Welding Techniques and Electrode Selection

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Questions and Answers

Describe two methods of striking an arc with an electrode.

Tapping and scratching

Why is it important to strike the arc only in the weld joint?

Arc strikes that are not covered up by the weld are considered weld defects by most codes.

What problems may result from using an electrode at too low a current setting?

Poor fusion and poor arc stability.

What problems may result from using an electrode at too high a current setting?

Wide and flat with deep penetration. Signup and view all the answers

According to table 4-1, what would the amperage range be for the following electrodes: 1/8" E6010, 5/32" E7018, 3/32" E7016, 1/8" E6011?

A: 70-130, B: 125-220, C: 75-130, D: 85-125 Signup and view all the answers

What makes some spatter 'hard'?

The spatter is hard because it fuses to the base plate and is hard to remove. Signup and view all the answers

Why should you never change the current setting during a weld?

It can cause arcing inside the machine resulting in damage to the machine. Signup and view all the answers

What factors should be considered when selecting an electrode size?

The skill of the welder, the thickness of the metal, and welding codes or standards. Signup and view all the answers

What can a welder do to control overheating of the metal pieces being welded?

Turn down the amperage on the machine. Signup and view all the answers

What effect does changing the arc length have on the weld?

Maintaining a constant arc length is important, as too great a change in the arc length will adversely affect the weld. Signup and view all the answers

What arc problems can occur in deep or narrow weld joints?

The arc is pulled to one side and not to the root. Signup and view all the answers

Describe the difference between using a leading and a trailing electrode.

A leading electrode angle pushes the molten metal and slag ahead of the weld, while a trailing electrode angle pushes the molten metal away from the leading edge of the molten weld pool. Signup and view all the answers

Can all electrodes be used with a leading angle? Why or why not?

Why do you ask me questions I do not know the answer to? I am just a poor and helpless computer program. Ask Mr. Dillon if you are so desperate for the answer. Signup and view all the answers

What characteristics of the weld bead does the weaving of the electrode cause?

It can control penetration, buildup, width, porosity, undercut, overlap, and surfacing applications. Signup and view all the answers

What are some applications for the circular pattern in the flat position?

Butt, tee, outside corner joints, and for buildup or surfacing applications. Signup and view all the answers

Using a pencil and paper, draw two complete lines of the weave patterns you are most comfortable making.

zzzzzzzzzzzzzzzzzzzzzzz, Done yet? No? Ok. zzzzzzzzzzzzzzzzzzzzzzzz. Signup and view all the answers

Why is it important to find a good welding position?

A good position is important for both the comfort of the welder and the quality of the weld. An awkward position can cause the welder fatigue, which leads to poor coordination and poor-quality welds. Signup and view all the answers

Which electrode would be grouped in the following F numbers: F3, F2, F4?

F2: E6012 and E6013, F3: E6010 and E6011, F4: E7016 and E7018. Signup and view all the answers

Give one advantage of using electrodes with cellulose-based fluxes.

There are no heavy slags that interfere with the welder's view of the weld. Signup and view all the answers

What are stringer beads?

A straight weld bead on the surface of a plate, with little or no side to side electrode movement. Signup and view all the answers

Describe the ideal tack weld.

Small and uniform to minimize its effect on the final weld. Signup and view all the answers

What effect does the root opening or root cap have on a butt weld?

As the width of the opening increases, the penetration of the weld increases. Signup and view all the answers

What can happen if the fillet weld on a lap joint does not have a smooth transition?

It can cause stresses that will weaken the joint. Signup and view all the answers

Which plate heats up faster on a tee joint? Why?

The stem of the tee heats up faster due to the fact that it cannot conduct heat away from the weld in as many directions. Signup and view all the answers

Can a tee weld be strong if the welds on both sides do not have deep penetration? Why or why not?

Yes. But only if the size of the two welds together equals the total thickness of the base plate. Signup and view all the answers

Study Notes

Arc Striking Methods

Two methods to strike an arc: tapping and scratching with the electrode.

Importance of Arc Location

Striking the arc only in the weld joint is vital as any unprotected strikes create weld defects according to most codes.

Current Setting Effects

Low current settings lead to poor fusion and unstable arcs.
High current settings result in wide, flat beads with excessive penetration.

Electrode Amperage Ranges (Table 4-1)

1/8" E6010: 70-130 A
5/32" E7018: 125-220 A
3/32" E7016: 75-130 A
1/8" E6011: 85-125 A

Characteristics of Spatter

Some spatter becomes hard by fusing to the base plate, making it difficult to remove.

Changing Current Settings

Avoid altering the current during welding to prevent internal arcing and potential machine damage.

Electrode Size Selection Factors

Consider welder skill, metal thickness, and welding codes/standards when selecting electrode size.

Overheating Control

Reduce the machine’s amperage to prevent overheating of the metal pieces being welded.

Arc Length Impact

Maintaining a consistent arc length is crucial; significant changes negatively affect the weld quality.

Arc Problems in Weld Joints

In deep or narrow joints, the arc may be pulled to one side, compromising the root penetration.

Leading vs. Trailing Electrode

A leading electrode angle propels molten metal and slag forward, while a trailing electrode angle pushes it backward.

Electrode Angle Usage

Not all electrodes can be used with a leading angle due to specific operational requirements.

Weaving Effects on Weld Bead

Weaving the electrode modifies weld bead characteristics, including penetration, buildup, width, porosity, undercut, overlap, and surfacing quality.

Circular Pattern Applications

Circular patterns are ideal for joints such as butt, tee, and outside corners, as well as buildup or surfacing tasks.

Tack Weld Characteristics

An ideal tack weld should be small and uniform to minimize its impact on the final weld.

Root Opening in Butt Welds

Increased root opening width leads to enhanced weld penetration.

Fillet Weld Transition

A rough transition in a fillet weld on a lap joint can induce stresses, weakening the joint's integrity.

Tee Joint Heating

The stem of a tee joint heats up faster as it has limited heat dissipation directions compared to other areas.

Strength of Tee Welds

A tee weld can be strong even with shallow penetration if the combined weld sizes match the base plate thickness.

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Description

This quiz covers important aspects of welding techniques, specifically focusing on arc striking methods and the effects of current settings. Understanding the proper selection of electrode size and the implications of spatter are also emphasized. Test your knowledge on key welding principles and best practices.