Jump to content

mete

Members
  • Content Count

    335
  • Joined

  • Last visited

Community Reputation

0 Neutral

Profile Information

  • Location
    New York State
  1. My purpose here is to educate and destroy myths. When you hammer metal you don't make grains smaller you just distort them . You don't 'pack' the atoms closer you actually increase the volume since you create dislocations. Engineers are sometimes criticized for being very picky about terminology But I'd like all of you to understand exactly what the process is and use the right terms so everyone understands.
  2. Fowler does not deal with science ! ...When we go from austenite to pearlite/martensite or go in the opposite direction grains are first nucleated then grow . Points of nucleation are often grain boundaries .There is physically more room in grain boundaries for things to happen and things [various elements like V or bad guys like phosphorous] collect there. The atomic lattice when disturbed has what are called dislocations .These too are nucleation points both from an energy standpoint and because of the increased spacing between atoms...So - the more nucleation points [finer grain to start with] martensite, cold work , the more nucleation points -and that results in more and finer grains. We go back and forth across the transformation getting finer grain each time !! When we finally get to the hardening stage the final grain size is then dependent on the austenitic grain size at that point.
  3. Don't use the word 'packing' it's a MYTH !! As you drop below the austenite range you get either pearlite [slow cool] or martensite [fast cool]. Sam , you need to do more reading !!
  4. Well I was thinking of steels like 1095 where it might be significant and there is a diminishing returns thing as far as fine grain goes.. Of course in many aspects of life I could say that if you haven't made the point after three tries ,don't go further you'll only make a fool of yourself . ....Matt, this is all about nucleaton and grain growth. Normalizing gives you a certain number of nucleation sites ,quenching would give you more .Cold working in the pearlite range would give you more also.
  5. The process dissolves the carbides without going to higher temperatures .The higher temperatures are good to avoid as they mean grain growth. Multiple normalizing also means smaller grains since each time you go through the austenite/pearlite change you create new [small] grains. Quenching will give smaller grains as the energy in the martensite gives more sites for nucleating new grains. More than 3x creates other problems you don't want.
  6. mete

    6150?

    Yes that would be the only American steel that would have Cr and V .
  7. mete

    6150?

    Gall is the proper spelling and galling is cold welding of two parts rubbing against each other. I don't think galling is the appropriate term for the grinding problem......Somewhere deep in my memory I remember that our bayonets where once made of 6150.
  8. Sam , those are super sources for you and others !! Put them on a CD a read again and again.
  9. Niko, I understood your goal but to vary temperature would educate you more !! ..... You start out with ferrite and carbides in annealed steel . The purpose of soaking is to dissolve the carbides and diffuse the carbon throughout the matrix. Some carbides like iron carbide are easy to dissolve and diffuse but others like vanadium carbide are difficult to dissolve and diffuse and require longer times and higher temperatures !!
  10. If you do that test but for temperature [ keep one time but with different temperatures ] you will learn how much more critical is the temperature !!!
  11. mete

    Bug

    Here's a bumblebee on periwinckle.
  12. While there are always things in the History Channel that make me cringe the recent program on Medieval times was absolutely terrible .Very disjointed and many mistakes . I turned it off .The Vikings even had horns on their helmets !!!
  13. Yes Fe+C is steel but I should have clarified that I meant ONLY Fe+C not with any other alloying element ......Yes with thin layers the time it takes to diffuse through a layer is shorter.......
  14. Pascal is the guy who invented the triangle !!
×
×
  • Create New...