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  1. Coctyle

    Historical grade specifications

    I have been looking for chemical specifications for steel grades from the early 20th century. Specifically, I want to know what the chemical analysis limits for 1020 steel were in about 1920. Same as today, or not? ASTM only lists old standards going back to about the '90s. I have found all...
  2. Coctyle

    PAGB Etch, Saturated aqueous picric acid with copper chloride

    How was it deliberately made to explode? Was it originally in solution, or just wet crystals? Maybe I shouldn't have said it is ridiculous to restrict it, but it is used in numerous etchants that are important to me. I have a little residual annoyance from working for an employer that would not...
  3. Coctyle

    Quench vs. Hydrogen Assisted Crack

    So, you saw the cracks before HT, or you did not? Or are these cracks not in an area where hot tears typically occur and therefore not checked before HT?
  4. Coctyle

    PAGB Etch, Saturated aqueous picric acid with copper chloride

    Has anyone on this forum ever heard of an accidental picric acid explosion in a metallurgical laboratory? I have not. Aqueous picric acid is perfectly safe. Moist picric acid crystals are perfectly safe. It has to dry out completely to be sensitive. It is ridiculous to restrict the use of...
  5. Coctyle

    Certain metals detectable by ground scan?

    Remember, the people who got rich in the gold rush sold shovels and other support items and services. Very few miners/panners made anything to speak of. So maybe the original poster and/or his dad, should go into the portable XRF business (of course, that is pretty well dominated by several...
  6. Coctyle

    Quench vs. Hydrogen Assisted Crack

    Is it correct that you do not know if the cracks existed before HT or not? Heating the part to the austenitizing temperature should allow hydrogen to diffuse out, therefore you would be unlikely to see HAC after HT unless, as someone alluded to already, the part was exposed to hydrogen after HT...
  7. Coctyle

    PAGB Etch, Saturated aqueous picric acid with copper chloride

    I have been using saturated aqueous picric acid with sodium dodecylbenzene sulfonate as the wetting agent to reveal prior austenite grain boundaries in heat treated steel. I have found that the addition of copper chloride is helpful (as described in Vander Voort's Metallography Principles and...
  8. Coctyle

    What is the bonding mechanism in Soldering and Brazing?

    Vacuum is not necessary if velocity is high enough. Are you familiar with cold spray coatings? Solid powder is accelerated to supersonic speed and plastically deforms on contact with substrate to form metallurgical bond without melting either material. Can be done with metals, ceramics...
  9. Coctyle

    Post-weld heat treat for part to be hardened after weld,

    mfgenggear: Thanks for the comment. Would the anneal have to be done before the part cools to room temperature to avoid cracking of hardened material? Does the AMS spec that you referenced specify that the anneal be done before the part cools below some specific temperature?
  10. Coctyle

    Post-weld heat treat for part to be hardened after weld,

    Thanks Maui. I had misinterpreted your earlier comment. I thought you meant after machining, to relieve stresses that might be induced by machining for instance.
  11. Coctyle

    Post-weld heat treat for part to be hardened after weld,

    MAui: Why would you say that an anneal would make sense if the part is going to be austenitized? Wouldn't that relieve residual stresses from machining? Or is there some other reason?
  12. Coctyle

    Post-weld heat treat for part to be hardened after weld,

    What about normalizing to refine grain structure in the weld zone? Is that suggested or necessary to achieve a consistent response from the quench and temper heat treatment?
  13. Coctyle

    Nitriding vs Corrosion resistance

    There are also tradenames such as BlackNitride and NiTemper, among others. BlackNitride, as the name implies, includes the black oxide step inherently. It is a salt bath process. NiTemper is a gas process and does not automatically include black oxide. Ask your "good" vendor about the process...
  14. Coctyle

    Post-weld heat treat for part to be hardened after weld,

    My company makes specialty hand tools. When possible, we weld together parts of standard tools. Most of the time, the material is 4140 and we heat treat it to somewhere between 40 and 50 HRC after welding. In the past, post-weld subcritical annealing has been done, probably due to a generic...
  15. Coctyle

    CrV steels in Chinese products

    MintJulep...I think you hit the nail on the head. tbuelna...Buying from Snap-on is excellent advice.
  16. Coctyle

    CrV steels in Chinese products

    tbuelna - Did I say that I had a problem with Chinese hand tools? No, I did not. I was just asking a technical question about material choice. Don't be so quick to get offended.
  17. Coctyle

    CrV steels in Chinese products

    Can anyone explain why so many Chinese products such as hand tools use CrV steels (variations of 6150)? There are less expensive alloys that are far superior when heat treated in the range of 45 HRC to 55 HRC. Is chromium less expensive in China? Really, why does anyone use 6150 for anything?

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