Informational Site NetworkInformational Site Network
Privacy
 
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

Molybdenum
Molybdenum steels have been made commercially for twenty-five...

Phosphorus
Phosphorus is one of the impurities in steel, and it has been...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

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

Chromium
Chromium when alloyed with steel, has the characteristic func...

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Quenching
It is considered good practice to quench alloy steels from th...

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

Conclusions
Martien was probably never a serious contender for the honor ...

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

Alloying Elements
Commercial steels of even the simplest types are therefore p...

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...



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



Add to del.icio.us Add to Reddit Add to Digg Add to Del.icio.us Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network
Report
Privacy
SHAREADD TO EBOOK


Viewed 3364