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4130 question for you guys....

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  • 4130 question for you guys....

    I posted on the main forum too, but I thought you motorheads might be able to help also. And seeing as how this project has something to do with motorsports, I figured it would be worth a shot.

    I'm building an engine stand for a buddies airboat, using 4130 tubing, 1" and 1.5" x .120 wall, using ER80S-D2 filler. Question is this, after completion he plans to have it powder coated. I'm afraid that the heat from baking the powder coat (450 F) is going to have a bad affect on the tubing and/or the welds. Do I have a valid concern? If so do any of you know of anyother rust preventive coatings (other than paint) that we might be able to use instead?

    Thanks in advance.

    Later,
    Kev

  • #2
    Originally posted by kevbooth View Post
    I'm afraid that the heat from baking the powder coat (450 F) is going to have a bad affect on the tubing and/or the welds. Do I have a valid concern? If so do any of you know of another rust preventive coatings (other than paint) that we might be able to use instead?

    Thanks in advance.

    Later,
    Kev
    No Problem. that's not enough heat to affect either the tubing or welds.

    Hank

    Comment


    • #3
      Kev,
      Glad you asked, good question. Over the years there have been found a couple problems with powdercoating 4130.

      1-Depending on the process, there is a chance for hydrogen embrittlement of the 4130 durring the baking process, slight, but there is a chance.

      2-Powder coat doesn't have any sacraficial elements in it, and along with its other properties makes it poor for corrosion prevention should the coating be chipped or otherwise broken.

      3-The powdercoat tends to hide cracks that may develop in the structure, and can elude routine inspections.


      One of the best processes for areas of high corrosion ( near salt water, humid areas ), is using a Zinc Chromate primer, or a Chromate Epoxy primer, topcoated with a single component enamel ( synthetic or acrylic ). Using a 2 part topcoat over a single part primer can lead to filiform corrosion, and is a no-no. Using a single part top coat means the coating is not cross-linked, and allows oxygen to get to the sacrifical elements in the primer, which prevents corrosion should the paint coating be chipped.

      www.aircraftspruce.com should have all the materials you need.

      -Aaron

      Comment


      • #4
        Go right one ahead and Powder coat away. Just about ever sprint car in the country is powdercoated and ever Super comp and super gas car I ever built was powdercoated as well. A few have hit walls hard and no powder coating job has made any of the cars weak in anyway.

        Comment


        • #5
          Originally posted by Aerometalworker View Post
          Kev,
          Glad you asked, good question. Over the years there have been found a couple problems with powdercoating 4130.

          1-Depending on the process, there is a chance for hydrogen embrittlement of the 4130 durring the baking process, slight, but there is a chance.

          <snip>

          -Aaron
          Hi,

          I'm just curious about the issue of hydrogen embrittlement. In my former life, about three careers ago, I worked as a Rocket Engine Technician at Rocketdyne when it was a division of North American Aviation. I later worked at Lockheed, Litton and Rockwell B-1. I was a technical writer for several years also. The reason I mention this is that during these various positions, I became aware that heat treating is/was used after welding and plating of components to drive off excess hydrogen to lessen the chance of hydrogen embrittlement. The processes to which I refer often specified as much as 12-18 hours in a large oven at something like 300 degrees. F.

          I also have a home-built powdercoat oven that is nearing completion. It's 2' X 3' X 6' inside and will be used for Motorcycle frames, wheels and so forth, among other things. I'm not a chemist or a metalurgist, just a little curious. Do you think that heat could cause embrittlement? I always understood that it would drive off hydrogen to relieve the parts. I sure wouldn't want to cause anything like hydrogen embrittlement.

          Synchroman, Curious in Sacramento County, California.
          Last edited by Synchroman; 07-06-2008, 11:30 PM.

          Comment


          • #6
            Originally posted by Synchroman View Post
            Hi,

            I'm just curious about the issue of hydrogen embrittlement. In my former life, about three careers ago, I worked as a Rocket Engine Technician at Rocketdyne when it was a division of North American Aviation. I later worked at Lockheed, Litton and Rockwell B-1. I was a technical writer for several years also. The reason I mention this is that during these various positions, I became aware that heat treating is/was used after welding and plating of components to drive off excess hydrogen to lessen the chance of hydrogen embrittlement. The processes to which I refer often specified as much as 12-18 hours in a large oven at something like 300 degrees. F.

