

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    Inherent Processing in Service Defects

    Uploaded by

    randz8
    130 views13 pages
    This document discusses different types of discontinuities in materials: inherent, processing, and service discontinuities. Inherent discontinuities form during solidification or casting and include porosity and inclusions. Processing discontinuities occur during manufacturing through processes like rolling, extrusion, machining, forging, and heat treatment, and can result in cracks, scratches, or laminations. Service discontinuities relate to how the material is used and includes corrosion, fatigue from repeated loading, wear, overload, and brittle or ductile fracture.

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    Inherent Processing in Service Defects

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    This document discusses different types of discontinuities in materials: inherent, processing, and service discontinuities. Inherent discontinuities form during solidification or casting and include porosity and inclusions. Processing discontinuities occur during manufacturing through processes like rolling, extrusion, machining, forging, and heat treatment, and can result in cracks, scratches, or laminations. Service discontinuities relate to how the material is used and includes corrosion, fatigue from repeated loading, wear, overload, and brittle or ductile fracture.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    130 views13 pages

    Inherent Processing in Service Defects

    Uploaded by

    randz8
    This document discusses different types of discontinuities in materials: inherent, processing, and service discontinuities. Inherent discontinuities form during solidification or casting and include porosity and inclusions. Processing discontinuities occur during manufacturing through processes like rolling, extrusion, machining, forging, and heat treatment, and can result in cracks, scratches, or laminations. Service discontinuities relate to how the material is used and includes corrosion, fatigue from repeated loading, wear, overload, and brittle or ductile fracture.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    of 13

    INHERENT PROCESSING IN SERVICE DEFECTS

    Discontinuities
    A break or gap Lack of continuity

    Types of Discontinuities
    I. Inherent Discontinuities
    They can form during the solidification of ingots or during melting, casting and solidification of metal later in the fabrication process. Ex. CASTINGS

    II. Processing Discontinuities


    Occurs during manufacturing process Ex. Rolling, Extrusion

    III. Service Discontinuities


    - related to the various service conditions to which the material is subjected. Fatigue cracks, Corrosion, Stress Corrosion crack

    Inherent Discontinuities

    A. Casting Process & Defects


    Method of forming metal objects of complex shapes is by pouring molten metal into mould In which it sets to the required shape.

    o Porosity o Blowholes o Piping o Inclusions o Sponginess o Shrinkage o Hot tears o Crack o Cold Shuts o Unfused Chaplet o Misplaced core o Segregation

    Processing Discontinuities

    A. Rolling
    The flattening of metal between rollers is used for the production of strip, sheet, plate, bar and sections.

    o Spalling of the ball

    oTwo sites of a corrosion rash on the race of the outer ring.

    o Crack of the inner ring

    o Local wear of the inner ring corrosion

    o Pitting on the ball

    o Laminations

    B. Extrusion
    Similar to squeezing toothpaste from a toothpaste tube. The raw material is a heated cast billet of the required metal.

    o Surface Scratch

    o Part Scratch

    o Part Dent

    o Internal Cracking

    o Center Burst

    C. Finishing / Machining
    Machining is a shape-producing process in which a power-driven device causes material to be removed in chip form. Machine tools has been assigned to that group of equipment designed to hold a cutting tool and a work piece and establish a suitable set of motions between them to remove materials from the work in chip form.

    TEAR

    Grinding - crack

    D. Forging Process
    Is the working of metal into a useful shape by hammering or pressing and is the one oldest of the metal forming processes. Most of forging operations are carried out hot, although some metals are cold-forged. This method of shaping is therefore used in the manufacture of parts requiring good mechanical properties. Forging is a metal forming process used to produce large quantities of identical parts, as in the manufacture of automobiles, and to improve the mechanical properties of the metal being forged, as in aerospace parts or military equipment.

    a. Lap

    b. Burst c. Crack

    E. Heat Treatment
    Heat treatment is a method used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve a desired result such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering and quenching. It is noteworthy that while the term heat treatment applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding. Quenching Crack - A fracture, often termed a hardening crack, which arises from thermal stresses induced during rapid cooling.

    Service Discontinuities

    Material In Service Fail Due to:


    1. Corrosion
    Revert back, its natural state of iron oxide other revert to sulfides and oxides or carbonates

    2. Fatigue
    Repeated loading and unloading over prolong periods

    3. Wear 4. Overload
    Removal of material from contacting surfaces by mechanical action Faulty design, extra loads applied

    5. Brittle & Ductile Fracture


    Fracture preceded by a significant amount of plastic deformation is known as ductile fracture otherwise it is brittle fracture

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