material strength of case hardened low carbon steel

[limct]

Can anyone advise if there's a method (other than the destructive test) to find out the difference of the material strength of a case nardened low carbon steel shaft as compare to a non heat treated one.

 

[TVP]

Electromagnetic methods (eddy-current) can be used for discrimating the case depth (or lack of case depth) in surface hardened components. I am not sure how quantitative the method is for determining hardness values vs. just identifying hardness depth. Try the following sites for more information:

http://www.cnde.iastate.edu/cnde_news/e-newsletter0201/PDF files/Eddy Current Measurements.pdf

http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=eddy+current+case+depth

 

[CoryPad]

What is your definition of material strength? Do you want to know the tension stress to break the shaft, the torsional stress to break the shaft, the contact pressure required to indent the shaft, or something else? The case properties are localized to the area near the surface. If you are concerned with surface properties, then the case can have a large influence. If you are concerned about bulk properties, then the case has a much smaller influence.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[limct]

Hi TVP,
Thanks for the advise, But I think my earlier was a hasty one, I should have elaborated more specifically that the material strength that I mentioned was actually the allowable bending moment / tensile strength for case gardened shaft and the non hardened one.

 

[limct]

Hi Corypad,
I'm considering the bulk property, so if there's an influenze between the case hardened and an non-hardened one, should there any methodology to quantify that?

 

[TVP]

Standards such as DIN 50150 and SAE J419 give approximations of tensile strength for a given hardness value. I believe this data appears in other places like Machinery's Handbook. You can then use an estimate that the yield strength is equal to 90% of the tensile strength for tempered martensitic steels. Plug this value into the maximum bending moment equation to determine the onset of yielding.

 

[unclesyd]

I some data for different carburizing grades of both carbon and alloy steel. The data is for both a carburized and a mock carburized grade. The heat treatment after the carburizing determine how tough the material is to a great degree.
If you data on any these old steels come back with a number.
1015
1020
1022
1117
1118
or
3310
4320
4620
4820
8620
9310

 

[limct]

Hi unclesyd,
I need to have comparison between.
C12L14 free cutting steel
1022 low carbon steel
SCr415 Chromium alloy steel
SCM415 Chrome Molydenium alloy steel

Thanks.

 

[CoryPad]

limct,

To what depth are these steels carburized? What is the ratio of sectional areas for the carburized and non-carburized areas?

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[unclesyd]

limct,
I only have information on the steels I listed. Maybe CoryPad or someone might have access to a SAE Handbook or the Japanese equivalent. The SAE & Bethlehem Steel is where my data is form. I don’t have anything approaching the low carbons of the SCr415 or the SCM 415.


T.S Y.P. El Rd Izod
1022 (as rolled) 72K 52K 35 67 60
(annealed) 63.3K 46K 35 64 89
(Carb.. ) 82K 47K 27 66 81
(Mock Car) 87K 37K 26 57 70