joubjonn
Well-known member
found this, seems helpful
http://nanolab.berkeley.edu/labmanual/chap1/1.10miscetch.pdf
http://nanolab.berkeley.edu/labmanual/chap1/1.10miscetch.pdf
Etchant's List
- Thread starter joubjonn
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joubjonn
Well-known member
I will say. This list mentions HF frequently. I won't even spell it out. I know we don't condone the use of that for refining as it really has no good use for us for all our processes. So anyone new reading the list and seeing that keep in mind it is a list made for UC Berkley, where they have lab coat's and fume hoods. Don't use HF, don't buy it, don't even worry about it. You don't need it. I remember in college my professors mentioning it, and how extremely dangerous it is.
Wow this is great!
I am by trade a metallurgical engineer and have done my real world training along side my father a very well respected super alloy metallurgist. We use Nital for basic low alloy steel cast iron etc. but when you get into super alloys especially those high in nickel, cobalt or other more exotic materials etching becomes an art. Cobalt that has been electrolytically etched looks beautiful colors are amazing.
There are times when we require a specific etchant based on the alloy chem. and always have to dig through our extensive research library to find the proper one this might help with that in some cases.
Very cool!
I am by trade a metallurgical engineer and have done my real world training along side my father a very well respected super alloy metallurgist. We use Nital for basic low alloy steel cast iron etc. but when you get into super alloys especially those high in nickel, cobalt or other more exotic materials etching becomes an art. Cobalt that has been electrolytically etched looks beautiful colors are amazing.
There are times when we require a specific etchant based on the alloy chem. and always have to dig through our extensive research library to find the proper one this might help with that in some cases.
Very cool!
Also I noticed they listed both colombium and niobium I hope they are aware they are the same element just with different names depending upon where you live. I believe the British used one term and we (USA) used another and they both stuck I haven't seen a perodic table with colombium listed always Nb. The limeys have always done things like this to the metallurgical world. Most people don't realize that UK's 300 series stainless (austenitic) steel used cobalt instead of nickel for the first 40 - 50 years because their African colonies had abundant supplies and it was cheaper for them to use Co rather than Ni. We get this question a lot about cobalt values affecting the behavior of 300 series. In case you wondered 304 (18-8) for example has a 8 Ni MAX but a 4 Ni & 4 Co is acceptable as long as the Co + Ni levels do not exceed the maximum required Ni levels all is good. Cobalt is beneficial in some cases (but rarely used) good corrosion resistance as well as superior high temperature properties.
joubjonn
Well-known member
Good info. I deal a lot with alloys in oil and gas. We pretty much use 13Cr mostly with 25Cr, 718, S13Cr and sometimes 4140 but we try and stay away from it. As well as many different carbide grades. It does get interesting when dealing with high H2S wells or wells with C02 figuring out what the best material is. I have this interesting failure we are trying to figure out right now. 13Cr with a press fit ID carbide nose. The 13Cr cracked on the OD where the carbide was press fit. I have never seen 13Cr crack before. I keep thinking it was an interference fit issue and maybe temperature played a role. The tool never went down hole but was shipped to Brazil and function tested (it's a hydraulic sliding sleeve) they found the crack during the test. Ever seen anything like that?
goldenchild
Well-known member
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- Aug 14, 2009
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joubjonn said:
I would also add piranha to this although I don't think it's as dangerous as HF.
At one place I worked, I did a lot of sectioning, grinding, mounting, and polishing of plated samples (mounted on edge), mainly for plating thickness measurements on a high-power metallograph with built-in measuring scales. After the final polishing, I used many of those etchants to enhance and distinguish between the various plated layers. The etchants used were, of course, dependent on the metals involved. On soft metals, such as gold, outward smearing into the softer mounting plastic could easily occur during polishing and this would give high answers. To combat this, I plated a layer of a hard metal, such as nickel, over the gold before sectioning. The etchant list you gave brought back memories. I enjoyed doing it.
joubjonn said:
I never have really done much work with 13Cr alloy as we deal with mainly cast grade alloys but not limited to by any means. The carbide nose is press fit and the cracking is occurring where the carbide attachment is being fit? If I am correct with my understanding it sounds like a stress/fatigue crack/fracture from the pressure of the press when the carbide is attached. Have you checked alloy chemistry to see if there are any variations between the parts that have cracked and the parts that are not cracking? What is the condition of the 13Cr material, annealed or heat treated? If this is a constant problem in which money is being lost perhaps think about an alloy swap. 13Cr is readily used in the environments you mentioned but there are alloys with better performance characteristics that would have the same if not better corrosion resistance. Of course $ becomes an issue. This is just a 2 minute response if you want to post some pics or just send me some I can get a better idea of what you are working with.
joubjonn
Well-known member
I remember this. We never figured it out. Never happened again. Oil field mystery 10 years later I run the product line. Funny reading my old posts.
