F/C chassis integrity (2 Viewers)

[Draw 3D]

In refering to heat treated 4130 (considering that non-heated treated tubing is 4130 or 4130N normalized) the heat treated welded tubing in the future should be refered to as "Abnormalized."

Not trying to start an argument, but, that is an incorrect statement, the tubing has gone thru a heat-treat process during manufacturing to bring the tubing to the Normalized condition.

The word "heat-treat" has been misused to mean only raising the hardness above N-Condition, in actually, "heat-treat", can be anneal, normalized, artificial age, precipitation harden, or whatever. "Heat-treat" is a process for changing the metal properties harder or softer.

Also, any "engineer" who says you shouldn't use "heat-treated" 4130 chrome-moly in a chassis without asking what the hardness level is needs to go back to school.

 

[Randy]

Not trying to start an argument, but, that is an incorrect statement, the tubing has gone thru a heat-treat process during manufacturing to bring the tubing to the Normalized condition.

The word "heat-treat" has been misused to mean only raising the hardness above N-Condition, in actually, "heat-treat", can be anneal, normalized, artificial age, precipitation harden, or whatever. "Heat-treat" is a process for changing the metal properties harder or softer.

Also, any "engineer" who says you shouldn't use "heat-treated" 4130 chrome-moly in a chassis without asking what the hardness level is needs to go back to school.

The term was coined in conjunction with former members of the SFI Chassis committee after seeing test results taken from 14 A&B samples of tubing from a particular chassis builder. When you have elongation % numbers that range from 1.6 to 15.1, it really came down to the luck of the draw whenever you ordered a frame.

What would you say were acceptable elongation percentages? Somewhere between 1.6 and 7.6? 7.6 and 12.0? Or 12.0 and 15.1? Which of these would you prefer to use in your car?

The heat treating issue isn't all about hardness level. In fact, anyone with any knowledge of this has never said the heat treated tubing was taken to a point where it would be considered too hard or brittle or too soft for that matter.

I'm not sure what your point is about Rockwell testing and "engineers" going back to school. Just curious, what would you say is an acceptable hardness number for 4130N compared to say, a 4130 heat treated bottom frame rail, current SFI spec tubing with an elongation factor of 12.1% or higher. Would any targeted Rockwell number guarantee any elongation factor?

RG

 

[Bob]

Also, any "engineer" who says you shouldn't use "heat-treated" 4130 chrome-moly in a chassis without asking what the hardness level is needs to go back to school.

Unless I am mis-understanding what you are saying I need to go back to school.

You cannot weld heat treated tubing unless you heat treat it again to bring it back to spec. How can I do that if I don't know what the hardness is?

 

[Keith Burgan]

The term was coined in conjunction with former members of the SFI Chassis committee after seeing test results taken from 14 A&B samples of tubing from a particular chassis builder. When you have elongation % numbers that range from 1.6 to 15.1, it really came down to the luck of the draw whenever you ordered a frame.

What would you say were acceptable elongation percentages? Somewhere between 1.6 and 7.6? 7.6 and 12.0? Or 12.0 and 15.1? Which of these would you prefer to use in your car?

The heat treating issue isn't all about hardness level. In fact, anyone with any knowledge of this has never said the heat treated tubing was taken to a point where it would be considered too hard or brittle or too soft for that matter.

I'm not sure what your point is about Rockwell testing and "engineers" going back to school. Just curious, what would you say is an acceptable hardness number for 4130N compared to say, a 4130 heat treated bottom frame rail, current SFI spec tubing with an elongation factor of 12.1% or higher. Would any targeted Rockwell number guarantee any elongation factor?

RG

Robert,
read Randy's post again, specifically the third paragraph. The "heat treated" tubing is still well within the range of weldability. The last paragraph is also very relevant--the only way to test the modified tubing for suitability is with a check for elongation which is the critical factor.

Roo

 

[Bob]

Robert,
read Randy's post again, specifically the third paragraph. The "heat treated" tubing is still well within the range of weldability. The last paragraph is also very relevant--the only way to test the modified tubing for suitability is with a check for elongation which is the critical factor.

Roo

OK Roo I read it again but that's not what I'm talking about. If I have heat treated material and weld it the material will not maintain the same hardness. I was simply replying to the statement that you didn't have to know the hardness. You do have to know the material spec to return it to the hardened condition after welding.

I would want the same material condition (T0-T6) throughout.

 

[Keith Burgan]

Robert,
study the principles and materials used in the welding of 4130 frames (regular 4130N or the modified stuff) and you should understand a little better.

Roo

 

[Bob]

Robert,
study the principles and materials used in the welding of 4130 frames (regular 4130N or the modified stuff) and you should understand a little better.

