What is max bar size for 4140 which will full harden with quench severity of 0.35?

1
(No Transcript)
2
What is max bar size for 4140 which will full
harden with quench severity of 0.35?
3
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
4
Quench severity 1.25. What is hardness at
center?
5
Quench severity 1.25. What is hardness at
center?
2" bar quenched at 1.25 corresponds to 7/16" on
Jominy bar
Hardness 53
6
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)
7
Most corrosion is electrochemical
No corrosion if one of these is missing anode
cathode electrolyte
electrical connection
8
Most corrosion is electrochemical
Corrosion at anode Me Men ne (metal
dissolves)
No dissolution at cathode
9
What constitutes an anode/cathode pair?
Dissimilar metals
How do we know? Many combos tried experimentally
10
Result the galvanic series
11
What constitutes an anode/cathode pair?
Dissimilar metals
Different electrolytes
12
What constitutes an anode/cathode pair?
Dissimilar metals
Different electrolytes
13
What constitutes an anode/cathode pair?
Dissimilar metals
Different electrolytes
14
What constitutes an anode/cathode pair?
Dissimilar metals
Different electrolytes
Non-passivated vs. passivated metal or alloy
15
What constitutes an anode/cathode pair?
In summary Anything that makes two half-cells
different gives anode cathode gt corrosion
We can call these types macro cells
16
Then what about micro cells? anode cathode
within single material operating on a micro scale
Grain boundary - high energy regionanodic wrt
bulk of grain
Differently oriented grains - some planes of
atoms dissolve faster than others
Segregation (coring)
17
Then what about micro cells? anode cathode
within single material operating on a micro scale
Segregation (coring)