nccer unit 8. a smaw electrode has a wire core coated with ______. the wire core transfers the...

SMAW- ELECTRODESNCCER Unit 8

SMAW ELECTRODES A SMAW electrode has a wire core coated with ______. The wire core

transfers the current to the workpiece.

The arc melts the metal core, flux coating, and the base metal at temps over _____ degrees.

The wire core mixes with the melted ______________, which then forms the weld.

ADVANTAGE OF FLUX Gives off a ___________ that

protects the weld from impurities.

Cleans and _________ the metal

Stabilizes the arc and reduces __________.

Forms a slag covering that further protects the weld.

FLUX Some flux coatings have

powdered metal and alloying elements in them. This powdered metal adds ________________ and helps improve the _____________ of the weld.

These elements change the chemical composition and strength of the weld metal.

AWS FILLER METAL SPEC SYSTEM The most common welding electrodes are discussed in the _______

(Specification for Carbon Steel Electrodes for SMAW welding) and ________ ( Specifications for low-alloy steel electrodes for SMAW welding).

Electrodes in ______ are used to weld mild carbon steel.

Electrodes in ______ are used to weld low alloy, high strength steels.

NUMBER SYSTEM The classification system for electrodes uses the prefix E followed by four

or five numbers. This is printed on each electrode near the end of the rod.

The number system is as follows: E- stands for ___________ The first two numbers, multiplied by 1,000 represent the ___________ in square

inch of the weld. The third number indicates the possible welding ___________

1= _______________ 2= flat and horizontal only 4= flat, horizontal, overhead, and vertical positions

The fourth number represents the special characteristics of the flux coating and type of current required.

MANUFACTURERS CLASSIFICATION All electrodes used for code work

must have the AWS classification number printed on them as well as on the ___________ in which they are shipped.

Each manufacturer must also include the __________ for their product.

ELECTRODE SIZE Electrodes come in standard

sizes, usually ranging from ___________ in thickness.

Typically come in ____ and ___ pound cans

Number of electrodes in a can vary based on the thickness and length of the electrodes.

ELECTRODE GROUPS Electrodes are grouped into _____

different types based on their general characteristics: Fast freeze Fast fill Fill freeze Low hydrogen

FAST FILL ELECTRODES Fast freeze electrodes are all position electrodes that provide deep

____________.

The weld bead is flat with distinct ripples and the light slag coating can be hard to remove.

The arc is very easy to control which makes this electrode good for _______________________ welding. Electrodes in this group include….. E6010, E7010, and E6011

Typical use includes: Vertical up and overhead plate welding Pipe welding Weld joints requiring deep penetration Sheet metal welds

FAST FILL ELECTRODES Fast fill electrodes have powdered _____ in the flux, which gives them high

deposition rates but requires that they be used only for ______ welds and __________ fillet welds.

Have shallow penetration and excellent appearance with almost no splatter. The slag is also very easy to remove.

These electrodes have a __ as the next to last number… E6027, E7024, and E 7028 rods are typical.

Typically used on plate more than ¼’ inch thick and flat and horizontal fillet welds and also lap welds.

FILL FREEZE ELECTRODES Fill freeze electrodes are ________________electrodes that are commonly

used for vertical and flat welding.

Have medium deposition rates and penetration and are excellent for sheet metal. The weld bead ranges from smooth and ripple free to even with distinct ripples. Has medium slag covering that is easy to remove.

Electrodes include E6012, E6013, and E7014. Typically used for vertical fillet welds, joints having poor fit up in the flat position, and general purpose welding.

LOW HYDROGEN ELECTRODES Low hydrogen electrodes are designed for welding high sulfur, phosphorus,

and medium to high carbon steels which have a tendency to develop ____________ and __________ under the weld bead due to hydrogen that is absorbed during welding.

Electrodes in this group include E7015, E7016, E7018, E7028, and E7048. Typical application includes… X ray quality welds Crack resistant welds Minimized porosity Welds requiring 70,000 psi Multi pass welds in all positions

LOW HYDROGEN If hydrogen is present, it will create __________. The greatest source of

hydrogen is water moisture, which is composed of oxygen and hydrogen.

Low hydrogen electrodes are carefully manufactured to eliminate ____________ in the flux coating.

If low hydrogen electrodes are exposed to the atmosphere, they will begin to absorb moisture and no longer be low-hydrogen. For this reason, all low hydrogen electrodes are shipped in hermetically sealed metal containers. Once opened, these electrodes must be stored in a _______________ to keep moisture out.

ELECTRODE CONSIDERATION If there is a WPS for the weld to be made, the filler metal (electrode) will be

specified. The filler metal specified in the WPS must be used.

The filler metal should match the base metals _________________________ and mechanical properties. These properties of the base metal can be obtained by referring to the _________________________________.

BASE METAL THICKNESS Normally , an electrode that is _____________ in diameter than the

_____________ of the metal to be welded is used.

When welding sheet metal, use a E6013 electrode due to its shallow penetration.

On thick metal, use a E6010 or E7010 electrode on the root pass for its deep penetration on a root pass.

ELECTRODE STORAGE Electrodes must always be kept

______. If the flux starts to absorb moisture from the atmosphere then weld defects begin to show up. Some of these defects may not be visible to the naked eye.

_________________ electrodes pick up moisture faster than any other electrodes.

CODE REQUIREMENTS All welding codes require

electrodes with a low hydrogen coating to receive special handling. They must be shipped in sealed containers and be stored in special ovens at temps of ________ degrees.

Once these electrodes are removed from the oven, they can only be exposed to the atmosphere for a short period of time. This is known as their ____________.

ELECTRODE STORAGE All electrodes other than low

hydrogen electrodes must be shipped in moisture resistant containers.

The electrodes must not be used if their coatings are damaged or if they have came into contact with _________________.

STORING ELECTRODES CONT… Always store electrodes in a _________________ storage area.

Never store directly on the floor. This can cause the electrodes to from condensation.

EXPOSURE TIME The time that an electrode can be exposed to the atmosphere is limited

and depends on the electrodes exposure time. ( the amount of time that the electrode can be out of the oven before it begins to absorb moisture)

Samples of electrodes being used at a job site are often collected by quality control for _________________.

If high moisture content is found in the electrodes, then the welds must be _____________.

DRYING ELECTRODES Electrodes that exceed the maximum exposure time can be dried again

only __________.

After that they are no longer useable.

TRACEABILITY REQUIREMENTS A WPS on a job site normally specifies the type of electrode that must be

used. Once the weld is made, there must be a way to trace and document it.

______________ requirements vary according to client requirements and specifications.

One of the most common requirements for traceability can be found in the ______________________________________, Section II, Material Specifications.

This section lists acceptable base metal and filler metal combinations.