Chapter 36

Question 1

Oxyfu gas welding

Answer 1

Welding processes that use the flame produced by combustion as a source of heat. Torch is used for this process

Question 2

The torch has how many reactions

Answer 2

2

Question 3

First reaction?

Answer 3

Oxygen and acetylene react to produce carbon monoxide and hydrogen. Occurs near the tip of the torch and generates intense heat

Question 4

Second stage?

Answer 4

Combustion of CO and H2 and occurs just beyond the first combustion zone. Second stage produces a flame having two distinct regions, a light blue inner cone and a darker blue outer cone.

Question 5

Putter flame?

Answer 5

Outer envelope of the flame preheats the metal and shields it from oxidation

Question 6

Neutral flame.

Answer 6

More oxygen to acetylene. Most welding is done with a neutral flame, less chemical effect

Question 7

Oxidizing flame

Answer 7

A higher ratio of oxygen produces an oxidizing flame, usually has a crackling sound. Flame temperature is not that great.

Question 8

Mapp

Answer 8

Methyl acetylene propadiene (mapp) is an alternative for acetylene. Second hottest gas’s.

Question 9

Propylene

Answer 9

Alternative gas, consists of propane and ethylene

Question 10

Larger tip of flame

Answer 10

Greater heat input

Question 11

Oxyfuel welding is primarily

Answer 11

Fusion welding

Question 12

Filler metal

Answer 12

Can be added In The form of solid metal or rods.

Question 13

Fluxes

Answer 13

Can be used to clean surfaces and remove contaminating oxide. Gaseous shield from flux can prevent further oxidation.

Question 14

Issues with welds?

Answer 14

Heat source is not concentrated and can lead to distortion

Question 15

Oxyflame pros?

Answer 15

Low carbon steel is typically welded. Portable and I expensive, extremely versatile.

Question 16

Pressure gas welding

Answer 16

Uses a gas flame and then forces together the materials. This is a form of solid state welding. Coalescences is produced by pressure.

Question 17

Arc

Answer 17

A concentrated heat source that can produce temperatures that’s re very high.

Question 18

Electrodes

Answer 18

Carbon rod is one electrode, the work piece is the other.

Question 19

Direct current electrode negative or straight polarity

Answer 19

The electrode is made negative and direct current is used. Fast melting of electrode and a shallow molten pool

Question 20

Direct current electrode positive or reverse polarity

Answer 20

The work is made negative and the electrode positive. Metal deposition is lower, but deeper penetration happens.

Question 21

Alternating currents and variable polarity

Answer 21

Alternates between dcen and dcep.

Question 22

Consumable electrode processes

Answer 22

In one group of arc welding processes the electrode is consumed. No metal is needed to fill.

Question 23

No consumable electrode processes

Answer 23

A tungsten or carbon electrode is used, but not consumed, except by slow vaporization. A delegate metal wire is required to supply filler metal.

Question 24

Types of consumable arc welding

Answer 24

Shielded metal arc welding and gas metal arc welding

Question 25

Shielded metal arc welding or stick welding

Answer 25

Versatile and low cost.

Question 26

Shielded metal arc welding contains a wire with a coating that does:

Answer 26

Vaporize to protect the atmosphere. Provides ionized elements to stabilize the arc. Act as a flux to deodorize and remove impurities. Provide a protective slag to accumulate purities. Add alloying elements for strength. Add additional fillers. Affect arc penetration. Influence shape of weld bead.

Question 27

How to shielded metal:

Answer 27

Operator touches the electrode to the workpiece and raises it to a stable state

Question 28

Best used for what materials: shielded metal welding

Answer 28

Ferrous metals: carbon steels, alloy steels, stainless steels, and cast irons.

Question 29

Gas metal arc welding

Answer 29

The electrode becomes uncoated, no flux is needed. Shielding is provided by the gas, no Slags or fluxes needed. Can be used for all metals.

Question 30

Shielding gases for gas arc welding?

Answer 30

Have an effect on stability. Helium produces hottest arc and deepest penetration. CO2 is the opposite. Argon is heavier and requires lower flow rates. Helium is light and requires higher flow rates.

Question 31

Pros of gas welding?

Answer 31

Fast and economical. Accounts for more than half of all weld metal deposition.

Question 32

Advanced gas welding

Answer 32

Uses a second power source to preheat the filler metal

Question 33

Gas tungsten arc welding knoe as he liard welding. Nonconsumable.

Answer 33

A nonconsumable electrode provides the arc but not the filler metal. Inert gas flows through the electrode holder to provide a shield.

Question 34

Gas tungsten welding pros?

Answer 34

Most versatile of arc welding processes. No cleaning or slag must be removed. Many common metals and alloys can be welded.

Question 35

Gas tungsten cons

Answer 35

Costs more and is slower, but produces a high quality weld.