The ability to properly add filler metal to the base metal is one of the most critical variables in welding.
Mismatching the base and filler metals can diminish the total tensile strength of the materials, reducing load-bearing capacities and perhaps leading to catastrophic events. You can follow four critical procedures to correctly match the filler metal to the base metal. The steps for this procedure are as follows.
Step 1: Determine the Base Metal’s Chemical Composition and Tensile Strength
When matching filler metal to base metal, the filler metal must be chemically compatible with the base metal. This data should be utilized to match chemical features and determine the strength of the structure to be welded, for example, the welding Base. Metals having tensile strengths of 60,000 psi will require electrodes with the same or better tensile strength to retain the strength of the base metal, e.g., E6010 or E7018 can be ideal for welding and sustaining strength in this situation.
Step 2: Identify the Welding Process
Knowing the welding procedure that will be used to join the metal is substantial to take precautions before any hurdles. This decrease is depicted in AWS’s Filler Metal Specifications chart. This chart depicts the grouping of filler metals with comparable chemical properties into the same specification, which is denoted by an A/SFA Number.
The AWS also records these specs by material and welding method, as seen below in the “AWS Filler Metal Specifications by Material and Welding Process” chart, which displays the reduction of possible filler metals by process and material employed.
Step 3: Determine the Welding Position
Another important factor to consider when choosing the right filler metal is the welding position. Some filler materials are molten and so fluid that utilizing the electrode at particular positions, such as vertical or overhead, could cause welder injury and hinder complete joint penetration due to the positioning of the materials being put together.
Step 4: How to Choose the Best Welding Electrode
The final and perhaps most important stage in selecting the suitable Electrode is to understand how to interpret the identification of the electrode’s designation. This identifying value is made up of an “E” for the electrode, followed by four to five numbers.
The first two or three digits refer to the minimum tensile strength of the filler metal; for example, the first three values “E70” indicate that the filler metal E7018 is an electrode with a minimum tensile strength of 70,000psi. The following digit represents the electrode’s usable position.
The value “1” for position implies that the electrode is good for any position. The value “2” indicates that the filler metal is molten and so fluid that the electrode can only be used in the flat position for all welding types and the horizontal position for fillet welds. The rating “4” implies that the electrode is acceptable for downhill welding.
The following value varies depending on the procedure, however, the last value in each case represents the Chemical/Operating Characteristics of the filler metal material. Examples of the identification system for three welding operations are shown below (SMAW, FCAW, and GMAW).
One of the most critical aspects of welding is matching filler metals to base metals. Knowing and understanding this information will boost safety during implementation as well as the safety of the product built over time. Horizon Marine Services delivers welding equipment to the market in response to the relevance of engineers’ needs. We are one of the largest welding machine suppliers in the UAE.
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