Welding on factory frames Tua’h (11 Viewers)

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So I was curious and looked a bit further into the Austrailian regs (there are lots of them) - they do require an engineers signoff as expected, but there are some general requirements in there that may help the lay person - Queensland Code of Practice: Vehicle Modifications (QCOP) Code LH13: Light Vehicle Modifications for Chassis Alteration (Design Certification) - https://www.publications.qld.gov.au...3-chassis-alteration-design-certification.pdf. Relevant section are on page 6&7.

Elsewhere in there regs there are requirements around maintaining original flex in the vehicle design - i.e. keeping weld thinknesses under 10% to not create a stress concentration or increasing stress elsewhere. Makes me wonder about the wisdom of fishplating frames for strength and rigidity.
 
These are my thoughts on my questions. I’m not an expert and as always if you read something I wrote do your own fact checking never take my word for anything. I’m the definition of an armchair internet prick sitting in the peanut gallery but I will always try to be helpful and share what I believe to be true.

If it’s unknown mild steels, high-strength steels, ultra-high-strength steels do we assume at least (HSS) and proceed with best practices for that?

I will almost always assume at least HHS and preheat and cover after to help cool slowly, I don’t go out of my way with temp-sticks or follow a defined procedure other than getting some heat in it first then covering with a glove or something like that.

Pre heat and post heat always or not needed. If no pre heat should the moisture be chased out of the parent material before welding, if yes only acetylene or is propane okay?

Like I said above yes I like to preheat and I’ll chase the moisture line out as my indicator as to how much heat I have, I use propane but I’ve been told the moisture in propane will create issues in your weld and not a good source of heat for preheat.

Fish plates, needed or not needed. If needed when are they needed?

I like the Idea but I don’t do a lot of fish plating unless I feel the extra strength is needed like a previous repair failed and I’m stacking a weld over an existing weld or a complete frame section being added.

Supporting the area to be welded, needed or not needed. If needed what’s the best practice for a guy at home?

I feel like this is important if you don’t have the ability to check and adjust straightness after the fact and believe you are starting with a straight frame, I have two methods I use here in my home shop. I have three 2’X4’X3/8” plates I can bolt to the floor then use 2” and 3” adjustable tubes tack welded to the plates and frame (like cheap jack stands) to bolt the frame to the floor. I’ll do whatever work I do then cut the tacks from the frame, if the frame still lays flat on all 6 or more points that it was supported on before the work was preformed then I assume it’s still straight and move on, if not I address the issue while the (jig) is still setup. That is a pain in the butt to setup and to be honest I haven’t done it in a while but I do have several chunks of large I beam and I use them all the time to support something while welding and it’s the same process of scrap steel welded for bracing kind of thing. A dedicated frame jig or table would be fantastic but not in the cards for me space wise for the amount of that type work I do.

Welding start and stop locations, matter our not. If it matters what do we need to consider when planning out our weld strategy?

I’ve never given it much thought but @Cruisers and Co was talking about wrapping his welds and now has me thinking more about this.



Drilling holes and random spots on a crack repair, needed or not. If needed where do we put them?

I’ve always drilled a hole at the end of the crack because that’s what I was told to do and I’ve never questioned its effectiveness, I’ve also heard drill a hole every inch but I haven’t done that. Another thought I’ve had that would be interesting to hear what the experts say is if an automotive frame cracks not from an impact then it’s likely work hardened in that area. Would you address that with some annealing, extra fish plating beyond the area?

Vertical welding yes or no. If yes up or down, any special precautions?

I know it’s unavoidable but I try to keep it to a minimum and will make something on a diagonal at the very least if possible, I’ve always heard vertical up is the preferred method but very seldom do it and to be honest I haven’t given it much thought until we started talking about it here. I would come up with a secondary doubler plate or a different design all together if I have to put several vertical passes in a short span (I don’t have any facts to back this up but it FEELS wrong to have mutable vertical passes all together on an automotive frame)

Don’t judge me on spelling and grammar this morning it’s been a long couple days and I tried to bang this out quickly.
1.) I would say HSS High strength steel. Doubt very much it's mild steel especially the purpose this vehicle was built for. It would bend in half 🤔🧐😉.
2.) Pre-heat and Post heat I would say No! Material is not thick enough to consider this method! Heat to remove moisture! Yes! Both gasses are fine to remove moisture 🤔🧐😘.
3.) Fishplating! Yes, especially if the cut is vertical! Most chassis mods they recomend 45° cuts not vertical to maintain structural integrity.⁰ Fishplates are best on vertical cuts or to strengthen extende frames. 🤔🧐😉.
4.) Supporting the area to be welded is Critical in my opinion. It will minimize distortion and keep movement to a minimum while welding. For the Guy or Gal at home. Bolting or bracing the frame in the are to be welded will minimize joint alignment and distortion 🐖👈.
 
