Oxy-Acetylene Welding and Cutting | Page 2

repetition and all theoretical, historical and similar
matter that is not absolutely necessary.
Free use has been made of the information given by those
manufacturers who are recognized as the leaders in their respective
fields, thus insuring that the work is thoroughly practical and that it
represents present day methods and practice.
THE AUTHOR.

CONTENTS

CHAPTER I
METALS AND ALLOYS--HEAT TREATMENT:--The Use and
Characteristics of the Industrial Alloys and Metal Elements--Annealing,
Hardening, Tempering and Case Hardening of Steel
CHAPTER II
WELDING MATERIALS:--Production, Handling and Use of the
Gases, Oxygen and Acetylene--Welding Rods--Fluxes--Supplies and
Fixtures
CHAPTER III
ACETYLENE GENERATORS:--Generator Requirements and
Types--Construction--Care and Operation of Generators.
CHAPTER IV
WELDING INSTRUMENTS:--Tank and Regulating Valves and
Gauges--High, Low and Medium Pressure Torches--Cutting
Torches--Acetylene-Air Torches
CHAPTER V
OXY-ACETYLENE WELDING PRACTICE:--Preparation of
Work--Torch Practice-- Control of the Flame--Welding Various Metals
and Alloys--Tables of Information Required in Welding Operations
CHAPTER VI
ELECTRIC WELDING:--Resistance Method--Butt, Spot and Lap
Welding--Troubles and Remedies--Electric Arc Welding
CHAPTER VII
HAND FORGING AND WELDING:--Blacksmithing, Forging and
Bending--Forge Welding Methods

CHAPTER VIII
SOLDERING, BRAZING AND THERMIT WELDING:--Soldering
Materials and Practice-- Brazing--Thermit Welding
CHAPTER IX
OXYGEN PROCESS FOR REMOVAL OF CARBON
INDEX

OXY-ACETYLENE WELDING AND CUTTING, ELECTRIC AND
THERMIT WELDING

CHAPTER I
METALS AND THEIR ALLOYS--HEAT TREATMENT
THE METALS
_Iron._--Iron, in its pure state, is a soft, white, easily worked metal. It is
the most important of all the metallic elements, and is, next to
aluminum, the commonest metal found in the earth.
Mechanically speaking, we have three kinds of iron: wrought iron, cast
iron and steel. Wrought iron is very nearly pure iron; cast iron contains
carbon and silicon, also chemical impurities; and steel contains a
definite proportion of carbon, but in smaller quantities than cast iron.
Pure iron is never obtained commercially, the metal always being
mixed with various proportions of carbon, silicon, sulphur, phosphorus,
and other elements, making it more or less suitable for different
purposes. Iron is magnetic to the extent that it is attracted by magnets,
but it does not retain magnetism itself, as does steel. Iron forms, with
other elements, many important combinations, such as its alloys, oxides,
and sulphates.

[Illustration: Figure 1.--Section Through a Blast Furnace]
_Cast Iron._--Metallic iron is separated from iron ore in the blast
furnace (Figure 1), and when allowed to run into moulds is called cast
iron. This form is used for engine cylinders and pistons, for brackets,
covers, housings and at any point where its brittleness is not
objectionable. Good cast iron breaks with a gray fracture, is free from
blowholes or roughness, and is easily machined, drilled, etc. Cast iron
is slightly lighter than steel, melts at about 2,400 degrees in practice, is
about one-eighth as good an electrical conductor as copper and has a
tensile strength of 13,000 to 30,000 pounds per square inch. Its
compressive strength, or resistance to crushing, is very great. It has
excellent wearing qualities and is not easily warped and deformed by
heat. Chilled iron is cast into a metal mould so that the outside is
cooled quickly, making the surface very hard and difficult to cut and
giving great resistance to wear. It is used for making cheap gear wheels
and parts that must withstand surface friction.
_Malleable Cast Iron._--This is often called simply malleable iron. It is
a form of cast iron obtained by removing much of the carbon from cast
iron, making it softer and less brittle. It has a tensile strength of 25,000
to 45,000 pounds per square inch, is easily machined, will stand a small
amount of bending at a low red heat and is used chiefly in making
brackets, fittings and supports where low cost is of considerable
importance. It is often used in cheap constructions in place of steel
forgings. The greatest strength of a malleable casting, like a steel
forging, is in the surface, therefore but little machining should be done.
_Wrought Iron._--This grade is made by treating the cast iron to
remove almost all of the carbon, silicon, phosphorus, sulphur,
manganese and other impurities. This process leaves a small amount of
the slag from the ore mixed with the wrought iron.
Wrought iron is used for making bars to be machined into various parts.
If drawn through the rolls at the mill once, while being made, it is
called "muck bar;" if rolled twice, it is called "merchant bar" (the
commonest kind), and a still better grade is made by rolling a third time.
Wrought iron is being gradually replaced in use by mild rolled steels.

Wrought iron is slightly heavier than cast iron, is a much better
electrical conductor than either cast iron or steel, has a tensile strength
of 40,000 to 60,000 pounds per square inch and costs slightly more
than steel. Unlike either steel or cast iron, wrought iron does not harden
when cooled