Nickel Percentage and Welding AISI 202

nbhide108,

It has been some time since I have cracked the books in regards to metallurgical properties dealing with the various grades of stainless steel. The following information may not be 100 percent accurate, and I suggest you perform some further research, or be open to other responses from others who have more relevant up to date knowledge on the subject.

1) I believe the absence of Ni in stainless manufactured to AISI 202 specifications is meaningless because a lack of Ni would make that steel non-conforming to the 202 specifications.

2) The significance of Ni in stainless steel........The higher the Ni (nickel) content in most cases will mean better resistance to corrosion and oxidation. When welding stainless steels that conform to AISI 202 and other AISI specifications, the Ni content has a direct effect on the weld quality. If I recall correctly, some stainless steel compositions that have a very small Ni content, are more ferritic and will exhibit brittle metal at or near the weld joint compared to stainless with a greater Ni content. This could be problematic for products that are susceptible to expansion/contraction or vibration.

As I stated earlier, it has been a while since I have researched much of anything to do with stainless steel properties, and I hope if I have led you down the wrong path someone with more familiarity on the subject will give you the correct information you are seeking..........good luck with your research.

Chrome is the primary anti-corrosion additive in stainless when exposed to "the elements". However, chrome is hard to the point of brittle and lends these properties to the steel it is alloyed with.

Nickel is less corrosion resistant when exposed to "the elements", but is ductile and tough. It too lends these properties to the parent steel.

So to get a material that can be practically worked and welded while having enhanced corrosion resistance, both elements are present in most grades (types) of stainless. The amounts of either are varied to achieve specific properties, and / or alloy with other elements.

If you decide to pursue further study of stainless materials, you'll find that it is a world unto itself.

The element it's called "chromium". Chrome is what hillbillies lay on their truck mufflers... With the rest, I agree.

Titi-the-rabbit.

The best source for Nickel information that I know of is the Nickel Development Institute (NIDI). This group is made up of the some of the most experienced people in the industry who have spent most of their lives working with nickel. There is also a good stainless steel at McKay's website. They provide a world of information about all stainless, even the 400 series and Duplex.

Here is a link to a useful table that compares chemical + physical properties of 304, 430 + 410 series Stainless Steel: http://www.ssina.com/composition/chemical.html

Information on 200 series can also be found on the Stainless Steel Information Center website; it has links to a wealth of information on specs, grades, classifications and fabrication, including welding.

Query: this is a 30 second lookup via Google - why didn't you do that first?

the 200 series has been developed as a cheaper alternative to the SS 300 series (304 & 316). the 200 has a lower nickel vs the 300 series and an higher content of Mn. the corrosion resistance is more or less the same .

http://www.bssa.org.uk/cms/File/200seriesbssa.pdf

Nickel prices have been relatively high over the last couple of years. As a result, there has been increased interest in low-nickel or no-nickel grades of stainless steel.

One such family of stainless steels is the 200-series and use of these has doubled this decade. They have become popular in China and South East Asia, particularly. However, this has not been without problems.

Because the 200-series grades are austenitic, they are not magnetic and are therefore very difficult to distinguish from the widely used 300-series grades, such as 304 or 316, which are also non-magnetic. This has led to confusion in the marketplace, including cases of incorrect labeling, etc, with 200-series material being sold as 304.

Most growth in 200-series use over recent years has been in low-nickel and therefore low-chromium versions which have less corrosion resistance than 304. The end result has been corrosion failures in some applications and dissatisfied customers. In addition, there are concerns that this 200-series material may contaminate the existing stainless steel recycling circuit which is based on 304.

The 200-series is a technically valid family of stainless steels but, like all stainless steel grades, they have their limitations. If you are considering the use of a 200-series material then you should ensure you have all the necessary data you require to make a rational judgment - mechanical and physical properties, corrosion performance in your environment, etc. And it is strongly recommended that you deal only with reputable and knowledgeable suppliers who can provide high quality material of known origin."

http://www.assda.asn.au/index.php?Itemid=89&id=63&option=com_content&task=view

rust & corrosion protection

This has been a most informative forum. One of the best I have experienced on this web site. Most of the comments were positive and helpful. I didn't like the one about the element being Chromium and not Chrome like a Hillbilly puts on the exhaust system. I am a hillbilly and we define Chrome as something that the shop refers to as Chrome and the people in the engineering call Chromium. If we are working on a Cr Mo job, we all refer to it as Chrome Moly.

This web site is beneficial even to an old guy who has been involved with Metallurgy and Welding for nearly 50 years. I learn something from it everyday! Thanks to all you guys and gals!

This is the site that i have been searching for a while.

you guys are posting great info. keep it up!

I got a Chrome moly mongoose when i was a kid... best Christmas ever!

I also use straight nickel rod when tig welding iron. it has enough ductility to keep the weld from cracking. brazing with brass is more fun though!