If you read thhe scope on page 3 of the JIS standard it's applicable from January 1st 1991 and foward. Nothing to do with 70s 🤔🧐
Yeah but let's not get drug in the weeds with a bunch of non-important information and lose track of trying to help each other like you said earlier.

So ol'Jack was the guys name that taught me so much early on and I believe he was a sailor or at least he cursed like one.
Anyway he would claim every time we had something foreign in the shop that "those MF'ing JAPS melt down old battle ships and razor blades to make their steel" and you better pre-heat before you weld it because you never know what you got.
I'm out in the shop now and thought I'd do the Jack chase the moisture deal and see what temperature you actually get the steel to and if it's appropriate for medium carbon steel.
20250731_131927.webp

Chuck of 5 or 6 inch channel and you can see the moisture form on the surface when you hit it with a torch.
20250731_132028.webp

Chase that moisture away and BAM that old SOB was bang on the money... 300 degrees is the starting temperature for welding low and medium carbon steel...
Thank you Ol'Jack..

I was looking for something that was helpful on pre-heat but I'm out in the shop on my cell not working on my project and found this that's close but not exactly what I was looking for. Anyway it has some interesting stuff if you get time to read..

 
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5.) Start and stop locations. I would consider this personal preference. This should be considered when developing you weld plan. Think about how you are going to approach it before diving in.
6.) Drilling holes on a Crack repair! Yes! This has been standard practice for years. When you drill the holes at beginning and end of crack and in between it prevents the crack from continuing at both ends and the in between helps with penet🐖👈ration 🤔🧐😳😮😲😘🤣🤣.
7.) Vertical welding! Yes! Up or down depends on the individuals expierience. Going up is easiest for most because the puddle does'nt build up as much. When going down you may have to increase your speed to keep the base metal from excessive heat and keep your weld in control. This is especially critical on Aluminum as the heat transfers more quickly. Most important thing is to be comfortable when welding! If your not your welds will not come out good🤔🧐😉😘.
 
Yeah but let's not get drug in the weeds with a bunch of non-important information and lose track of trying to help each other like you said earlier.

So ol'Jack was the guys name that thought me so much early on and I believe he was a sailor or at least he cursed like one.
Anyway he would claim every time we had something foreign in the shop that "those MF'ing JAPS melt down old battle ships and razor blades to make their steel" and you better pre-heat before you weld it because you never know what you got.
I'm out in the shop now and thought I'd do the Jack chase the moisture deal and see what temperature you actually get the steel to and if it's appropriate for medium carbon steel.
View attachment 3961153
Chuck of 5 or 6 inch channel and you can see the moisture form on the surface when you hit it with a torch.
View attachment 3961161
Chase that moisture away and BAM that old SOB was bang on the money... 300 degrees is the starting temperature for welding low and medium carbon steel...
Thank you Ol'Jack..

I was looking for something that was helpful on pre-heat but I'm out in the shop on my cell not working on my project and found this that's close but not exactly what I was looking for. Anyway it has some interesting stuff if you get time to read..

Imagine dat 🧐🤔😉
 
If you read thhe scope on page 3 of the JIS standard it's applicable from January 1st 1991 and foward. Nothing to do with 70s 🤔🧐
That’s not what it says, @bobm.

That’s the 1990 edition of JIS G 3113-1990.

For example: it makes reference to JIS SAPH 32 or JIS G3113 steel. They renamed the standards to when they transitioned to SI units, effective in 1991.

While we’re here, in chemistry, "P" represents the element Phosphorus, and “S” represents Sulphur.

IMG_8690.webp


IMG_8691.webp
 
you could look too.
I found it or at least something close enough for what we are doing here.
I believe mild steel is anything below .29%, .3 if we are rounding.
I don't know the grade Toyota used on the FJ55 frame so I'll list them all but it appears @gonzopancho is correct calling it low carbon steel.

SAPH310 .10%
SAPH310|SAPH310 STEEL |SAPH310 STEEL PLATE__Steel Supplier - https://gangsteel.net/product/Carbon/Q/BQB310/2012/0827/SAPH310.html

SAPH370 .21%

SAPH400 .21%

SAPH440 .21%

And one more with similar numbers..