            I also have a home-built powdercoat oven that is nearing completion. It's 2' X 3' X 6' inside and will be used for Motorcycle frames, wheels and so forth, among other things. I'm not a chemist or a metalurgist, just a little curious. Do you think that heat could cause embrittlement? I always understood that it would drive off hydrogen to relieve the parts. I sure wouldn't want to cause anything like hydrogen embrittlement.

            Synchroman, Curious in Sacramento County, California.
            Synchroman,
            I wouldnt be too concerned. It was only a couple specific companies materials that had problems, and that was years ago. Basicly the powders they used would release hydrogen when fused, but as I recall it was one of the older 500 degree plus systems. So like I said, there is a remote chance based on the process, however, a 12 hour bake at 350 F will usually drive it back out. From a service aspect I never found the powdercoats too desireable, but its more of personal taste. Hiding of cracks and corrosion getting under the material always bothered me.

            I forgot to add in my post about corrosion control, be sure the tubes are sealed by welding, and if they arent you may want to slosh them with boiled linseed oil or LPS3.

            -Aaron

            Comment


            • #7
              Just out of curiosity how closely engineered is this frame? Lots of things are moot if its a home brew deal or overbuilt, etc.

              Comment


              • #8
                Why 4130 for a STAND ?

                Comment


                • #9
                  Originally posted by Broccoli1 View Post
                  Why 4130 for a STAND ?
                  I wondered about that too. Apparently the "stand" will be the motor mount that holds the engine in place on the air boat when it's running and under way.....I guess that something less could be used unless there's a lot of stress and vibration.

                  Comment


                  • #10
                    Originally posted by Synchroman View Post
                    I wondered about that too. Apparently the "stand" will be the motor mount that holds the engine in place on the air boat when it's running and under way.....I guess that something less could be used unless there's a lot of stress and vibration.
                    my guess was engine mount as well. And by the sizing given, I was assuming a converted automotive engine. Something quite heavy.
                    -Aaron

                    Comment


                    • #11
                      Sounds better than a unit built in the backwoods with a buzz box, they went to the trouble of using expensive materials and are concerned with finish. I don't have ready access to powder coat but I got to agree with using paint finishes for the most part. Sand it up, epoxy primer and epoxy paint. I was trying to find some tubing pics but here is as near as it gets for the moment.
                      If I want it nice I sand then even sandblast all the grinding out sometimes, then scuff with Scotchbrite, blow the dust off and paint usually with Dupont Corlar epoxy primer followed by industrial Imron. As Aero said, often the color chips away leaving the primer, easy to fix. I am careful with installation, you cant help normal wear and tear but you don't got to beat the snot out of it putting it together. I always run a brite over after blast, it smooths it a lot, you can feel the difference and it knocks sand off. You can routinely get nearly auto grade finishes with a little practice and some acceptable place to paint.
                      Attached Files

                      Comment


                      • #12
                        I don't know how "engineered" the deal is, but...... As was stated before it is a motor mount for a converted automotive engine. 350 LT1 with bored and stroked to a 383 with a lot of perfomance mods. Makes around 450hp and 500 ft/lbs on and engine dyno. They gear it down with a 2.31 to 1 geared reduction unit to swing a 3 blade 12" wide kevlar prop.

                        I am basically reverse engineering the stand from what was previously in service. Just using better materials and triangulating some, while trying to reduce weight, where ever I can. I'm sealing all the tubes with welds any attachment holes will be sealed by welding "sleeve" into the holes.

                        I have to run coach a baseball game right now, but I'll come back later and give you guys a brief bio, maybe help clear up some of the "back woods" worries . I have a few more questions also.

                        Later,
                        Kev

                        Comment


                        • #13
                          Kev, I have powder coated many parts that are in the .058" and .065" wall thickness for snowmobiles and ATVs and have not had any problems with any distortion or problems of any kind. Same with chrome plating for that matter. I have heard of some problems with hydrogen embrittlement when chrome plating but after discussing with my plater he reassured me that it is not as much an issue as it used to be. I have been using 4130 extensively for about 7 years now. Mike.

                          Comment


                          • #14
                            Originally posted by zmotorsports View Post
                            I have heard of some problems with hydrogen embrittlement when chrome plating but after discussing with my plater he reassured me that it is not as much an issue as it used to be. Mike.

                            Im sorry but that is a blanket false statement by the plater. And a very dangerous one at that. Sounds like the words from someone who has overstepped their knowledge and capability. My guess is the plater doesnt know the mechanics behind HE.

                            Always bake 4130 (and others) after plating....always, if you rely on the part to never fail.

                            If you dont believe me, believe the ASME handbooks.

                            -Aaron

                            Comment

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