1 / 15

Last class - Ceramic tools Cast irons

Last class - Ceramic tools Cast irons. Today - Case hardening Hardenability test Quenching design. Case hardening. Gear tooth. Carburizing - pack & gas - add C from CO gas. Nitriding - add N from NH 3. Case must be Q & T, except for nitrided. Carbonitriding - add C & N from CO & NH 3.

sgroom
Download Presentation

Last class - Ceramic tools Cast irons

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Last class - Ceramic tools Cast irons Today - Case hardening Hardenability test Quenching design

  2. Case hardening Gear tooth Carburizing - pack & gas - add C from CO gas Nitriding - add N from NH3 Case must be Q & T, except for nitrided Carbonitriding - add C & N from CO & NH3

  3. Case hardening Alternate case hardening method Induction hardening - surface heating by high-frequency AC, then Q & T

  4. Truck rear axle shaft Ford uses SAE 1050 steel with manganese content modified from 0.80 to 1.10% in rear axle shafts. Normally 0.60-0.90 Mn YS = 49 ksi, TS = 90 ksi, EL = 15% (hot-rolled) YS = 80 ksi, TS = 120 ksi (Q+T) depends on heat treat conditions

  5. Jominy test Specimen & water quench Hardness measurement

  6. Jominy test

  7. Quench severities

  8. Example quench design problems Jominy curve 6 6 What is max bar size for 4140 which will full harden with quench severity of 0.35?

  9. Example quench design problems 6 What quench should be used for 2" diam. 4140 bar to full harden 1/2" deep? Quench severity ≈ 1.25 Water quench w/some agitation

  10. Example quench design problems 7 Quench severity ≈ 1.25. What is hardness at center?

  11. Example quench design problems Jominy curve 7 Quench severity ≈ 1.25. What is hardness at center? 2" bar quenched at 1.25 corresponds to 7/16" on Jominy bar Hardness ≈ 54

  12. Corrosion Hint for exams (and life): A substance which is corrosive will corrode other substances SS is thus certainly non-corrosive But it is also non-corrodable (in most instances)

  13. Corrosion Galvanic cell is necessary electrical connection anode cathode electrolyte Most corrosion is electrochemical No corrosion if one of these is missing: anode cathode electrolyte electrical connection

  14. Corrosion Galvanic cell is necessary electrical connection anode cathode electrolyte Most corrosion is electrochemical Corrosion at anode Me = Me+n + ne– (metal dissolves) No dissolution at cathode

  15. Corrosion electrical connection Zn Cu electrolyte What constitutes an anode/cathode pair? Dissimilar metals Ex: Cu & Zn (Zn corrodes) How do we know? Many combos tried experimentally

More Related