419 Flashcards
Smaw is started by touching the end of an electrode to the base metal and then lifting the electrode about ___ in to make an arc. The arc produces temperatures in the range of __ degrees
1/4, 10,000
In shielding metal arc welding the shield is made of
gas
In smaw it is important to understand the lengthening the arc __ the resistance, which ___ the temperature.
Increases, Increases
smaw electrodes are classified by their
core material
which of the following items offers protection from arc flash
welding helmet
important factors to consider when selecting smaw electrodes include the
composition of the base metals
welding electrodes are identified by the letter ___ followed by a number. The first two digits of the number identify the __
E, tensile strength of the deposited metal
when selecting an electrode for smaw you should consider the current range which depends mainly on the
diameter of the electrode
what kind of covered electrode allows you to use high welding current without causing excessive penetration
iron powder
electrodes covered with ___ must not be allowed to become to dry
cellulose
in which of the following is electrode metal deposited when direct contact occurs between the electrode and the base metal
short circuit
which of the following is a common gmaw shielding gas
argon
the best shielding gas for a flat or horizontal gmaw weld is one that is
heavier than air
generally, the main consideration when selecting an electrode wire for a gmaw application is the
base metal composition
when preparing to operate a gmaw gun position its nozzle about ___ in above the work and tilt it about ___ degrees off vertical in the direction of the welding
3/4, 20
gtaw equipment and supplies may include which of the following
air cooled torch
the purpose of the gtaw electrode is to
conduct electricity
when using gtaw to weld a very thick piece of low carbon steel you should use ___ as shielding gas and __ as the filler metal
helium, low carbon steel
when welding stainless steels with gtaw you should use ___ current and when welding aluminum you should use ___ current
DCEN , ACHF
which of the following is an advantage of gtaw over other welding processes
can weld a large variety of metal
resistance welding uses electric current and __ to join metals
pressure
submerged arc welding is unique in that the electricity passes through a layer of
flux
plasma arc welding is unique in that the electricity passes through a layer of
ionized gas
which of the following is part of conventional fiction welding
spinning part
one advantage of ultrasonic welding over other types of welding is that it
can make leak-tight joints in thin materials
preheating parts before welding them reduces the
distortion of the welded structure
uneven or rapid heating during welding causes __ in a material which can in turn cause ___
expansion, deformation
the heat affected zone of a metal can undergo permanent changes in its
mechanical properties
what should be your primary consideration when deciding whether or not preheating of a ferrous metal is necessary
carbon content
which of the following conditions indicates a possible need for postheating
rapid cooling after preheating
ferrous metals are those metals that are __ based
iron
which of the following is a step in edge preparation for ferrous metals
cutting or gouging the edge
the most common method used for welding cast iron is
smaw
cast iron can be welded at low currents in any position with ___ smaw electrodes
nickel based
when welding alloy steels you should use __- electrodes and ___ current
low hydrogen, DCEP
an important property of aluminum that you should be aware of is that it
readily forms an oxide coating
which is the best way to determine the kind of metal a part is made of
contact the part manufacturer
the most widely used are process for cutting nonferrous metals is
air carbon
using a chemical cleaner to clean aluminum before welding slows the rate at which the
oxidation reforms
When welding nickel use the ___ process and a ___ power supply
GTAW, DCEN
compared to other kinds of pipe joints welded pipe joints are
stronger
welding pipe in high pressure systems requires that a welder have which AWS qualification level
AR-1
which of the following is the most widely used pipe welding process
smaw
weld backup rings are special accessories that help prevent __ in pipe welding
icicles
the need for preheating and postheating when welding pipe depends on
base metal composition and pipe thickness
wear caused by grinding or scratching action of hard particles is called
abrasion
cross-checking is desirable in some surfacing deposits because it
relieves residual stress
the hardest and most wear resistant hard facing metals are
tungsten carbide
the technique of ___ is especially useful for building up thin edged tools
Oxyacetylene hard facing
most automatic hard facing is done with __ machines
saw
