welding 316l with c content less 0.025%

By - Date 09-27-2005 13:43

Jimmy,
It is definitely true that using a lower C content is to your advantage. Sensitization is a function of time, temperature, and carbon content in stainless steels. A 316L with a C content of 0.030% will become sensitized in around 7 hours when held at temperatures of 1000F. A 316L with a C content of approximately 0.025% will sensitize in approximately 30 hours when held at the same temperature. Look at it like this; a 316 with a C content of 0.062% will sensitize in just a matter of minutes when held at 1400F. That is why careful monitoring of the time, temperature, and C content is vital, since some of the regions of the HAZ will be in this temperature during the welding process. But, on the same hand, normal welding cycles are typically too short for any detrimental sensitization to occur. Also realize that the chromium carbides by themselves do not lower the corrosion resistance, it is the chromium depleted region immediately adjacent to the carbides that lower the corrosion resistance. In closing, using anything with a C content of 0.03% and lower should give you plenty of time to complete the welding before the onset of sensitization using normal welding cycles.

Chuck

By jon20013 (*****)

Date 09-27-2005 14:34

Chuck, good analysis on the welding portion.

What the customers/owners are concerned with in these cases is service conditions, thats why the lower C. As You know, there many, many service issues one must be aware of when using stainless steels.

By - Date 09-27-2005 15:11

Exactly..

By GRoberts (***)

Date 09-28-2005 19:30

One option for you to aviod IGC without having to get costly specialized filler metal if your customer would accept it, is to use Nb containing filler metal, such as 347.

By - Date 09-28-2005 20:28

Mr. Roberts,
While I agree that a stabilized grade such as a 347 is certainly a deterent to IGA (sensitization), I very respectfully would not consider a 316L with with a C content of 0.025% or less a costly specialized filler metal. Just for an example, the Avesta 316L has a typical C content of 0.020%. It is quite normal for many SS consumables manufacturers to produce 316L in the 0.025% and less carbon range. Actually, a 347 is more costly than a 316L by approximately 15%. In stick electrodes, the cost is higher because of having to add the stabilizing agents into the flux. Solid wire (Mig, Tig, and SAW) is even slightly higher than the stick electrodes because of the amount of niobium added in relation to the C content in the wire mixture. If this fabricator is using a 308L for his 304L vessels and 316L for his 316L vessels, he will have to be welding WAY out of recommended parameters before he ever encounters sensitization, especially when fabricating vessels. By the way, I got this information on carbon content directly out of the Avesta filler metal actual certifications (not typical certs, but actual certs) and the prices of the 316L and the 347 directly out of our Customer Price Listings.

By GRoberts (***)

Date 09-30-2005 03:26

I was only responding to the original poster's comment that the price was canstantly rising. Most of the consumables I happen to purchase are FCAW, but if I remember correctly, the E347T0-1 is a dollar/lb or so more than 316LT0-1, but I don't recall what our typical C content on the 316LT0-1 is. I notice now that the original post also does not say what form of welding they will be doing, which of course can make a difference. I also couldn't tell where jiweiming is from. I imagine that in different parts of the world, pricing structures can be different.

By - Date 09-30-2005 12:33

I think Jimmy is trying to imply that the rise in cost is attributed to having to use lower carbon materials. Actually, the cost is less for a filler metal with low carbon (308L, 316L, 347 w/lower carbon) than these grades with higher carbon. If his costs are rising, I really don't think it's from having to use a L grade consumable. I say this because I know what "starter" steel costs before any alloys are put in, and I know the surcharges of the Cr, Mo, and Ni. Putting less alloys in a mixture does not make the cost go up, but less. It's like saying "I've been putting mid-range gas in my car, but now my manufacturer says to use a lower octane gas". Thus, a lower cost. If his costs are rising, it would be much more logical to assume that the cost is rising in the base metals rather than the filler metal. Jimmy also does not say what grade welding consumables he is using, only what grade the vessels are required to be made of. For that reason I assumed he would be using a 308L or a 316L or the 304L vessels, and a 316L for the 316L vessels. That is just an assumption. Regardless what welding process he is using, if he is using any of these grades, the L grade is less expensive to produce. Actually, the only 2 questions Jimmy asked was whether a lower corbon content was necessary to prevent IGA, and how do you prevent IGA. If he is "required", (his words, not mine) to build these vessels out of 304L and 316L and required to use a lower C content filler metal, then he has to be preared to incur whatever costs involved to fulfill these requirements. A requirement is not usually an option.

By jon20013 (*****)

Date 09-30-2005 12:56

Chuck, excellent response, as usual! It's not just the lower carbon that is driving prices upwards, I assure you (well, no need to assure you, Chuck, you know).

I don't know how many people are aware of this but several months back (heck, maybe nearly a year now) China bought up virtually all available scrap steels IN THE WORLD and, also placed orders on much of the available ore products, also on a world level.