They call the 440 High Strength and talk about frames and wheels so Wild A$$ guess we have SAPH440 frames??

I will continue to pre-heat all automotive frames I weld on and at .21% "C" if that's what we have then we are getting close enough that its probably not a bad idea.
Nice chat I learned something new, lets do it again tomorrow!
 
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Glad this came up after I did most of my rookie welding on my frame…all I have left is the FURD shock towers and I’m kinda skeerd to weld them on now 🙄

Stitch weld them rather than full send?

Anyways it’ll be fall before that progress happens, so :popcorn:
 
I've always been told hot to the touch or Iron hot and you'll be in that 200° to 300° range and that's close enough.
I'm actually in my office and not in the shop trying to do this on my phone, This looks like a handy pre-heat chart if that's something you want to do.
IR thermometers are a thing. Before that Tempilsticks were a thing (still are), and are specifically used for pre-heating.
 
All of this (waves hands) so far and no recommendation other than “pre-heat”… what absolute fun!

Heat input is a critical parameter in arc welding quality control, directly influencing cooling rate, microstructural evolutions, and mechanical properties of the weld/heat affected zone (HAZ), thereby governing residual stress distribution.

Please reference section 2.2.3 (p 13-14) of the work I posted first in this thread on why controlling your weld pool (“puddle”) size is important.

Preheating is about reducing the cooling rate, which modifies (moderates) the transformation products (primarily austenite & martensite), reducing weld and HAZ hardness. Depending on the metal being welded, it made reduce or eliminate hydrogen embrittlement, but this isn’t much concern with mild steels.

Rule of thumb is to pre-heat a width of at least 3x thickness. Get some crayons (Templisticks) if you want to do it right.

Hydrogen entrapment is also why we keep rod/filler dry, or even bake them before use.

200-300F (90-150C) doesn’t begin to encroach on any critical zone of a phase diagram, even for low carbon steels, but you will slow down cooling, which will help reduce stress risers. As much as 400F may be required on thicker low C steels. As you’ve noted, there are online calculators you can use.

IMG_8695.webp
 
Rule of thumb is to pre-heat a width of at least 3x thickness. Get some crayons (Templisticks) if you want to do it right.
Yes I have a few that haven't been seen in years, like you said IR is a thing.
At the end of the day we're trying help guys that might not have either, I do my own work and my mind was made up years ago on this subject unless I learn something new in the next few days here, and you pay several different guys to do your work and everyone of them do something completely different so yeah you might want to buy a box of crayons and send them to your guys!

All of this (waves hands) so far and no recommendation other than “pre-heat”… what absolute fun!
Neither one us us knew any facts and still don't about the exact steel used on our frames. You questioned my pre-heat comment when I said "if I don't know I assume the higher grade and pre-heat" (error on the safe side) and your reply was..
Why would you assume this given they weren’t used on 1970s era Toyota trucks and the welding properties are so very different?
If you're telling me the welding properties are so very different between .21% and .29% C steels then this is your chance to teach us all something new today!


Please reference section 2.2.3 (p 13-14) of the work I posted first in this thread on why controlling your weld pool (“puddle”) size is important.
Is using the “lower case e” technique what you would consider good “puddle” control?
Would you ever want to pass the arc back through the puddle? Unless you are making Instagram welds...
 
Thought this was closed for further discussion

You know me better than that, I don't get me feelers hurt if someone disagrees with me.. I look at it as an opportunity to learn something new and hopefully have open adult conversation and maybe someone else out there will learn something new too.



Although it’s hilarious it does no good to call me some childish name, declare you are the smartest guy in the room without any information or facts to back that up then lock or delete the thread before blocking me.. But as we know it happens.

I'm gettin ready to cut a piece of frame off and send it out to test it
You know what’s interesting about the SAPH440 steel is it has a fairly good amount of Manganese and I’m betting if that’s the correct material for the Toyota frame that could be why you and I thought the Carbon was higher.

With the reasonably high Carbon and Manganese I would think it would be springier than regular run of the mill low Carbon steel but we have experts that probably have a better answer..
 
welding and metallurgy classes so I can try to understand what the heck people are talking about?
I don't know much but I'll give it my best shot if you have questions about anything that we have been talking about..
Unless it's about the book "Metallurgy Of Welding 3rd Edition By J F Lancaster" Then we will defer all 3rd Edition Questions to @gonzopancho
 

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