welding ar500 to mild steel

[kylerf150]

First of all hello everybody this is my first post.

Anyways I need to replace the bolster wear plate and king pin on my brother's cattle pot. Its all rusted and wore out. I plan on using 1/4 Ar500 plate but am unsure of the process needed to weld this type of steel. Also how well the welds will bond between the mild ( rusty ) steel and the Ar500.

From researching i have found that E7018 rod will work and that i should preheat to around 300 to 400 degrees. After i weld i should either postheat or wrap up to help the metal normalize. So if i postheat what temp should i get it up to and how slow should i let it cool. These welds are crucial they need to carry the whole weight of the trailer loaded ( 60k - 80k ). I'm not afraid of welding it I am just worried about the welds cracking out. I want to use the Ar500 because it is a high wear area but if it will compromise the integrity of the welds and mild steel would be a better choice i will go that route. I just purchased a trailblazer 325 today and will be using it to fix this trailer.

So
a. The process needed to weld Ar500 to mild steel?
b. What is the best rod to use?
c. Should i use mild steel plate instead of Ar500?
d. Any tips on using my new trailblazer 325?

Thank you very much and i appreciate the help/advice!!!!
Kyler

[JSFAB]

Why are you using AR 500 on the trailer plate??????????????

For most of us, it's far cheaper to replace worn out trailer plates than worn out 5th wheels mounted on the tractor.

[kylerf150]

Why are you using AR 500 on the trailer plate??????????????

For most of us, it's far cheaper to replace worn out trailer plates than worn out 5th wheels mounted on the tractor.

It's just what was recommended by a couple local welding shops to use the AR 500. Everybody around here wants 3k to do it so I told my brother I'd do it for him. I never thought about it that way I guess it would be allot cheaper to replace the plate if I do it myself every time. I think I will go with just a mild steel plate. That will make it easier.

Thanks kyler

[Tryagn5]

grease...

After your done welding it hand your brother a tube of grease and have him grease the fifth wheel plate which is also probably junk to. Lack of grease normally is the wear issue.
Kevin

[kylerf150]

After your done welding it hand your brother a tube of grease and have him grease the fifth wheel plate which is also probably junk to. Lack of grease normally is the wear issue.
Kevin

Haha. He just bought the trailer sight unseen and was told it was ok and ready for work. Not the case thats for sure all four corners are rusted out from the inside out. We will grease the h#!! Out of it though.

Anyways thanks for the help guys

[JSFAB]

When you buy the kingpin, make sure you are getting one with the correct shoulder to fit the thickness plate you are using.

[Portable Welder]

I agree with JS Fab, Replace the pin and verify the length is proper for your 5th wheel plate.

I also would use mild steel.

I have a trailer at my shop that is for onsite liquid storage and I to have to replace the plate and pin because they move them around on the job site with heavy equipment and the loader has concave the plate.

I'm charging $ 2,100.00 for this job.

[kylerf150]

I agree with JS Fab, Replace the pin and verify the length is proper for your 5th wheel plate.

I also would use mild steel.

I have a trailer at my shop that is for onsite liquid storage and I to have to replace the plate and pin because they move them around on the job site with heavy equipment and the loader has concave the plate.

I'm charging $ 2,100.00 for this job.

Well thanks for all the help guys. I got it done. We had to replace all the beams, I'm surprised it pulled a load of cows last weekend! I did get the right size plate and kingpin, the kingpin sticks out 84mm which from what i researched is right on.

Here's some pics ..