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Steel Making

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Annealing
There is no mystery or secret about the proper annealing of d...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

The Influence Of Size
The size of the piece influences the physical properties obta...



The Effect Of Tempering On Water-quenched Gages






Category: HARDENING CARBON STEEL FOR TOOLS

The following information has been supplied by Automatic and Electric
Furnaces, Ltd., 6, Queenstreet, London, S. W.:

Two gages of 3/4 in. diameter, 12 threads per inch, were heated
in a Wild-Barfield furnace, using the pyroscopic detector, and
were quenched in cold water. They were subsequently tempered in a
salt bath at various increasing temperatures, the effective diameter
of each thread and the scleroscope hardness being measured at each
stage. The figures are in 10,000ths of an inch, and indicate the
change + or - with reference to the original effective diameter
of the gages. The results for the two gages have been averaged.

TABLE 24.--CHANGES DUE TO QUENCHING
----------------------------------------------------------------
After Tempering temperature, degrees Centigrade
Thread quenching-----------------------------------------
220 260 300 340 380 420
---------------------------------------------------------
1 +25 +19 +17 +15 +13 +11 +11
2 +18 +12 +11 + 9 + 6 + 5 + 5
3 +12 + 6 + 5 + 3 0 0 0
4 +10 + 4 + 4 + 2 ... 0 - 1
5 + 9 + 4 + 4 + 2 0 0 0
6 + 9 + 4 + 3 + 2 0 0 0
7 +10 + 5 + 5 + 3 + 2 + 1 + 2
8 + 8 + 4 + 3 + 2 0 0 + 1
9 + 9 + 4 + 3 + 2 + 1 + 1 + 1
10 + 9 + 5 + 5 + 3 + 2 + 2 + 2
11 + 7 + 4 + 4 + 2 + 1 + 1 + 1
12 + 9 + 5 + 5 + 5 + 4 + 4 + 3

Scleroscope 80 70 70 62 56 53 52
----------------------------------------------------------------

Had these gages been formed with a plain cylindrical end projecting
in front of the screw, the first two threads would have been prevented
from increasing more than the rest. The gages would then have been
fairly easily corrected by lapping after tempering at 220 deg.C. Practically
no lapping would be required if they were tempered at 340 deg.C. There
seems to be no advantage in going to a higher temperature than
this. The same degree of hardness could have been obtained with
considerably less distortion by quenching directly in fused salt. It
is interesting to note that when the swelling after water quenching
does not exceed 0.0012 in., practically the whole of it may be
recovered by tempering at a sufficiently high temperature, but when
the swelling exceeds this amount the steel assumes a permanently
strained condition, and at the most only 0.0014 in. can be recovered
by tempering.





Next: Tempering Colors On Carbon Steels

Previous: Tempering Round Dies



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