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Understanding Jominy Test, Quenching, and Corrosion in Steel

Learn about the Jominy test for hardness measurement, quenching methods, and the electrochemical process of corrosion in steel. Explore practical examples and design problems. Access helpful information from Timken Handbook.

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Understanding Jominy Test, Quenching, and Corrosion in Steel

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  1. The universe is a playground of improvisation – it follows no external pattern –Cogitor Reticulus

  2. From Timken handbook (http://www.timken.com/timken_ols/steel/handbook/PracticalDataHandbook.zip) NICKEL - Ni is used in low alloy steels to reduce the sensitivity of the steel to variations in heat treatment and distortion and cracking on quenching. It also improves low temperature toughness and hardenability.

  3. Jominy test Specimen & water quench Hardness measurement

  4. Jominy test

  5. Quench severities

  6. 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?

  7. 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

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

  9. 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

  10. 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)

  11. 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

  12. 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

  13. 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

  14. Assignment: Review today's classnotes a. Jominy test b. Jominy curves c. quench severities d. Galvanic cell

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