Delayed cracking of 200 series stainless steel

[SteveyG]

all this talk of saucepans made me wonder if anyone had any information on the delayed cracking of 200 series stainless steel.
this is something that can happen to 200 series deep drawn cookware (usually but not exclusively the 1% nickel grades rather than the traditional AISI 201/202 types)

i found the following -

“New 200-series” steels:
An opportunity or a threat to the image of
stainless steel?"

and

THE NEW 200-SERIES : AN ALTERNATIVE ANSWER TO NI. SURCHARGE ?
DREAM OR NIGHTMARE?

I need to know a lot more about this effect - i tend to assume delayed cracking is a mechanism akin to SCC ??

I will probably be 'pestering' the steelmakers and see if i can find other sources, but if anyone can help at all I would certainly be most grateful.



Materials technologist/metallurgist

 

[EdStainless]

There are some 200 grades that form a lot of transformation martinsite when it is heavily deformed. These alloys could crack from a number of different mechanisms.
If the material is stable enough to stay non-magnetic then the cracking must be from CSCC.

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Plymouth Tube

 

[mcguire]

There isn't much published on this topic, but I can tell you that austenitic stainless steels behave very similarly whether the austenite is stabilized by manganese or nickel. Once pitting corrosion conditions exist, SCC failure may ensue depending on stress and temperature.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[EdStainless]

I was leading to the fact that some 200 alloys for huge amounts of martensite and are susceptible to cracking from this.

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Plymouth Tube

 

[mcguire]

Right, Ed. The leaner 200 alloys form martensite from deformation in forming leading to delayed hydrogen cracking, the same as 301. And if these alloys are annealed in hydrogen, they must sit and out-gas before severe forming.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[TVP]

SteveyG,

Delayed fracture of metastable austenitic stainless steels due to hydrogen interaction with deformation-induced martensite has been documented in some journal articles, etc. Here is a very recent one:

Hydrogen-induced delayed cracking in the AISI 301 unstable austenitic steel sheet

http://www.sciencedirect.com/science/article/pii/S0261306910001585

Here is a Google Scholar search. I used "delayed fracture" as a keyword, but there will be more hits using hydrogen embrittlement:

http://scholar.google.com/scholar?a...s_sdt=1.&as_sdtp=on&as_sdtf=&as_sdts=23&hl=en

 

[SteveyG]

thx guys

how dumb am I, I never even heard of Google Scholar !

""There isn't much published on this topic, but I can tell you that austenitic stainless steels behave very similarly whether the austenite is stabilized by manganese or nickel.""

but the 1% nickel grades are the more prone to cracking, regardless of the amount of manganese content to stabilize? and the 4% Ni grades are far less prone but more prone than 18/8.
(although that seems debatable - the doc attached i just found has a 4% nickel grade with same risk of delayed cracking s 18/8, although it does have copper to lower work hardening rate)
so is there not a relationship between the nickel content and the risk of delayed cracking/cold cracking?

it appears there is a limit to the amount of manganese or nitrogen content to stabilize and there should always be at least some nickel content?

i will need to do a bit of studying but not for 2 weeks, I'll be on a beach in Turkey soon....






Materials technologist/metallurgist

 

[EdStainless]

Austenite stabalizers, Ni, C, N, Mn, Cu, Co .....
A 200 with 1% Ni, enough Mn, and a boat load of C (0.08%) and N (0.25%) will be stable when cold worked, and it would reach real high strength.
I have never seen a 200 that didn't form a lot of martensite on cold work. They really are metasable alloys.

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