Personally, since this happened, I've seen my own purchases of stainless jump from $7.90/lb to $17.80/lb since March of this year! Naturally, since I work in the nuclear industry, mechanical tests and chemistries are very controlled however, even on the commercial quality side prices have soared. This is the business side of things and has nothing to do with the technical side of the question.

Getting back to the posters original question of how to avoid intergranular corrosion better, while there may be a myriad of ways to improve this issue, one must still comply with Owner specifications. Having said that, all of the technical justification in the world would not help unless jiweiming's customer were willing to change their requirements.

As you astutely pointed out Chuck; a requirement is not usually an option.

By jon20013 (*****)

Date 09-30-2005 13:20

Incidentally, everyone in the USA can expect the costs of virtually ALL alloys materials to SKYROCKET as the Legal Beagles have found yet another topic for class action lawsuits... naturally, the Feds have also been convinced that the intake of certain metals into one's respiratory system is a bad thing, and I'm not saying it isn't, but people are going to die from something... whether it's chromium, fat from french fries or second hand tobacco smoke...

See below for an article I copied from a lawyers page:

An Illinois jury recently awarded $1 million to a welder who developed a Parkinson's-like disease called Manganism, from years of breathing manganese welding rod fumes.

In Larry Elam's case, the jury ruled that welding-rod manufacturers are responsible for failing to warn him about serious health risks. Elam, 65, of Collinsville, Ill., said he used rods made and sold by major companies across the country, including Lincoln Electric Co. in Cleveland. The companies argued that there is no link between welding and Parkinson's.

Attorneys for welders say workers suffered neurological damage from welding rod fumes that contain manganese, which stabilizes and hardens the weld. In documents, the attorneys said the fumes can lead to brain damage.

By definition, welding is the process of joining two metal parts by melting the parts at the joint and filling the space with molten metal. More than 500,000 men and women are employed in welding and welding related occupations in the United States. An estimated 200,000 welders are retired, creating a potential pool of 700,000 people who were exposed to manganese on a daily basis. "Of this pool of 700,000 welders, if 5-10% were potential victims of manganism or Parkinson's Disease then the potential pool of injured, disabled, impaired, ill people would be 35,000 human beings on the low end of the estimate and 70,000 humans, who have been wrongfully robbed of their health, at the high end of the estimate.

Studies have linked occupational exposure to welding fumes and manganese fumes to serious respiratory issues: pneumonitis, chronic obstructive respiratory disease; neurological diseases: manganism and Parkinson's Disease, and reproductive effects: lower sperm count and decreased testosterone levels.

The reason that welding rod fumes and manganese poisoning have caused such outrage is due to the fact that the harmful neurological effects of manganese have been widely known for more than a century. There are more than 80 different types of welding operations, including brazing, thermal cutting, and gauging, in commercial use. In welding and similar operations, such as brazing, thermal cutting, and gauging, the most frequently used method for generating heat is obtained either from an electric arc or a gas-oxygen flame.

The merging and combing of metals causes such intense heat that metals become ambient, airborne, entering the lungs and traveling in the blood stream to the brain. The welding fume is formed by the vaporization and recondensation of metallic elements upon cooling in ambient air. The amount of the emissions generated can vary substantially from process to process but the manganese is constant. The elemental composition of the fume varies with the electrode and work piece composition. Hazardous metals listed in the 1990 Clean Air Act Amendments that have been detected in welding fume include manganese, nickel, chromium, cobalt and lead. Additionally, the hexavalent form of chrome (Chrome +6) is also found in some welding fume emissions.

By - Date 09-30-2005 14:01

EXCELLENT information. One more thing to add...Since we are one of the two largest SS manfacturers of base metals and consumables in the world, we are one of the companies they are going after. I am familiar with this case you are referring to. The thing that also came out in this case is that the welding fumes is killing him. What also came out is that he smoked 2 packs of cigarettes a day. Mmmmm. wonder if that had anything to do with his lungs and neurological problems.

By jon20013 (*****)

Date 09-30-2005 14:30

It's sad, really, what our own legal system is doing to this country. What are we supposed to do, supply each welder with a self contained breathing apparatus during welding? Have manufacturers get completely fed up with trying to do business in America and move to some "third world country" where the government doesn't care anything about workers health as long as the almighty $$$ is rolling in?

If a person is alive and living outside of a purified oxygen environment, they are subject to some degree of risk. Has any of the legal beagles gone after the oil & gas industry for effects of industrial pollutants or automotive exhausts? As a 51 year old man who has lived a very full life and breathed more chromium and aluminum particulates that probably 95% of our population, I guess I have to ask when it will all end? I feel very sorry for our children and grandchildren for the things our system has done, or is doing to our country!

