We are building a hopper out of 3/8 in. AR400 abrasion-resistant steel plate that will have vibrators mounted to it. I am wondering what GMAW filler metal you would recommend, along with any other information about welding this material.
Welding AR400 is not a difficult operation as long as you observe several issues.
First, filler metal should be low hydrogen good quality GMAW wires are low hydrogen. Typically, filler metal with less than an H4 rating is used, but it must not have rust or have been stored improperly. In general, an E70 series MIG wire such as ER70S-6 would be appropriate as long as you have no additional strength requirements for the weld. Staying with the lowest strength filler metal that meets your intended service requirements for the weldment is strongly recommended.
Secondly, the materials to be welded must be clean, dry and free of rust, millscale, or any other hydrocarbon-producing material.
Third, you should watch the total heat input that you use to make the weld. If you are welding two 3/8 in. pieces of AR400 together, you should keep the heat input per pass under 35 kj per inch. Heat input is calculated by using the following formula:
HI = (amps x volts x 60)/(travel speed x 1,000).
Generally, there is no need to preheat this material in this thickness range.
I am rebuilding a J.I. Case 580 backhoe bucket. The customer wants to use AR-400 abrasion-resistant steel for the bucket side plates and wear strips (heel bands) on the bottom. What stick electrode do you recommend to weld T-1 (ASTM A514) steel to AR-400 plate? The plates will vary from 3/8 in. to 3/4 in. thick.
A good quality E7018 or E7018-1 is a good choice for this application. (Remember that low hydrogen electrodes must be stored properly to maintain their low hydrogen characteristics.) Using a lower strength filler metal is generally preferred as long as it meets the mechanical requirements of the weldment. Lower strength filler metals produce lower residual stresses and reduce the chance for hydrogen-assisted cracking in both the A514 and AR400 materials. The types of welded joints typically used to fabricate buckets are lap and fillets. These joints can be oversized to generate more weld strength if desired. Typically A514 and AR400 materials are used as a wear surface and are not used as structural components of the bucket. The weld is used to hold the AR plate in place.
We have specified annealed carbon steel forging that has less than .35 percent carbon which is later welded to a mild steel plate. The annealed forging does not have adequate strength, so we are going to change our heat treating practice and normalize it. Are there any adverse effects to the weldability of the forging by making this heat treatment change?
The following recommendation is based on the limited information provided about the alloy: Changing the forging heat treatment from annealingto normalizing should result in little to no difference in the weldability of the material. The additional strength associated with the change to normalizing may increase the effect of restraint slightly on the weld. This can be rectified easily by increasing the preheat and interpass temperatures.
I am considering fabricating a structure and having several components galvanized after welding. My customer is asking if the heat from hot-dip galvanizing will affect the Charpy V notch properties of the weld. Any thoughts would be appreciated.
I do not have any information on the exact effect, but the American Galvanizers Association says the temperature at which galvanizing is done is around 815 degrees F. This temperature is below the temperature that is commonly used for stress relief usually 1,125 degrees F. The big variable is time. Time-at-temperature is what determines the amount of stress relief. This effect is not linear with temperature, but it takes exponentially longer with a lower temperature to get the same effect. The upshot is that it should not be in the galvanizing bath long enough to substantially alter the mechanical properties of the finished weld at this temperature range and if it was, Charpy V-Notch properties would only be affected minimally.
|This column is sponsored by Penton and the Lincoln Electric Co., Cleveland. Dave Barton is a senior welding engineer in the Application Engineering Group of The Lincoln Electric Co. He oversees welding procedure development for both new technology and existing products, performs failure analyses for customers, and serves as a consultant on welding application problems. Barton has been with Lincoln Electric for 21 years. Send your questions for Mr. Barton in care of WDF by e-mail to: firstname.lastname@example.org|