Steelmaking.ca Home Steel Making Categories Manufacturing and the Economy of Machinery

Steel Making

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

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

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

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

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Connecting Rods
The material used for all connecting rods on the Liberty engi...

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

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

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...



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 Informational Site Network
Report
Privacy
ADD TO EBOOK


Viewed 4606