Chromolly vs mild steel - Interlocking Tube Clamps

I need some of these:

$43 Trail Gear Interlocking Tube Clamps - 180112-KIT

https://www.4wheelparts.com/Body-Pa...x?t_c=81&t_s=493&t_pt=4743&t_pn=TGI180112-KIT
I see better designs on ebay for cheaper. But i lean towards going with trailgear's product only because i assume this product will be available unchanged (same dimensions) and compatible with older bungs in the years to come. Is that a safe assumption?
I honestly don't like welding different alloys. I prefer mild steel tube clamps. Has anyone welded this product? any problems?
Addition of molybdenum and chromium is always cited as improving strength and sometimes corrosion resistance. I could see mild advantage to using the chromoly if it will resist corrosion of threads as the components will not always be attached to the truck. Is there really any corrosion resistance? i see chromolly bikes rot out.

 

Also, I will have to paint the interlocking components. It is not for a cage, just for a hang glider rack, not on in the winter. Are the tolerances on these such that paint will ruin the fit of the threads or the fit of the interlocking groves? What is an alternative?

 

Chromoly, typically 4130 4140 doesn’t contain enough chromium to provide adequate corrosion resistance. As for weldability, it’s classified as good I believe but in some cases requires pre heat and post heat. TIG is probably best process to use. A little bit trickier than mild steel

 

The tolerances are loose enough that paint wont cause and alignment issue. However, the paint may not stay in place or may cause it to stick when separating the joint. I am using some Ebay ones. There is also a company, I think TMR, that makes them with bolts on the same side, also some with integrated tubing section on one side. A little more expensive, but nice.

 

Thanks for the response @windsor and @Andre1080,

I just started (today) laying out how i am putting this together and marking what cuts to make.

I ended up ordering the Trail Grear ones simply because I predict they have a big enough customer base to demand the dimensions not change, so parts will be interchangeable in the years to come. But they are 2 or 3 times what some of the ebay people were selling for. I wanted the bolts on the same side but, not want i got.

I was and am still concerned about the welding of it to mild steel. I only have MIG (i am better at TIG). I will read up on preheating, unless you have some advice you care to share here. Thanks, Andre1080.

 

You did make sure it is for the correct wall thickness, right? Mine are 1 3/4 x .120 but I have to mill them down for my 1 5/8 x .134 tubing. I went MS on my tubing and my connectors (forward struts of cage are removable, still thinking the entire cage will be bolt in) for simplicity of welding. And since the relatively low corrosion resistance, all connections will be sandblasted and painted in POR15 type chassis paint.

 

I don’t know enough what your trying to do or the mig process in general to reccomend anything on my own but:
http://weldingweb.com/showthread.php?537841-Welding-chromoly-tube-connectors-to-mild-steel-tubes

 

Post some pics when you get it built.

 

Here’s a backup option for buying products you believe might become obsolete. Take measurements with calipers before you install. Do a sketch, write as much info as possible. If in 5 years the company no longer makes parts and you need a new one or two you can get a machine shop to make you some.

 

Thankfully, 1 3/4 x .120 is a common size and as long as there is an offroad or racing market, the parts should be available.
Here is the link for TMR if you decide you need bolts on the same side. They make interlocking and non-interlocking.
https://www.tmrcustoms.com/roll-cage-chassis/tube-clamps-flanges

 

Thanks again @windsor and @Andre1080,
Great advice and links. All were taken. Looking forward to reading the links tonight.
I will post photos... i am almost doing enough to warrant a build page. I will measure with calipers... good call.