Help determining stainless material from lab results 3

[nickjk]

I am trying to determine the material of a detail I had tested at a local laboratory.
Prior to testing I believed the material to be a hardened 440C stainless steel.
Results from the lab stated that the core hardeness was Rockwell HRC 61
Chemical Analysis show the elements to be.
C .98 Ni .09
S <.005 Mo 1.88
P .024 V .17
Si .94 Al .01
Mn .50 Cu .11
Cr 8.39 Ti .006
Co .016
The average prior austenitic grain size was estimated to be 10.0 in the section examined.
The lab said they did a search in their data base, ASTM and SAE specifications with no material matches.
I do not understand, I have never seen a stainless steel that can be hardened to the stated Rockwell that has such a low chromium level.
Any help trying to determine what this material may be would greatly be appreciated.
Thanks in advance,
Nickjk

 

[cloa]

Looks like a martensitic medium alloy steel. Don't confuse hardenability with maximum achiveable hardness- the former is how far along a standard bar which is heated to austenite can get hard (which mostly a function of alloy elements and grain size most strongly non-carbon elements) and achievable hardness the hardness at the end of that bar (strongest effect is carbon content).

Its definitely not a stainless steel (min Cr 12%).


Using

http://www.amerpipe.com/reference/charts-calculators/carbon-equivalent

CE= 3.1646666666666667

http://www.leonghuat.com/articles/carbon equivalent.htm

 

[nickjk]

Thank you for your response and the link with the carbon equivalent calculator.

The only reason I stated hardness and chromium level was because the component is used in a hydraulic environment without coating I truly believe it is made from some form of stainless steel to prevent corrosion. From my research there are very few stainless materials capable of heat treat to 60 Rock "C" and none of them had chromium content that high.

The analysis method used was ASTM E1019-08, Bulk chemical analysis by glow discharge.

Is it possible that the lab made a mistake on the element percentage?

This is my first time using a lab to determine a material and I am not sure I have confidence in the test results.

Any help would greatly be appreciated.

Nickjk

 

[metengr]

Is it possible that the lab made a mistake on the element percentage?

Highly unlikely. You as the customer can request them to re-check the quantative analysis.

 

[cloa]

According to what you wrote Cr=8.39, surely you mean a "stainless steel" with chromium content that low (as I said that is not a stainless steel).

 

[nickjk]

Cloa you are correct.

And I agree, if the chromium value is correct it cannot be stainless.

Could anyone give me suggestions on what they feel would be the best approach to try and determine what the material it is?

Were to start and look?

Any help would truly be appreciated.

Thank you,

Nickjk

 

[metengr]

Have the lab run a wet chemical analysis.

 

[TVP]

nickjk,

ASTM E1019 cannot be used to determine the chromium content in a steel sample. Read the abstract of ASTM E1019 here:

http://www.astm.org/Standards/E1019.htm

You should discuss the details of this with the lab, including what is the exact method that they used, the relevant ASTM standard, and whether or not they have the appropriate calibration and accreditation for the specific method/standard. Cr detection in a martensitic stainless steel is different than Cr detection in a low alloy steel, and may require a wet chemical method (ICP or other) if the lab in question is not familiar with testing low-Cr stainless steels like Type 440.

 

[EdStainless]

Could pass for a tool steel, a hot die grade, I don't have my tables handy to look it up.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[nickjk]

I asked the lab if they have ever seen a material similar in make up. The response was not here in the states but yes in items tested from Japan.

After looking at hot worked tool steel tables I do not believe it to be a tool steel, but thanks for the thought.

My application is similar to a static loaded ball bearing race.
Corrosion resistance is important.
I am planning on using 440C stainless to move forward.

Thanks for everyones help

Nickjk

 

[EdStainless]

OK, let me rephrase that.
This is not a stainless, the Cr is too low to start and with that much C it will have even less Cr in the matrix after the carbides are formed.
This alloy may harden better than 440C with the balance (Mo and V added) and should end up with just as good of corrosion resistance.
It is a tool steel.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[nickjk]

Ed,

Sorry, I thought it was not a tool steel only because the Cr values of the tool steels I looked up were around 5.5%, maybe I missed something. I also know from the Cr value it is not a stainless material. Do you have a tool steel in mind with similar percentages, I could not find one.

Thank you,

Nickjk

 

[TVP]

As a group, they are often referred to as 8% Cr tool steels. Most tool steel producers have their own proprietary/patented grade. Here are a few examples:

Daido DC53

http://www.imsteel.com/cold_work_die_steels/dc53/dc53_home.htm

BÖHLER K340

http://www.bohler-edelstahl.com/english/3382_ENG_HTML.php

Hitachi SLD8

http://www.hitachimetals.com/product/specialtysteel/toolsteel/doc/YSS_cold_working_die.pdf

Uddeholm Sleipner

http://www.bucanada.ca/sleipner_c.htm