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Carburizing Stainless Steel
- Thread starter Lcubed
- Start date
If you carburize a stainless steel it will no longer will be stainless at the outer surface. Stainless steel are usually nitrided. This too will reduce the corrosion resistance ability of the stainless steel but not as much as adding carbon.
LCubed, I'd like to know what bought up the possibility that it may be stainless. Bit of a leap to go from surface hardness to material identification without other info. How did you determine that the spline is carburised?
LewTam Inc.
Petrophysicist, Head Stockman, Gun Welder, Gun Shearer, Ski Instructor, Drama Coach.
LewTam Inc.
Petrophysicist, Head Stockman, Gun Welder, Gun Shearer, Ski Instructor, Drama Coach.
- Thread starter
- #5
lewtam-
The drawing calls out the carburization, but not the material spec. We are thinking about trying a little reverse engineering, and I thought that if SS cannot be carburized, our shaft must not be stainless. Incidentally, the shaft is slightly magnetic. This is not really critical, because there is no reason to make the part from stainless, but we are curious. Being structural, and not a metallurgist, I just wanted to inquire and learn what I could.
CoryPad and Israelkk-
Thank you for the leads.
I appreciate your help and advice.
Regards,
Lcubed
The drawing calls out the carburization, but not the material spec. We are thinking about trying a little reverse engineering, and I thought that if SS cannot be carburized, our shaft must not be stainless. Incidentally, the shaft is slightly magnetic. This is not really critical, because there is no reason to make the part from stainless, but we are curious. Being structural, and not a metallurgist, I just wanted to inquire and learn what I could.
CoryPad and Israelkk-
Thank you for the leads.
I appreciate your help and advice.
Regards,
Lcubed
diamondjim
Mechanical
Not likely to be stainless steel.
possibly 1050, 4140, 4150, 8660
or
4023, 5120, 4118, 8620, and 4620
or
4320, 4817, and 9310
possibly 1050, 4140, 4150, 8660
or
4023, 5120, 4118, 8620, and 4620
or
4320, 4817, and 9310
diamondjim- Lcubed mentions slightly magnetic. That confuses me, do you mean A) slightly attracts metal objects? or B) is only slightly attracted to a magnet?
if A, then it could be regular steel as diamondjim states, if B, I am at a loss as to how high of a hardness you've got along with lack of ferro-magnetism.
if A, then it could be regular steel as diamondjim states, if B, I am at a loss as to how high of a hardness you've got along with lack of ferro-magnetism.
- Thread starter
- #8
This is for carburize and IsraelKK-
If this shaft was made of a non-magnetic SS (IE 304) and the surface was carburized to get hardness as great or greater than common martensitic (420 or 440) stainlesses. Then would the case behave like the martensitic grades? and would the shaft then have the magnetic properties that Lcubed described?
I just dont see how steel will have a HRc of 58 while remaining non-magnetic.
If this shaft was made of a non-magnetic SS (IE 304) and the surface was carburized to get hardness as great or greater than common martensitic (420 or 440) stainlesses. Then would the case behave like the martensitic grades? and would the shaft then have the magnetic properties that Lcubed described?
I just dont see how steel will have a HRc of 58 while remaining non-magnetic.
SMF1964;
I believe the maraging steels are magnetic. The relatively low carbon Fe-Ni martensite forms after solution annealing. This allows forming operations and upon subsequent aging, precipitates form in the martensite resulting in excellent toughness and strength. Magnetic properties do change with aging.
I believe the maraging steels are magnetic. The relatively low carbon Fe-Ni martensite forms after solution annealing. This allows forming operations and upon subsequent aging, precipitates form in the martensite resulting in excellent toughness and strength. Magnetic properties do change with aging.
NickE - Sorry for the delay - just got back from a visit to Europe -Carbon is an austenite stabilizer, so increasing the surface carbon content on a material like 304 would just make it more likely to behave as a fully austenitic material with lower ferro-magnetism.
EdStainless
Materials
There are some systems to put C and N into stainless at low enough temp that you get almost no carbide formation, just intersitial strengthening. You would never get anywhere near this hardness with that though.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
Take a look at this process.
A couple of other possibilities. I assume the shaft is made of cold drawn barstock. If it is austenitic stainless steel, the cold deformation could induce enough transformation to martensite to give the slight magnetic response noted. Also, some of the austenitic stainlesses on the market now are so lean in nickel (due to the price of Ni) that they contain some magnetic ferrite phase.
With respect to carburization, the "traditional" carburizing processes that have been applied to stainless steel significantly reduce the corrosion resistance due to chromium precipitation with the carbon. But there have been a few new processes developed that are performed at temperatures low enough that the chromium does not diffuse to form the carbides. Kolsterizing is an example. These processes are generally applicable only to austenitic stainlesses. The carbon occupies interstitial sites in the austenite FCC lattice structure. The result is corrosion resistance at least equivalent to the unhardened alloy, superior SCC and fatigue resistance (due to the high residual compressive stress state in the hardened case), and hardness in the range about 70 Rc.
I am familiar with the Kolsterizing process, as we have used it for over 15 years with great success. Details of the process are confidential, however.
With respect to carburization, the "traditional" carburizing processes that have been applied to stainless steel significantly reduce the corrosion resistance due to chromium precipitation with the carbon. But there have been a few new processes developed that are performed at temperatures low enough that the chromium does not diffuse to form the carbides. Kolsterizing is an example. These processes are generally applicable only to austenitic stainlesses. The carbon occupies interstitial sites in the austenite FCC lattice structure. The result is corrosion resistance at least equivalent to the unhardened alloy, superior SCC and fatigue resistance (due to the high residual compressive stress state in the hardened case), and hardness in the range about 70 Rc.
I am familiar with the Kolsterizing process, as we have used it for over 15 years with great success. Details of the process are confidential, however.
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