Are F1554 Grade 55 anchor bolts always weldable?

F1554 Grade 55 anchor bolts are not always weldable. The weldability of Grade 55 is a supplemental requirement referred to as “S1”, which must be specified. According to the ASTM F1554 specification under section S1.1, “This supplemental section, by chemical composition restrictions and by a carbon equivalent formula, provides assurance of weldability.” For F1554 Grade 55 to be considered weldable, it must conform to the following chemical requirements:

Heat Analysis Product Analysis
Carbon, max % 0.30 0.33
Manganese, max % 1.35 1.41
Phosphorus, max % 0.040 0.048
Sulfur, max % 0.050 0.058
Silicon, max % 0.50 0.55
ASTM F1554 section S1.5.1

In addition to the above requirements, the material must also have a carbon equivalent (CE) which meets certain requirements.  One of these carbon equivalent requirements is that for alloy or low-alloy steel, the carbon equivalent shall not exceed 0.45%.  The way to calculate this is to plug the chemical composition figures for a given heat lot of steel into the following formula:

CE = % C + (% Mn/6) + (% Cu/40) + (% Ni/20) + (% Cr/10) - (% Mo/50) – (% V/10)

For carbon steel, the carbon equivalent cannot exceed 0.40% using the following formula:

CE = % C + (% Mn/4)

When an F1554 Grade 55 anchor bolt has been specified to meet the supplemental requirement “S1”, the fastener must then be designated by a white paint mark on the side of the bar near the end to be encased in concrete. This is to designate that the anchor bolt can be welded.  Since F1554 Grade 55 anchor bolts need to be specified as being weldable, it is important to confirm that they do in fact meet the “S1” supplemental requirement prior to any type of welding. Because of this, Portland bolt has all of our raw material used to manufacture F1554 Grade 55 anchor bolts melted and rolled to meet this requirement whether the “S1” supplemental requirement is needed or not. As a result, you will never need to question the safety of performing a weld on any of our F1554 Grade 55 anchor bolts.

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    @Jamshid- Most Grade 55 is made to meet the S1 supplement for weldability. If your bolts meet that, then welding is allowed. If it does not then you’ll need to consult with the project engineer and have him/her decide if tack welding is acceptable in your application.

    @Wes- Smaller diameter (1″ and smaller) nuts of grade A563A are usually made from low carbon steel that is weldable. Larger nuts, even low strength ones, are usually hot formed from medium carbon steel (like 1045) and are not considered weldable. There are special procedures for welding special materials, but we are not familiar enough with those to have have any specific details.

    What kind of weldable coupler would develop the strength of F1554 Gr 55 or Gr 105 threaded rod? I assume you can get this rod fully threaded?

    @Alan- For the grade 55 rod, and heavy hex A563A coupler would be both weldable and would develop the strength of the G55 bolt. For G105 bolts, you would need to use a heavy hex A563 DH coupler, which is not weldable due to the heat treating process needed to achieve the high strength. Yes, both bolt grades are available as fully threaded rods in most sizes.

    @Lou- We do not believe there is a preheat requirement for F1554g55 bolts, but we are not welding experts, so you may need to contact someone more familiar with welding procedures.

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