WELDING

In gas welding, the amount of heat applied to the material being welded is controlled by the

Amount of gas pressure used

Distance the tip is held from the work

Size of the tip opening

Where should the flux be applied when oxyacetylene welding aluminum?

Painted only on the surface to be welded

Painted on the surface to be welded and applied to the welding rod

Applied only to the welding rod

A welding torch backfire may be caused by

A loose tip

Using too much acetylene

A tip temperature that is too cool

If too much acetylene is used in the welding of stainless steel

The metal will absorb carbon and lose its resistance to corrosion

Oxide will be formed on the base metal close to the weld

A porous weld will result

The shielding gases generally used in the Gas Tungsten Arc (GTA) welding of aluminum consists of

A mixture of nitrogen and carbon dioxide

Helium or argon, or a mixture of helium and argon

Nitrogen or hydrogen, or a mixture of nitrogen and hydrogen

Cylinders used to prevent to transport and store acetylene

Contain acetone

Are pressure tested to 3,000 PSI

Are green in color

Which of the following can normally be welded without adversely affecting strength?

1. Aircraft bolts

2. SAE 4130 chrome/molybdenum tubing

3. Spring steel struts

4. Most heat-treated steel/nickel alloy components

1 and 3

2 and 4

Oxides form very rapidly when alloys or metals are hot. It is important, therefore, when welding aluminum to use a

Solvent

Flux

Filler

When a butt welded joint is visually inspected for penetration

Look for evidence of excessive heat in the form of a very high bead

The penetration should be 100 percent of the thickness of the base metal

The penetration should be 25 to 50 percent of the thickness of the base metal

In Gas Tungsten Arc (GTA) welding, a stream of inert gas is used to

Concentrate the heat of the arc and prevent its dissipation

Prevent the formation of oxides in the puddle

Lower the temperature required to properly fuse the metal

The oxyacetylene flame used for aluminum welding should

Be slightly oxidizing

Be neutral and soft

Contain an excess of acetylene and leave the tip at a relatively low speed

High pressure cylinders used to transport and store acetylene must

Be pressure tested to 3,000 PSI

Contain acetone

Be green in color

How should a welding torch flame be adjusted to weld stainless steel?

Neutral

Slightly carburizing

Slightly oxidizing

Which statement concerning soldering is correct?

Joints in electric wire to be soldered should be mechanically secure prior to soldering

If the soldering temperature is too high, the solder will form in lumps and not produce a positive bond

Changeable shades of blue can be observed on the surface of a copper soldering tip when the proper temperature for soldering has been reached

The most important consideration (s) when selecting welding rod is

Material compatibility

Ambient conditions

Current setting or flame temperature

In selecting a torch tip size to use in welding, the size of the tip opening determines the

Amount of heat applied the work

Melting point of the filler metal

Temperature of the flame

Engine mount members should preferably be repaired by using a

Smaller diameter tube with fish mouth and rosette welds

Larger diameter tube with fish mouth and rosette welds

Larger diameter tube with fish mouth and no rosette welds

A very thin and pointed tip on a soldering copper is undesirable because it will

Have tendency to overheat and become brittle

Cool too rapidly

Transfer too much heat to the work

What method of repair is recommended for a steel tube longeron dented at a cluster

Welded split sleeve

Welded outer sleeve

Welded patch plate

Acetylene at a line pressure above 15 PSI is

Dangerously unstable

Usually necessary when welding metal over 3/8-inch thick

Used when a reducing flame is necessary

Which statement concerning a welding process is true?

In the oxyacetylene welding process, the filler rod used for steel is covered with a thin coating of flux

In the metallic-arc welding process, filler material, if needed, is provided by a separate metal tool of the proper material held in the arc

The inert-arc welding process uses an inert gas to protect the weld zone from the atmosphere

Welding over brazed or soldered joint is

Not permitted

Permissible for mild steel

Permissible for most metals or alloys that are not heat treated

Why should a carburizing flame be avoided when welding steel?

A cold weld will result

It removes the carbon content

It hardens the surface

Which statement best describes magnesium welding?

Filler rod should be nickel-steel

Magnesium can be welded to other metals

Filler rod should be the same composition as a base metal

Why is it necessary to use flux in all silver soldering operations?

To prevent overheating of the base metal

To chemically clean the base metal of oxide film

To increase heat conductivity

Edge notching is generally recommended in butt welding above a certain thickness of aluminum because it

Aids in getting full penetration of the metal and prevents local distortion

Aids in the removal or penetration of oxides o the metal surface

Helps hold the metal in alignment during welding b.

Filing or grinding a weld bead is considered to be

An acceptable means t7o achieve a smoother surface

A way to bring about strength reduction in joint

Frequently necessary to avoid adding excess weight to a weld joint

What purpose does flux serve in welding aluminum?

Minimizes or prevents oxidation

Ensures proper distribution

Removes dirt, grease, and oil

A resurfaced soldering iron cannot be used effectively until after the working face has been

Polished

Tinned

Fluxed

Which statement is true in regard to welding heat-treated magnesium?

The welded section does not have the strength of the original metal

Magnesium cannot be repaired by fusion welding because of the high probability of igniting the metal

Flux should not be used because it is very difficult to remove and is likely to cause corrosion

Annealing of aluminum

Makes the material brittle

Increases the tensile strength

Removes stresses caused by forming

Why are aluminum plates ¼ inch or more thick usually preheated before welding?

Reduces internal stresses and assures more complete penetration

Reduces welding time

Prevents corrosion and ensures proper distribution of flux

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