Somewhat. Depending on what your application is there may be several other things needed. First and foremost, you will need a "preliminary" welding procedure specification for the welder to aim towards, then you will need to stand by and record the ACTUAL variables used when performing the test weld(s). The test specimen then becomes known as a PQR Coupon which is subjected to mechanical tests; normally 2 tensiles and 4 bends. There may also be impact testing and hardness test required. Once the tests have been made (and are successful) the welder who ran the test coupon may then be considered qualified to weld in the position the test was run. Other welders will need to test to the WPS which has the PQR annexed with it...
Unless I'm mistaken, 1018 is a carbon steel with C=.15-.20, Mg=.60-.90, P=.04, and S=.05. (single digits are maximum allowable) It is a low carbon, general prupose steel and the heat treatment has minimal effects.
The 4140 is an HTLA with C=0.38-0.43, Mn=0.75-1.00, Si=0.15-0.35, Cr=0.80-1.10, andMo=0.15-0.25. The HTLA steels (4140) have high hardenability and are susceptible to hydrogen cracing in the weld metal and the HAZ. Low hydrogen welding procedures must be used with sufficient preheat and interpass temperature to prevent hydrogen cracking.
The thickness of the parts to be welded will determine the preheat and interpass temperature. For thicknesses up to 0.5 in. the preheat and interass temperature should be 350F. For thicknesses of 0.6-1.0 in. the preheat and interpass temperature should be 450F. For thicknesses of 1.1-2.0 the preheat and interpass temperature should be 500F. The PWHT required immediately after welding depends on the preheat and interpass temperature and any subsequent processing prior to hardening. The matching filler metal for the 4140 is listed in AMS specification 6452. Naturally, the parameters will depend on what welding process you decide to use.
Chuck
Great answer Chuck! You always come through for us!
Jon,
If I'm ever up in Michigan, I owe you a big dinner.. :)
Chuck
Hey Chuck, if you ever get up to Michigan it would be great to meet up with you!
I have first dibbs on him for BBQ at Porter Street in northern Ca. Great article on HAZ in the journal.
Dennis
By -
Date 07-31-2005 00:13
Dennis,
As a matter of fact, I'm tentatively scheduled to be in the S.F. area and the NAPA Valley area around Oct. if things go as planned to do a Stainless Seminar for some customers. Hey, I'll buy you a cool one !! Thanks for the compliment on the article.
Chuck
Chuck, Thank you so much for responding to my post and I'm sorry I haven't gotten back to you sooner. Do you believe that we could use the following procedure and qualify:
4140H is 2-1/2" Round (Large, I know), CA/AL TRT FG LP ANNEALED CD.
Stick weld 1" Round 1018 perpendicular (to make a pin) to the end of the 2-1/2" round 4140 (square cut) with 7018 rod (1/8").
Preheat- min 400 deg, probably around 500
No PWHT, wrap in ceramic wool for 5 days
Interpass temp 450 deg
Will the heat affected zone of the 4140 be susceptible to cracking or will there be enough Cr-Mo alloy within the weld metal to give it substantially higher strength. The part of the pin under load will be the shaft of the 4140 and not the connection. The 1018 bar is just to keep 4140 shaft from falling out of hole.
The 4140 is always "susceptable" to hydrogen cracking in the weld and HAZ, but with the sufficient preheat and interpass temperature you should not have a problem with the procedure you submitted. If you use a 500F for your preheat and interpass temperature you should be fine. If you are wrapping it in ceramic wool for 5 days to counteract any delayed hydrogen cracking, I don't think you will need the 5 day cooling period. But, that is up to you. The 4140 has very little Cr and Mo, so that is not what is going to make or break you in the HAZ. I'm confident you will be fine.
Chuck
Chuck,
One other question, I have some other folks telling me that the filler material is specified under AMS 6457 alpha and that the 7018 with a tensile strength of 70k lbs/sqin is not sufficient for the 4140 w/ around 100k tensile strength. Those strengths were given to me and on my cert it is not specified as to the strength. Only that it is annealed? Any thoughts?
Dan
Based on your application, the 7018 should be fine, but if you are concerned, to to a 80xx or 90xx series. The key is to use a low hydrogen filler. Annealed is also good. AMS 6457A is the matching filler for 4130. For 4140 it is AMS 6452.
Chuck
Chuck- Along those lines, I am welding X52 WOL to a 4130 run of pipe. Trying to find out where it says I can use the weaker of the Tensiles to weld against the 4130 High Yield material. There is to be a spec break there.
COMMENTS?
Thanks,
Lee
I would venture a guess you should be able to find that in ASME IX.
Hi Lee
I'm not sure you are going to find where it says you can use the weaker of the 2 steels. It probably won't say you can't, either. The main thing is to make sure your filler is of the low-hydrogen type. Also, it is prevalent that you use the proper preheat to avoid the susceptibility to hydrogen cracking in the 4130. Of course you can use a 7018 for the X52, but that is under-strength for the 4130 (an HTLA material). The filler metal for the 4130 is outlined in AMS specification 6457A. But for steels of different tensiles and yields, I would certainly recommend the filler closely matching the higher. I would think that a 90 series filler would suffice unless you intend to use the ASM specification filler that is the same chemistry as the 4130.
Chuck
Chuck-
Thanks for reply.
Even though the contractor has a qualified procedure to use this would you still recommend me going to the higher of the two strengths? I am in the position to accept or not the procedure but I need a good CODE back reason as to why....
My response to their question about the 70,000 tesile was.... "If you have a "Qualified" Procedure and it is at a spec break (they do not care enough to run 4130 to a flanged joint). ... then I cannot stop them from doing it. (Right?) Because I cannot find, in Sec IX, where it says it.
