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  1. FennLane

    How to get 356-T6 aluminum back to weak state?

    Its never a great idea to introduce a residual stress and then heat treat and expect the part not to move. The most significant residual stress will probably due to the quenching process involved in solution treatment and if this is the cause of distortion you may struggle. What are they like...
  2. FennLane

    Porsche 924 Rally Car set-up advice

    Why do you think understeer is slow on gravel - If you drive an car with understeer in the correct manner it can still be effective. Look at the old videos of Blomquist in a SAAB 96 V4. If you have been using an Imp for gravel rallies then you should know how to avoid issues with making the...
  3. FennLane

    End of Life - Fatigue

    I don't agree that the clock can be reset of defects are below a specified length. This assumes that you have studied the defect tolerance of the structure and understand the fatigue crack propagation. There is some confusion in the original post an that is whether or not the crane has been...
  4. FennLane

    Welding Aluminum to Steel

    I generally believe that the challenges this will create my become quite significant. I successfully friction welded Aluminium to both normal steel and stainless steel back in the early Seventies. To suggest that a 'glassy' film is produced due to melting the aluminium is not quite...
  5. FennLane

    Steel Bar (Rebar) Quality Problem

    What kind of Rebar as this may have a bearing on the problems you are having. Where do you buy our raw material and have you checked the stock you are using prior to rolling?
  6. FennLane

    Formulas for Tensile and Yield strength

    This all sounds a little strange and I have never heard anything like this in more than 40 years working as a Metallurgist 30 of which were spent making testing machines. Strain and elongation are essentially dimensionless so what do you mean by 'validate them'? Sounds like a Bulgarian...
  7. FennLane

    surface hardness

    Some idea of the shaft material would help along with the basic diameter of the shaft you are hardening.
  8. FennLane

    SAE 1020 and SAE 1008 material properties and stress/strain curve

    ...tensile stress. True Strain = ln(1+ engineering strain (At very low strain there is little difference) True Stress = Engineering Stress * (1 + True Strain) If you plot the results on a log/log graph you should obtain a straight line. The slope of this line 'n' would be the work...
  9. FennLane

    Growth due to Plasma Nitriding

    I am planning to make a small batch of close tolerance shafts from a 4340 VAR steel. The shafts will need significant machining on their ends and we plan to stress relieve at 630degC prior to grinding. Once ground we would like to Plasma Nitride the shafts (400 degC) and use them without...
  10. FennLane

    Very hard surface layer

    Once you have reached the quenching rate needed to produce a complete transformation to martensite it is unlikely that faster cooling rates will have any impact on hardness. The thermal capacity of the part will impact on the cooling rate needed for complete transformation as will the...
  11. FennLane

    Flow rate of lubrication system for gears

    The real issue with a splash lubricated gearbox will be the duration it has to run for and the power losses due to the mesh and windage. Yu need to think that the gears not only need lubrication but also cooling as will the bearings. I would try to budget for a minimum of 1% of the transmitted...
  12. FennLane

    Zincated Steel Sheets for the Casing of an AC Machine

    A 'zincate solution' in normally an alkali solution made from dissolving zinc, zinc oxide or zinc hydroxide and contain Zn(OH)42− anions which are known as tetrahydroxozincate. Gumm's Bondal for example contains this material and is commonly used as a preparation for chrome plating aluminium...
  13. FennLane

    Urgent question, Residual stress

    Frederick, I just don't believe you comments concerning the movement if voids and other crystal structure changes due to DCT and I have never seen a paper which was based on good science to explain these phenomena. Most diffusion processes are thermally activated so how can very low...
  14. FennLane

    Tensile Testing grips

    It would seem obvious that it is not sensible to try to lubricate the grip to testpiece interface. Your use of the term 'gall' indicates that adhesive wear was taking place and this is typical of the damage that occurs in wedge grips when the grip body to insert interface in not adequately...
  15. FennLane

    Bearing race case depth vs. strength under pressure

    How about a full complement needle roller?
  16. FennLane

    SS304 as brake disk material

    What kind of vehicle? Motorcycles and bicycles commonly use a stainless steel but they don't need the same heat capacity as those required for automobiles. I would also think that ferritic stainless steels may be more suitable than Austenitic grades which also work harden significantly. The...
  17. FennLane

    Tensile Testing grips

    I don't really agree that the coefficient of friction between the grip body and the wedge insert has any impact on gripping in the 'ideal' condition. Ideal would be a coefficient of 'zero' and the relationship between wedge angle and clamping force would correlate perfectly. Th greater the...
  18. FennLane

    Tensile Testing grips

    I don't quite understand why galling alone will make the test piece slip. Assuming you are using conventional wedge grips it is customary to lubricate the sliding faces with a Moly type grease to prevent this type of wear. If you do have damage to the back of the insert then re-grinding to...
  19. FennLane

    Flywheel Inertia with chamfer

    I am not trying to be silly but do you really think you can measure to the number of decimal places you are quoting. If you start by sensibly rounding the numbers you may discover it all becomes negligible. I spent years making rotating equipment test rigs and we never worried to the extent...
  20. FennLane

    "Ductility Test"

    I think 'ductility' testing is a relatively complex subject. 12% Elongation of a 4d gauge length is not a very impressive amount of ductility but would be useful to ensure that relatively high strength bolts were not brittle. A gauge length of 4 x Diameter would be considered relatively short...

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