Arc Welding Processes 4001

The three factors that interfere with joining are surface contamination, surface roughness, and

crystallographic alignment

The three general methods to overcome joining barriers are heat, pressure, and

atmosphere control or flux[cite: 1]

The typical power intensity range of fusion welding heat sources is between 0.001 and

1 MW/cm2[cite: 1]

The approximate power density of arc welding is less than

10^4 W/cm2[cite: 1]

Point heat-source power densities of at least

1000 W/cm2 are necessary to melt most metals[cite: 1]

Power densities above 10^6 to 10^7 W/cm2 vaporize metals within microseconds, resulting in

hole drilling[cite: 1]

In arc welding, less than

50% of the heat generated enters the plate[cite: 1]

In arc welding, less than

20% of the heat generated is used to fuse the metal[cite: 1]

In oxyacetylene welding, less than

10% of the heat generated enters the plate[cite: 1]

In oxyacetylene welding, less than

2% of the heat generated is used to fuse the metal[cite: 1]

The ratio of depth-to-width of a molten pool is

Using the planar heat source formula for AISI 1025 steel, the melting time for oxyacetylene flame is approximately

3 seconds[cite: 1]

Using the planar heat source formula for AISI 1025 steel, the melting time for arc welding is approximately

0.05 seconds[cite: 1]

Using the planar heat source formula for AISI 1025 steel, the melting time for resistance welding is approximately

0.3 ms[cite: 1]

Using the planar heat source formula for AISI 1025 steel, the melting time for an electron beam is approximately

3 µs[cite: 1]

Compared to a planar heating source, a point heating source needs

2 to 5 times more time to melt material due to 3D conduction[cite: 1]

Welders begin training on the oxyacetylene process because it is inherently

slow and does not require rapid response time[cite: 1]

Processes like laser and electron beam welding cannot be performed manually because their weld pool must be

automated[cite: 1]

The non-melted area of metal that has undergone changes in material properties from exposure to high temperatures is the

Heat Affected Zone (HAZ)[cite: 1]

The HAZ width can be estimated from the process interaction time and the material's

thermal diffusivity[cite: 1]

The HAZ grows during the heating stage at power densities below

10^4 W/cm2[cite: 1]

In general with arc welding processes, HAZ width is reduced by lower

heat input (or increasing weld speed)[cite: 1]

Among the common arc welding processes, the highest weld deposition rate is achieved by

SAW[cite: 1]

Among the common arc welding processes, the lowest weld deposition rate is found in

GTAW[cite: 1]

Two common methods to increase GTAW deposition rate are automating the process and using

auto-feed hot wire GTAW[cite: 1]

Two common methods to increase GMAW deposition rate are

tandem GMAW welding and Hyperfill[cite: 1]

In the project management Iron Triangle, the three vertices are time, cost, and

quality[cite: 1]

The three basic principles to consider when preparing metal for welding are cleaning,

proper fit-up, and grooving[cite: 1]

Impurities like oil, grease, paint, and rust must be removed from joint edges to a distance beyond the

heat-affected zone[cite: 1]

Welding over surface impurities may lead to arc instability, contaminated welds, pores, cracks, and

inclusions[cite: 1]

Soft materials like aluminum and copper should not be prepared with improper grinding wheels because they become impregnated with

abrasive particles[cite: 1]

Abrasive particles embedded in soft metals during grinding cause weld contamination and excessive

porosity[cite: 1]

Machine cutting fluids containing

sulfur can create cracking in nickel alloys[cite: 1]

Joint gaps between metal surfaces for thin wall tubing or pipe should not exceed

half the thicknesses of the metals[cite: 1]

A backing plate made of

copper will prevent the weld from fusing to the plate[cite: 1]

In a single-pass weld diagram, the top of the weld is the

face[cite: 1]

In a single-pass weld diagram, the edges where the weld meets the base metal surface are the

toes[cite: 1]

In a single-pass weld diagram, the depth of penetration is the

root[cite: 1]

In a single-pass weld diagram, the depth of the weld is the

throat[cite: 1]

A double-V groove weld preparation commonly utilizes a

60 degree groove angle with a 1/8 in. root face and 1/8 in. root gap[cite: 1]

The final wide weld bead that covers across the groove angle is called the

cap or wash bead[cite: 1]

Compared to single-pass welding, multi-pass welding takes more time and increases the possibility of

weld defects including porosity and contamination[cite: 1]

Single-pass welding can cause significant distortion because of the large mass of molten metal and a larger

HAZ (area of recrystallization)[cite: 1]

Non-formally trained personnel who operate equipment and know process tricks are termed

Operators[cite: 1]

Trained professionals who master the skilled trade of welding over decades are

Technicians[cite: 1]

Personnel who possess cross-training combining technician skills and engineering principles are

Engineering Technologists[cite: 1]

Magnifying lenses inside a welding helmet are measured in units of strength called

diopters[cite: 1]

For good weight distribution and posture, a welder's feet should be placed

shoulder width apart[cite: 1]

When welding vertical joints, a steady rest is achieved by bracing the non-dominant elbow slightly higher than the

shoulder[cite: 1]