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85 Cards in this Set
- Front
- Back
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What is hardness? |
The ability to resist wear, abrasion, cutting and indentation |
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What is the Brinell Tester? |
A ball in a hydraulic press is pressed into the specimen and the dent diameter is measured |
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Wha is the Rockwell Tester? |
A 1.6mm ball or cone is pressed with 100kg. The impression is converted to hardness reading |
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What is brittleness? |
No deformation before breaking, breaks instantly |
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What is ductility? |
Can be permanently deformed without breaking |
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What is plasticity? |
Very soft and a tiny amount of elasticity. Plasticity is the opposite of brittleness |
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What is elasticity? |
Ability to return to its original shape after force is removed |
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What is malleability? |
Can be hammered or rolled into other shapes. Malleability is increased when heated |
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What is toughness? |
Materials that do not break easily under sudden impacts |
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What is the Izod test? |
One end is held in a vice and it is struck on the side. the energy required to break is the test. |
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What is the Charpy test? |
The same as the Izod, however both side are supported and it is struck in the middle. |
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What is pig iron? |
The first stage of iron produced from iron ore |
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How is pig iron made? |
Iron ore is heated with coke and limestone, the slag on top is removed, and the remaining molten is pig iron |
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What is pig iron used for? |
It is refined to make steel or cast iron. |
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How is cast iron made? |
It is melted pig iron mixed with scrap iron. |
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What is the carbon content of cast iron? |
2 - 4% |
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What is white cast iron and what is it used for? |
White cast iron is very hard and brittle. It is mainly used for thing that will be subjected to excessive wear |
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What is grey cast iron and what is it used for? |
It is a more softer iron than white cast iron, and has a good compressive strength. It is mainly used for machine bases and supports |
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What is malleable cast iron? |
It is white cast iron that has been annealed to make it more tough and durable |
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What is annealing? |
The process of heating and cooling a metal at a controlled rate. |
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If the carbon content in iron is less than 2%, what is it? |
Steel |
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If the carbon content in iron is more than 2%, what is it? |
Cast iron |
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What are the 2 groups of steels? |
1. Plain carbon steel 2. Alloy Steel |
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How are carbon steels grouped? |
Low - 0.005% - 0.3% carbon Med - 0.3% - 0.45% carbon High - 0.45% - 0.75% carbon Very high - 0.75% - 1.5% carbon |
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What are the 8 alloys added to steel? |
1. Nickel 2. Chromium 3. Molybdenum 4. Vanadium 5. Copper 6. Lead 7. Manganese 8. Tungsten |
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What are the advantages of adding nickel to steel? |
- Excellent resistance to corrosion - Improves toughness - Good for bearings |
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What are the advantages of adding Chromium to steel? |
- Resistance to oxidization - Retains high strength at high temp - Increases hardness - 12% chromium or higher is stainless steel |
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What are the advantages of adding molybdenum to steel? |
- Increases hardness and endurance - Decreases 'creep' - increases corrosion resistance |
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What are the advantages of adding Vanadium to steel? |
Promotes hardening ability, and increases ductility |
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What are the advantages of adding Copper to steel? |
Improves atmospheric corrosion resistance |
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What are the advantages of adding Lead to steel? |
Improves machinability |
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What are the advantages of adding Manganese to steel? |
Increases strength, hardness and resistance to wear |
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What are the advantages of adding Tungsten to steel? |
Retains hardness and strength at high temperatures |
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Why is copper a desired engineering material? |
- High electrical conductivity - High heat conductivity - High corrosion resistance - Tough - Ductile |
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What is brass |
Brass is a mixture of copper & up to 40% zinc
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What is brass mainly used for? |
Valves, fittings and bearing shells |
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What is bronze and what are some of the uses? |
Alloy of copper and tin, also used for valves, fittings and bearing shells |
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Why is aluminium desired for engineering? |
- Malleable and ductile - Good conductor - Good heat conductor - Highly resistant to corrosion |
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What are some of the alloys added to aluminium? |
- Copper - Zinc - Silicon - Manganese - Nickel - Magnesium - Chromium |
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What is white metal and what is it chiefly used for? |
