Sökning: "Hot cracks"

Visar resultat 1 - 5 av 47 avhandlingar innehållade orden Hot cracks.

  1. 1. Closed-die forging and slab hot rolling with focus on material yield : some industrial problems analysed by FEM

    Författare :Esa Ervasti; Ulf Ståhlberg; Hans Keife; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material yield; Closed-die forging; Hot rolling; Cracks; Macro-inclusions; Steel; FEM; Industrial engineering and economy; Industriell teknik och ekonomi;

    Sammanfattning : The thesis is focussed on improving the material yield in closed-die forging and rolling. The former is restricted to the manufacturing of heavy crown wheels and front axle beams and the latter to the hot rolling of steel slabs. To enhance the yield the commercial FE-codes Form2D and Dyna3D are used. LÄS MER

  3. 2. Hot Cracking and Grain Boundary Weaknesses of Nickel - Based Superalloys

    Författare :Joel Håkan Andersson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hot cracks; Notch rupture testing; Eutectic; Weldability; Varestraint testing; Grain boundary weaknesses; Superalloys;

    Sammanfattning : Abstract Grain boundary weaknesses of nickel-based superalloys not only materialize during service in the hot turbine engine sections but also during the weld manufacturing. The performance, in this respect, of the most commonly used alloys at Volvo Aero Corporation (VAC), 718 and the higher temperature capacity Waspaloy, are therefore the main subjects for this thesis. LÄS MER

  4. 3. On the hot crack formation during solidification of iron-base alloys

    Författare :Karin Hansson; KTH; []
    Nyckelord :hot cracking; hot tearing; cracking fracturing ; tearing; ductility; brittleness; embrittlement; fractures; ductile brittle transition; solidification; iron; copper; nickel; Invar; steels; free machining steels; stainless steels; penetration; crack;

    Sammanfattning : Hot cracking during solidification is a severe problem inmany casting processes, for example in continuous casting.Combinations of low strength and low ductility of the materialat high temperatures and applied tensile stress can cause hotcracking. LÄS MER

  5. 4. Life Prediction and Mechanical Behavior of Thermal Barrier Coatings

    Författare :Yan Liu; Materialteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Stress intensity factors; Macro-cracks; Micro-cracks; Mechanical behaviour; Thermal barrier coatings; Life prediction; Material technology; Materiallära; materialteknik;

    Sammanfattning : Delamination and spallation of thermal barrier coating (TBC) systems, used in hot parts of gas turbines, have been studied with respect to thermal fatigue. TBCs with and without pre-existing cracks were investigated. Thermal shock tests were performed until coating spallation. LÄS MER

  7. 5. Microstructure and Properties of Additively Manufactured Tool Steels for Hot Stamping

    Författare :Miwen Yuan; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tool Steels; Wear; Hot stamping; Additive Manufacturing; Softening Resistance;

    Sammanfattning : Hot work tool steels are commonly used to produce dies for hot stamping, where the steels are exposed to cyclic thermal and mechanical loads. There is a constant demand to improve the lifetime of the dies. Additive manufacturing (AM) provides new solutions for tool design. LÄS MER