Unit 6: Material Science & Welding Technology

Question 1

Hardness

Answer 1

is the ability to resist wear, abrasion, cutting, and indentation.

Question 2

Brittleness

Answer 2

Brittle materials break under pressure with little bending or warning. Brittle materials can be quite strong such as white cast iron but only up until their breaking point. Brittleness refers only to a material’s failure mode

Question 3

Ductility

Answer 3

Is the ability of a material to be permanently deformed under a tensile load without breaking. Ductile materials can be extended or drawn out with little propensity to break.

Question 4

Elasticity

Answer 4

Refers to the ability of a material to return to its original shape after deforming forces have been removed.

Question 5

Plasticity

Answer 5

Are materials that are soft and easily deformed. They have very little elasticity and are considered the opposite of brittleness.

Question 6

Malleability

Answer 6

Is the ability of a material to be permanently deformed under compressive loads, without breaking. Is generally increased in a material through applying heat. Allows a material to be hammered or rolled into other sizes and shapes.

Question 7

Strength

Answer 7

The property that allows a material to resist deformation under load.

Question 8

Toughness

Answer 8

Determines how large of a single impact or hit a material can take before failure.

Question 9

Ferrous Materials vs Non-Ferrous Materials

Answer 9

The simple answer is that ferrous metals contain iron and non-ferrous metals do not. The more in-depth answer is that ferrous metals and non-ferrous metals each have their own distinctive properties. These properties determine the applications they are most suited for.

Non-ferrous metals have been used since the beginning of civilization. The discovery of copper in 5,000 BC marked the end of the Stone Age and the beginning of the Copper Age. The later invention of bronze, an alloy of copper and tin, started the Bronze Age.

The use of ferrous metals started in around 1,200 BC when iron production started to become commonplace. This ushered in the Iron Age.

Question 10

Non-Fusion Welding

Answer 10

Soldering and Brazing
Use filler metal that is different from parent metal
Weaker then Fusion welding

Question 11

OFW

Answer 11

Oxy-Fuel Welding
is a fully manual process that uses oxygen and fuel mixed
One hand has to hold filler metal

Question 12

Tack Welds

Answer 12

Small welds to hold work pieces in position while the material is being welded

Question 13

Single-Welded vs Double Welded

Answer 13

Single welds are done on one side of material, while double does it on both sides. Double is done for thicker materials

Question 14

Fillet Welds

Answer 14

Have backing material or parent material behind them

Question 15

Groove Welds

Answer 15

Welds that have no parent material behind them

Question 16

Root Pass

Answer 16

First pass when welding

Question 17

Weld Indication

Answer 17

An observed condition that maybe point to a weld defect

Question 18

Common Weld Defects

Answer 18

Porosity: trapped gas in welds
Inclusions: trapped slag or tungsten in the weld
Cracks:
Undercut: unfilled section on the weld
Incomplete penetration: filler material does no extend through entire thickness of parent material

Question 19

SMAW

Answer 19

Shielded Metal Arc Welding

The most commonly used welding process
Uses electricity and an electrode
Electrode makes contact with workpiece and conducts electricity melting the electrode and work together by fusion

Question 20

Temperature produced by SMAW

Answer 20

Between 3000-8300 C

Question 21

Advantages/Disadvantages of SMAW?

Answer 21

Its low cost and ease of use
Its open arc creates large amounts of heat radiation (ultraviolet light and infrared) that requires more protection from (Eyes especially)

Question 22

SAW

Answer 22

Submerged Arc Welding
Generally used on steel structures and Pressure vessels
Limited to mainly ferrous materials
As the name suggests the arc weld is submerged by the flux that protects the weld from the atmosphere
The flux prevents oxidation from occurring and reduces weld defects immensely
The process can is semi or fully automatic but still requires lots of operator skill to know which flux to use with the electrode and base metal
Has a high deposition rate or fast weld rate
Between 3000-8300 C
Its low cost and ease of use
Its open arc creates large amounts of heat radiation (ultraviolet light and infrared) that requires more protection from (Eyes especially)

Question 23

GTAW

Answer 23

Gas Tungsten Arc Welding
Best suited for difficult-to-weld non-ferrous materials or welding two dissimilar materials
Is a clean process that is not too expensive
Although requires high operator skill and the weld site must be very clean

Question 24

GMAW

Answer 24

Gas Metal Arc Welding
Works through electricity melting the workpiece and electrode together
The gas supplied over the weld prevents oxidation and weld defects
Generally, carbon dioxide is used as the inert gas
Can be used on both ferrous and non-ferrous metal
Provides high quality welds with high deposition rates

Question 25

Butt Welding

Answer 25

Used on pipe larger then 51mm Requires preparation of the weld site in order to create the strongest bond between the parent metal and weld material
Generally, a bevel is created by grinding down the weld site to a specific angle and root opening

Question 26

Weld Preheating

Answer 26

Used to avoid the heat stress that occurs when welding a room temperature parent material. The preheat temperature is different for each parent material

Question 27

Postweld Heating Treatment (Stress Relieving)

Answer 27

Used to avoid the thermal stress that occurs if a weld cools down too quickly. Welds cooling too quickly can cause hot cracking