Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Recent content by MagBen

  1. MagBen

    Fatigue damage and heat treatment

    yes, re-heat could make it worse. practically i agree with what Ed suggests to prohibit re-heat to re-use. My previous opinion was more of theoretical[bigears]
  2. MagBen

    Fatigue damage and heat treatment

    Macro cracks/voids are unlikely to be eliminated. micro fatigue cracks (unlike corrosion cracks) can be potentially healed by heat treatment. 1. stress relief, can help to reduce the likelihood of further cracking. 2. Fatigue cracking can create grain boundaries that are not aligned properly...
  3. MagBen

    1215 Hot Rolled vs Cold Rolled

    Like genetic austenitic stainless, this alloy is considered "not heat treatable", Q&T is unlikely to get you martensite. However, some sorts of heat treatment may get you a smaller grain size, which can bring you a higher yield strength per the Hall-Petch relationship. otherwise you will need...
  4. MagBen

    Magnetic Flux

    oops, Mike's formular is for Br, not Bdi. my apologies.
  5. MagBen

    Magnetic Flux

    Mike offered a simple, practical approach to measure Br, but it is under quite a few conditions: 1. it is for high coercivity magnet, with close to rectangular/square hysteresis loop. 2. two poles, magnetized straight through, 3. consistent cross-section. using HH coils, or a single search...
  6. MagBen

    electro magnet

    so sounds like you wanted some dirty and cheap soft magnetic material. try any low carbon steels 1002, 1005, 1008, 1010 ...whatever you can find. keep in mind, carbon very much affects permeability, the less the better. also do a stress relief anneal if material experienced significant...
  7. MagBen

    forge bar and rolled bar

    if the last deforming temp and reduction are the same I do not see much difference on mechanical properties. hte big difference is rolling is one dimensional (only increasing length no much on width), while forge is two dimensional, and so a forged bar is more uniform in micros and mechanicals.
  8. MagBen

    Alloy 718 - Api 6a cra / B637 - ams)

    Technically (not representative of a quality engineer) 718 can and is being used for oil & gas applications still meeting the maximum hardness requirements of the NACE, but normally with less Nb addition and a higher temperature heat treatment for a better corrosion and a bit compromised strength.
  9. MagBen

    electro magnet

    Remelting scrap sheet metal apparently no issue melting iron and silicon powder could have issue. using VIM for example the powder could have magnetic coupling issue. Limiting the addition of powder amount within 50% could solve the problem. but why you need powder, why not buy some Fe and Si...
  10. MagBen

    Failure analysis of a thin-walled tube

    have you ever "seen" MnS, or just speculate based on high Mn and S contents from EDX? if the former, are they taken a form of elongated inclusions? MnS can act as macro-voids or micro-cracks. MnS inclusions can also promote HIC. If all these are true, it seems to me cracks initiate around the...
  11. MagBen

    Steel - Hardening behavior after cycles - Stress/strain Curve

    Noticed lots of people were confused with "mechanical" stress relief (myself was not excluded at the beginning) given that the mechanical cold work would induce working harden leading to a higher strength. In this case, the cyclic loading did the opposite: stress relief. Basically the cycle...
  12. MagBen

    Material Identification

    seems to me Naval brass C464. ASTM B21. Other grades with similar Zn content are C462, C268. not sure what role it is for 0.1% Nb, prossibly to improve mechanical or corrosion resistance. c464 is hard to form a single alpha solid solution alloy, but rather a two-phase alpha+beta. beta...
  13. MagBen

    Equivalent Carbon value influences the tenacity of the material?

    There is no universally accepted equation that directly relates toughness to CE for 4140. However, in general, an increase in CE can lead to a decrease in toughness, while increase in hardness and strength. any specific reason why your HT supplier says the opposite? perhaps they are concerning...
  14. MagBen

    Can someone help me interpret xrf of a magnetic material?

    16th century? this is ancient metallurgy! ancient China, India and Middle East, people used smelting process with iron ore and silica, and added coke as heat source and reducing agent to make Fe-Si alloy. similar to cast iron. Si increase fluidity, decrease melting temp. while mechanically...
  15. MagBen

    High field cryogenic magnetization curves

    @OP: are you looking at M-H curves which will never be "saturated" (flatten)? you need to convert to B-H to subtract the external H effect. From what I saw with austenitic stainless, they are easily to be saturated. magnetic induction tends to increase as temp decreases due to decrease in...
See more

Part and Inventory Search

Back
Top