Now for "Thickness" Sec IX goes into detail.... not strength.
Thanks Again,
Lee
If you have a qualified PQR, qualified by lab testing and it meets the requirements of the spec, then I guess that is acceptable. From a metallurgical standpoint, it is good welding practice to use the higher strength filler, especially in cases where the possibility of hydrogen cracking might be present. The 70,000 tensile filler is a minimum tensile, but so is the 90,000 tensile filler. I believe we can agree that the Code book is a book of minimum requirements. Upgrading to higher standards is up to the fabricator to choose and qualify by testing. In this scenario, I would still use the higher filler just my own satisfaction, but it's not up to me.
Chuck
Chuck- This is my first day on the Board. You seem very knowledgeable and I thank you for your time... I know how valuable it is.
I have 28 years in the business of QA for Chevron and others. This is the first on this (as simple as it may seem). I just got stumped . Thanks for un-stumping...HA!
Lee
By -
Date 08-10-2005 16:45
Lee,
Not a problem. I will be in meetings the rest of the day, but if you have any more questions, I will address them later this afternoon. Thank you.
Chuck
Lee,
Remember that the Code Book gives minimum requirements. It is certainly acceptable to upgrade to higher strength filler material if you feel it is warranted. In your case it might be good to just consider if the 70K tensile is sufficient to counteract any possibility of hydrogen cracking from the HTLA (4130). Usually, but not always, fabricators will use the higher strength filler of the 2 metals just to insure more protection against possible cracking.
Chuck
Can yo tell me, in Sec IX, where it may mention that the engineer can reject the procedure for use on the project. Just for the reason that he does not like it?
I knoow that I have rejected them in the past and the specification usually would take care of any doubt that I could or could not reject something.
My boss asked where, in the code, it allows the engineer to reject based on the fact that he just does not like the IDEA of using the lower tensile of the base metals for filler.
QW-153.1 (b) allows it, even though we all know it may be suseptable to cracking.
Thanks Again,
Lee
Actually, here is the cert information: CA/AL TRT FG LP ANNEALED CD. BHN 196/248 JOMINY J12=39 MIN, J32=30 MIN
ASTM A304-96, A331-95 & A29-99.
Lee, if you are working on ASME or API fabrications (and since you discuss a run of pipe, I assume one or the other of the above would apply)... you will find your answer under ASME Section IX, QW-153.1 which states (in part) that in order to pass the tensile test, the specimen shall have a tensile strength not less than (b) the minimum specified tensile strength of the weaker of the two, if base metals of different minimum tensile strengths are used.
Hope this helps! ;-)
That helped... Could you respond to the reply I made above.
Thanks,
Lee
Lee, I don't believe Section IX would talk about the engineer accepting or rejecting a procedure, you would likely find that in the constructing or fabrication codes like B31.1, B31.3, ASME VIII, AWS D1.1, etc.
I am having fun with this one. I always assumed that we could accept or NOT a welding procedure just because we did not like it. The specs usually give us that option.
I am looking in B31.3 for the place where it gives the engineer the right to accept or reject a welding procedure just because it is not preferred and have had problems in the past with it.
IDEAS?
Thanks,
Lee
I don't have a B31.3 but used to work with it quite extensively. If I were to answer you face to face, I would probably tell you that engineers don't "normally" reject a procedure just because they may not like it, there really should be some technical reason for it. Sorry, I just seem to be picking up a "game playing" mentality and hope I'm wrong...
That's OK I am use to the game. This is what I have done all my life. My family of inspectors go back 4 generations. HA! But, for the sake of discussion and explaining better... lets try an analogy.....
For example. lets just say, (not really) We are installing a Pipeline, offshore.... the contractor wanted to use a "qualified" wire (GTAW) procedure. Well... I know I do not like the procedure for that application (wind, etc.) and would rather use a SMAW process for SEVERAL reasons.
What could I say? Nothing?
Thanks,
Lee
Lee,
I think that, in this case, you would reject the process, not the procedure. I don't think an Engineer can reject a qualified procedure if it is proven by testing according to the Code. I think he can reject the process if he has reason to think it might not be applicable for certain conditions. Once a procedure is qualified, it is qualified.
Chuck
I guess to be clear. The procedure IS accepable. The engineer cannot reject the procedure. We just do not believe it to be acceptable for this project.
More specific, the X52 welded to the 4130 pipe (B31.3). Sec IX 153.1 says you CAN use it. However, some history along with comments from this post, makes me not want to use it. I would rather use the electrode with the higher tensile strength.
Not sure where I stand as per the code. Specs are a different story.
Lee
Lee,
We might be into a game of semantics here. I think the Engineer can reject a procedure if the welding process within that procedure is not suitable for the conditions it is to be used in. Example: GTAW qualified procedure might not be suitable for an offshore, outside welding job in the wind. He can reject that procedure due to the welding process incorporated in that procedure. I guess you can say he is rejecting that procedure, but based on his good judgement that the process used in that procedure is not acceptable for whatever his reasons. I also agree, as stated in previous posts, that I would rather use the higher tensile electrode on the 4130 pipe. Again, the Code Book is a book of "minimum" requirements. You can go up, but not down.
Chuck
I think you are right. Sometimes, writing is difficult to get a point accross. However, I am glade we agree on your last staement. It makes me all warm and fuzzy...
I found some things in B31.3 and some general company specs. I did not have access to the Esso specs and needed some ideas. Thanks to all who helped.
Have a great day.
Lee