White metal is tin and lead, it is mainly used for bearing materials |
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What is arc welding? |
The act of joining 2 pieces of metal together by means of an electrical arc |
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What are the temperatures produced by an arc? |
3000 - 8300 Degrees c |
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What is the purpose of electrode covering? |
To protect the bead of weld from the atmosphere |
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What determines the rate of electrode consumption? |
The current setting |
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What are the two types off current used in arc welding? |
AC and DC |
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What are the 3 power sources used for arc welding? |
1. AC - Transformer 2. DC - Generator 3. DC - From AC rectifier |
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Wha does the "E" mean on welding rods? |
Means its suitable for electric welding |
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What does the first 2 digits mean on a welding rod? |
Tensile strength eg. (60 means 60k lbs) |
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What does the third digit mean on a welding rod |
Weld position |
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What dies the fourth digit mean on a welding rod? |
Rod characteristics |
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What are the numbers that correspond to welding positions? |
1. All positions 2. Flat or horizontal (vertical surface) 3. Only in flat position 4. Down hand only (vertical surface) |
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What type of electrical current is preferred for welding? |
DC |
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What is straight polarity? |
The electron flow is negative |
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What is reverse polarity? |
Electron flow is positive |
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Briefly describe submerged arc welding |
Welding beneath a granular surface |
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Briefly describe braze welding |
High temperature solder not actually a weld that requires an oxy-acetylene setup |
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What are the four non-destructive weld tests? |
1. Visual 2. Liquid dye 3. Radiographic 4. Ultrasonic |
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Briefly describe a liquid dye penetrant inspection, and what are the 2 types of dye used? |
The 2 types are fluorescent and dye. The are simply put on the weld and cleaned off, and remaining will show defects |
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Briefly describe a radiographic inspection |
X-ray on one side and special paper on the other side, if theres holes in the wells it will trap some of the x-rays showing it on screen |
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Briefly describe ultrasonic inspection |
Same as radiographic but it is sound mesured |
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What is arc welding? |
The fusion of metal by the process of an arc. |
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What does the axis of weld mean? |
An imaginary line through the weld used as a reference point. |
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What does backfire mean? |
The retreat of a flame into a torch tip |
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What does backing pass mean? |
Going back over a weld again |
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What does backing strip mean? |
Things put behind welds to increase thermal capacity |
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What is a backing weld? |
A backing weld is a weld on the other side of a but joint weld to fill in any missing voids |
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What is a bare electrode? |
An electrode with no coating |
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What is a base metal? |
The metal to be welded or cut. |
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What is the bevel angle? |
The angle perpendicular to the surface of metal |
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What is boxing? |
The act of continuing a weld around a corner |
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What is carbon arc cutting? |
The act of cutting metal with the heat of an arc between a carbon electrode |
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What is coalescence? |
The fusion of 2 metals into one |
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What is a crater? |
The depression or hole at the end of a weld. |
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What is the lead angle? |
The act of pulling an electrode |
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What is porosity? |
The amount of pockets or voids in a weld. |
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What is post heating? |
The act of heating a weld after to slow the cooling process to prevent cracking |
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What is slugging? |
Filling weld areas with foreign material for filler |
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What is undercut? |
To deep of a weld in the corner weld |
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What is forge welding? |
Heating metals and hammering them together |
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What is oxy acetylene welding? |
Using an oxy torch to heat filler rod in a weld segment |
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What is the base metal? |
Base metal is the same as the welding rod
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T/F - Oxy acetylene welding is limited to thin materials? |
True |
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What are the bottle pressures for oxy acetalyne welding? |
Oxygen bottle - 15,400 kPa Acetylene bottle - 1,720 kPa |
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What is Acetylene absorbed in and why? |
Acetylene is absorbed in acetone because it is unstable by itself |
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Does oxy cutting burn metal and what temp |
Yes burn 870 degrees c |
