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  1. AndrewFinAustralia

    Relative contribution of interstitial carbon vs pearlite to strength of plain carbon steels

    Found an answer in part in an article on pearlitic wire. Mainly Hall-Petch strengthening between the pearlite lamellae. Fracture and shear of the cementite occurs, but it's not the primary contribution to strength. - it does initiate microvoids which can reduce ductility. I was going to link...
  2. AndrewFinAustralia

    304 Stainless Steel Sink Discoloration

    The mark will probably polish out. If it doesn't and it's deep, then cause for concern, but I'm guessing it wasn't installed looking like this. Modern steelmaking processes aren't that dirty that you'd have an inclusion or material fault of this scale.
  3. AndrewFinAustralia

    Concrete under tension - relation between crack opening and cracking strain?

    Hard to tell. You'd need to see the full article. I read the 0.9 f<sub>ctm</sub> as being 10% factor of safety in the loading. I have no idea what the 'ctm' stands for in this instance. It just indicates to me that a strain from 0.11 to 0.15 occurred with no major increase in stress (ie...
  4. AndrewFinAustralia

    Relative contribution of interstitial carbon vs pearlite to strength of plain carbon steels

    Thanks Dhurjati, I actually had a copy of Dieter here as well - looked it up as per your suggestion, but it covered the Hall-Petch equation and general strengthening explanation for grain size modification. Have you any idea of research that quantifies the strengthening mechanism in a plain...
  5. AndrewFinAustralia

    Relative contribution of interstitial carbon vs pearlite to strength of plain carbon steels

    Hi All, Am an honours-qualified Materials Engineer with 15 years experience, prior to teaching high school students since 2002. The content of the course I teach is at the first-year university level, excluding calculus, delivered over 2 years. With COVID-19, I'm teaching my senior class via...
  6. AndrewFinAustralia

    Urgent question, Residual stress

    ...applications, carbides in the steel are a no-no as Chromium tends to be a trifle cytotoxic when the carbides dissolve. A stress relieve anneal would fix this, but I'm not sufficiently knowledgeable of the behaviour of this grade of stainless to comment on the interactions occurring at 450*C
  7. AndrewFinAustralia

    2,000 Degrees Fahrenheit

    Boltslinger, There are a lot as outlined above. Key point that hasn't been explored is the environment and the stress loading. Is there a cyclic stress as well? You probably should be looking at creep resistance also. Is the environment oxidising, reducing, acidic...
  8. AndrewFinAustralia

    "Mission Critical" Jobs for Materials Engineers?

    Confused, I interned for 7 years as I did a degree part time. At the end of the day, when you enjoy your work it ceases to become work and then you learn easily and are successful. Engineering depends upon continuous learning as you know. Ed's advice on being able to present and listening...
  9. AndrewFinAustralia

    SAE 1144 shaft fracture surface morphology

    Just a quick dot point not mentioned above. This fracture pattern is intergranular fracture above along the prior austenite grain boundaries (which is where the sulphide stringers form) You will also see this pattern in weld sensitised areas of rolled steel. Cheers,
  10. AndrewFinAustralia

    After what temperatures and times will scale form on grades 1035 and 1050?

    Hi again, That paper for download I gave you last time has this info. Was it 550C for reasonable scale formation? As with all metallurgical processes, it's time and temp that relate to reaction - typical arrhenius reactions. Cheers,
  11. AndrewFinAustralia

    316SS Forging process work flow

    Careful, Just to add (and I'm aware that I'm probably telling you something you know already) the scale is ceramic and abrasive - it can pick up small particles of material from the die. AF
  12. AndrewFinAustralia

    316SS Forging process work flow

    Hi Careful, There's a lot here that work with/specify stainless daily - I'll defer to them. To answer the question "Why does the scale rust" - Scale is, by definition, the oxide layer. Either this oxidised stainless has picked up chloride/sulfur compounds during fabrication, and you're seeing...
  13. AndrewFinAustralia

    Heat Growth on 52100 Material

    Tolerance of 1.4 microns - 2 microns. This is getting towards F1 tolerances - the mills that grind these are in a climate controlled room with coolant at a specific temperature. If you know the heat profile in the ball, you could use standard coefficient of expansion, but to be honest, for...
  14. AndrewFinAustralia

    design temperature limits for various metals

    Depends upon the property you're looking at designing against ornerynorsk. The advice above is spot-on. eg: if it's a beam in a walking beam furnace, max service temp = 300C. If it was scale resistance, it'd be higher and dependent upon composition.
  15. AndrewFinAustralia

    Very Curious Weld Defect

    No problem - Hope you get to the bottom of it if needed. We used to leave a chimney in a cement kiln open to give a working draft to those in the kiln during repair - similar sized chimney @ 60m The only way we could work at the back end of the kiln was to shut the dampers completely to avoid...
  16. AndrewFinAustralia

    Heat Pattern Scale formation on grades 1035A4 and 1035S1

    Just noticed you said you were an intern. I did a quick google search for some papers to help guide you - I was a trainee metallurgist (similar to your internship) in our local steel company - degree was 7 years part time while I worked in the trade from the age of 18. Here's two immediate...
  17. AndrewFinAustralia

    Heat Pattern Scale formation on grades 1035A4 and 1035S1

    Former cold mill and pickle line technical assistant (process metallurgist) in a 1000tpd plant in the late 80's/early 90's when I finished my degree so knowledge is a bit dated. Easiest option is the trial as mentioned above, but you need to find a way to measure it. While time at temperature...
  18. AndrewFinAustralia

    Very Curious Weld Defect

    Massive draft - I think from memory 10"WG at the bottom of a 60m vertical chimney, which would be the same as your case with a 60m height. I haven't got my chemical engineer's handbook handy at the moment. Was the defect along the whole weld? AF
  19. AndrewFinAustralia

    Very Curious Weld Defect

    Horizontal, not flat - thanks It's almost as though there's some sort of pressure buildup on the other side of the weld that's blowing the metal out of the weld pool was the only thing I could think of for the consistent size of the 'extrusions' - I've got a basic welding ticket and used to...
  20. AndrewFinAustralia

    Corner pitting after pressure test

    Hi Lyrl, I read original post as items not being in service and the spalling post pressure test immediately. Whilst I haven't read the link on case crushing above, in the past, I had issues in the past with a maximum stress concentration during pressure application being at the depth where...

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