By - Date 09-30-2005 14:48

So true. I can virtually guarantee that there are more people who smoke than people that weld, yet the Gov't. makes cigarettes very readily available. It's just another way to give these ambulance chasing lawyers a way to screw the American public. Also, as having to have given depositions in this magnesium and chrome lawsuit, I can tell you that this is more subjective data than actual medical data concerning the amount of damage done by these alloys. Nothing like the proven medical data that cigarette smoke is more of a killer.

By jon20013 (*****)

Date 09-30-2005 15:45

Chuck, being a smoker myself, I can also guarentee that my bad habits will kill me long before any ingestion of chromium or other welding by-products will!

I'm not suggesting that being health conscious while welding is a bad thing, only suggesting there are a number of engineering controls which will mitigate the ingestion of these products. It sickens me to think that lawsuits are being filed in this matter, maybe we should just begin using crazy glue to build our products... oh yeah, crazy glue contains cyanide... maybe not such a good idea there either... Liquid weld maybe? Obviously dripping with sarcasm over our messed up legal system....

By GRoberts (***)

Date 09-30-2005 19:39

It looks like we are interpreting the original question a little differently. I thought the post was saying that the .025%C max material was more expensive than the .03% max material. I know for flux core, some manufacturers have problem staying below .03%, so depending on his process, I suppose it could be a factor. Whichever way he was asking about, he should have plenty of information now.
On a side note, I heard that Avesta was being bought by BTW. Is this true, or going to affect you?

By - Date 09-30-2005 20:09

I think we are interpreting it exactly the same. Like you, I interpret it as saying the 0.025% max is more expensive. I know for a fact that it is less expensive to produce a low carbon filler than a higher carbon. Virtually all manufacturers of SS filler metal produce the L grade in the range of 0.020 and 0.025% as standard practice. If he is paying more for it, then he needs to change distributors because he is getting took.
Yes, Avesta is being bought out by Bohler Thyssen. It will not affect me in any regard. Nor, will affect the rest of our personnel or our products. Absolutely nothing is going to change except our ownership. We will stay two totally different companies.

By GRoberts (***)

Date 10-04-2005 03:01

I would agree with you that manufacturing solid wire for GMAW or SAW with low carbon has been easy ever since the advent of AOD refining. However, for the FCAW or SMAW process, it seems like it would be more expensive to get low carbon because you have to use purer ingrediants for the coating/filling material. One manufacturer we buy a super-austenitic SMAW electrode from has difficulty meeting the .025% max carbon at times. Is that the case, or could it be the availability of low C core wire/strip that is more problematic?

By - Date 10-04-2005 12:04

We both agree that the SAW and GMAW is typically in the 0.020-0.025% of carbon for the L grades, right? For SMAW, as we spoke of, the core wire is normally regular 304 material with a low carbon content usually no more that 0.025%. I'm not sure what you mean by saying purer ingredients are required for a low carbon coating on the SMAW electrode. The chemistry is the same except for the lower carbon content. The lower amount of alloying agent that is used lowers the cost of production slightly, depending what alloy agent you are lowering. The core wire is produced the same way the SAW and GMAW and GTAW wire is produced. Even with the super austenitic SMAW electrodes, I cannot fathom why it is a problem meeting the 0.025% C and lower. The Avesta 904L and 625 electrodes (super austenitics) have a typical carbon content of 0.020%. Virtually all of the super austenitics I've ever worked with have the C content on the lower range. Maybe you should switch to the Avesta brand. ;-)

By jiweiming (**)

Date 09-29-2005 03:30

If 347 welding consumables used,does it need to carry out atablization PWHT?

By - Date 09-29-2005 10:06

Generally, a stabilization PWHT is done when welding 347 stainless steel while using a 347 filler metal. As is usual in stainless steel welding, the most recommended PWHT is a solution annealing process with the temperature reaching around at least 1000C, or 1850F. A stabilization PWHT can be considered a part of the solution annealing process. The purpose of a solution anneal is to dissolve carbides. To assure free carbon resulting from the dissolution of these carbides reciprocate as niobium carbides, it is often desirable to arrest the cooling cycle in the range of 900-1000C (1650-1850F). Stabilization heat treatments, when done when welding 347 stainless steels, are especially needed in the narrow region of the HAZ where all the carbides have dissolved that may cause IGA in a form called "knife line attack". Too long a time at this lower end temperature can run the risk of embrittlement due to sigma formation. For most applications, including welding a 316L while using a 347 filler metal, this stabilization PWHT is deemed unnecessary. As it has been pointed out to you in previous threads, when fabricating constructions using a 304L or 316L stainless steel, these grades normally, using proper welding procedures, will slow down the rate of carbide precipitation so that sensitization is not an issue. If you are unsure whether your welders can comply with proper welding procedures that will prevent the onset of sensitization, then maybe you should consider using a stabilized grade of stainless steel like a 321 or 347. Otherwise, you should have no problems preventing sensitization using a 316L filler metal when welding your 316L vessel.