Roo

Like I said I may be missing something. I will take your advice and check it out.

 

[Draw 3D]

Randy, the elongation percentages you list are the first I have seen published anywhere, and personally, I would prefer 12% to 15%. Were those numbers from the "heat-treated" tubes only, not near welds, and, were the tests done by an independent testing lab using accepted testing methods? I don't know that is why I ask.

Maybe I have misread posts stating you cannot use heat-treated tubing, but normalized tubing is tubing that has gone thru a heat-treat process to achieve the N-Condition requirements and is done during the manufacturing process.

The heat treating issue isn't all about hardness level. In fact, anyone with any knowledge of this has never said the heat treated tubing was taken to a point where it would be considered too hard or brittle or too soft for that matter.

Please pardon my ignorance, then what is the concern?

My statement about hardness is the harder the material, the less of elongation. Hardness testing is a non-destructive method for verifying mechanical properties, elongation testing is normally done thru destructive testing. Normalized hardness equates to around Rockwell 13 on the C scale.

And Bob, I don't know what you do for as a profession, and, since you took exception to my "engineer" statement, I will assume you are an "engineer" as I was before I left the aerospace industry. I learned that whenever a process or material is questioned for usability, you need to know all variables, in this case, what is the state of the mechanical properties. My original post was meant as any "engineer" who does not question the variables before giving a definite answer is not giving an educated answer.

Btw, You CAN weld slightly elevated 4130 properties, you will just lose those properties at the weld joint and in the heat affected zone. The weld joint, if properly done, will be in an annealed condition. The heat affected zone will have the transition from annealed to base material properties.

And Roo, from what I have read, wasn't McKinney reprocessing the tubing to N-Condition requirements?

Thanks to all,

 

[Bob]

And Bob, I don't know what you do for as a profession, and, since you took exception to my "engineer" statement, I will assume you are an "engineer" as I was before I left the aerospace industry. I learned that whenever a process or material is questioned for usability, you need to know all variables, in this case, what is the state of the mechanical properties. My original post was meant as any "engineer" who does not question the variables before giving a definite answer is not giving an educated answer.

Btw, You CAN weld slightly elevated 4130 properties, you will just lose those properties at the weld joint and in the heat affected zone. The weld joint, if properly done, will be in an annealed condition. The heat affected zone will have the transition from annealed to base material properties.

And Roo, from what I have read, wasn't McKinney reprocessing the tubing to N-Condition requirements?

Thanks to all,

Yep, I agree 100% and I had just PM'd Roo stating what you have just posted. I think we are all maybe mis-understanding what the other really means. You are right, aerospace is where it's at!

 

["Dr. Dirt"]

Paul Flies, Correct me if I am wrong but I now think I know who you are! Aren't you the APS employee who carried the book of conceptual drawings around for promotion of sponsorship possibilities? I believe I remember you from the old Mater Paul something or something Paul?

 

[Tom]

Folks, this is an interesting article that might answer a number of quesations.

::: Drag Racing Online ::: Material Considerations For Welded Steel Tubular Structures - 9/27/07

 

[Draw 3D]

Paul Flies, Correct me if I am wrong but I now think I know who you are! Aren't you the APS employee who carried the book of conceptual drawings around for promotion of sponsorship possibilities? I believe I remember you from the old Mater Paul something or something Paul?

Yep, that's me and my old mater name was Fuel Cars.

When I went to work for APS, I left the aerospace industry leaving behind the stress, the long hours and not nearly enough pay!

 

[Bob]

Yep, that's me and my old mater name was Fuel Cars.

When I went to work for APS, I left the aerospace industry leaving behind the stress, the long hours and not nearly enough pay!

Consulting is where the money is at Paul. If we didn't work long hours what else could we do?

 

[Nunz]

Paul, I remember when you posted under "Fuel Cars". My parents lives right near you in Avondale. Are you still building the altered? Any pics?

 

[Draw 3D]

Paul, I remember when you posted under "Fuel Cars". My parents lives right near you in Avondale. Are you still building the altered? Any pics?

Nunzio, yes I am still building the car. After my health got better recently, I resumed construction, but I'm going to run it in Top Dragster instead.

My signature has links to construction in process. I'm hoping to finish it the first quarter of '08, there is a lot to do.

Thanks for asking,

 

[Nunz]

Hey Paul, I checked out the updates. Looks like an exciting project, and I'm with ya' on the Top Dragster deal, it looks like a great outlet for fast cars running on a handicap. Your renderings are *****in', as always. Good luck with getting the car done, and I'm glad to hear that your health is better.