I am welding ASTM A514 steel (T-1), bar size 2.5 square by 18" long. It is welded to a ASTM A27 steel casting (.3% C). There are two each 3 pass, .5 leg fillet welds each about 8" long fastening the two parts, using Ultracore 712C FCAW wire. The parts are oven preheated to 250 F (I have done it at 175 F which gave the same results as 250 F). Upon sectioning the welds, the HAZ of the T-1 is Rc 40 (T-1 base hardness is Rc 22 ish), the deposited weld metal is only Rc 25. The T-1 HAZ seems high to me (Jominy end quench data for T-1, I believe is around Rc 40 for the first position.) Is Rc 40 too high? How do I bring it down? Is there something else going on?
Bill Z
Hello Bill, I believe that the filler wire that you are using is incorrect to begin with. The A514 has a tensile that is just a bit over 100,000psi, possibly more like 110,000psi, the wire that you are using is considerable lower than that. I believe that you need to be using at least an 80 series wire or probably more likely a 90 series wire. You should also consider paying attention to interpass temperatures and possibly post heating or thermal blanket coverage. My $.02 Regards, aevald
The casting has a very low tensil, 40-50 ksi and the final weld metal hardness is close to the T-1 tensile strength, around Rc 25. The interpass temperatures measured were not greater than 320 F (measured just off the weld edge after the final weld pass). AWS D1.1 discourages post heating as it may impair weld metal and HAZ toughness for T-1).
I am still stuck with the question, is Rc 40 too hard for HAZ in T-1.
Bill
Thanks for the clarifications Bill, sorry I couldn't be of any help. One other question here Bill. Is this a structural component or is this related to a piece of heavy equipment or machinery? I guess I'm curious whether this actually falls under D1.1. One other note I might add, I used to be involved in the manufacture of heavy equipment buckets and attachments, we used T-1 quite a bit for the cutting edges on the buckets and welded on cast adapters to hold the digging teeth on, when this was done we used a 250 to 300 degree preheat and welded with an E-71T1 wire, we had very good success and little breakage and loss in service. Regards, aevald
This does not fall directly under D1.1, I use that as a guide. The parts are structural in nature and are mounted on heavy duty trucks, on highway and off, mining vehicles etc. These parts take all the dynamic loads seen by the suspension systems. A part had failed due to other reasons and it was just luck that I sectioned the weld and then found the high HAZ hardness. Subsequent weld tests show it repeats itself. There are thousands of parts in service and have been for 15 years with little problem. I'm trying to clarify if the high HAZ hardness is even a problem - the weld is over designed for strength, but if it wasn't??
Thanks for the responses, everything helps.
-Bill
Hello again Bill, If in fact you find that this is an issue for you, have you ever considered looking into an alternative to using the A514 material. We have a fairly sizeable Rock Crushing and Material Handling Manufacturer in our area who has evolved the materials that they use to include a material known as Weldox 100, I believe that this material isn't as sensitive as the A514 grade of steel, it is much more easily formed and is more forgiving in it's weldability. Just a thought possibly worth looking into. Regards, aevald
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