Replacement of 6150 with 52100 2

[perilous]

Hey there. We've got a straightener roll that shall be made from 6150 steel. As the required stock isn't available for now in local market, we've considered changing it to 52100. As you may see in the attached drawing the drum ought to be hardened and tempered to be as strong as at least 1000 MPa. I've checked it up in resources (German Stahlschlüssel, etc.) to know the tempering temperature needed to have a 52100 with that much strength but, I guess because of the application of 52100 (bearing steel) they don't mention as-tempered properties for temperatures above 200 °C nor the mechanical properties at all! How can I get to know about it except doing a tensile test?

 

I would not accept that substitution (is a supplier offering this?). 52100 is a bearing steel, 6150 is shaft alloy.
I think 4140/4150 should give reasonable overlap with composition and the required mechanical properties.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

The other issue is that the high strength is only needed on the barrel, the core and end shafts need to be a bit softer and much tougher.
Likewise I would stick with a 50 C steel.

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P.E. Metallurgy, Plymouth Tube

 

[perilous]

@ironic_metallurgist
4140/4150 that's exactly what's been suggested (not by the supplier but the contractor who's in charge of making the roll) won't give the required hardness after induction. According to my experience the maximum achievable hardness would be 45 HRC (we need 62-65 HRC).

@EdStainless
They say it takes 4-5 months to produce 50Cr of this diameter with minimum order quantity of 15 tons! So wouldn't a 52100 tempered with higher degrees (>400) help? How much would it be the strength of a 52100 with hardness of e.g. 27 HRC?

 

[AidanMc]

62-65 HRC is tool steel territory. Maybe something like A2 or O1?

I'll admit that I don't have any experience with induction hardening though so I'm not sure if they'll react differently with that.

 

perilous,
Maximum achievable hardness in steel is governed by the carbon content, so your substitute steel will be called xx50 (or something close to 50).
Alloy content (the xx component of previous) determines the depth of hardening. For that you refer to hardenability curves developed from Jominy end-quench testing.
Whatever you choose it appears some development work will be necessary to validate the selection.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

How about 5160? It should harden over 60HRC.
I don't know what numbers you are using for 4150, but the hardenability data that I have show max as quenched hardness in the low 60's also.
4140 will reach a max as quenched hardness of 55+HRC without any trouble.

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P.E. Metallurgy, Plymouth Tube

 

[WKTaylor]

OK, someone...

HT = 1000-Mpa = ~145-KSI
Dia of the section = ~305mm = ~12.00-inch

MMPDS-12...
Table 2.3.0.2. Maximum Round Diameters for Low-Alloy Steel Bars (Through
Hardening to at Least 90 Percent Martensite at Center)
Figure 2.3.0.2. Correlation between significant dimensions of common shapes
other than round and the diameters of round bars. MIL-H-6875 has been cancelled and
replaced by AMS-H-6875A

Isn't this section excessively deep for thru hardening, any 'typical' LA steel to the strength level listed?

Aerospace perspective, ideas...

What about 9Ni-4Co-.3C or -.4C high-temp resistant deep-section-hardening steel forging with 'flash-chrome' or other suitable wear finish?

or...

CREN bearing steel [nitrogen surface hardenable] forging?



Regards, Wil Taylor

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[EdStainless]

WKT, Correct, none of these alloy would through harden.
But 145ksi is well below max hardness for a 50C alloy, you should be able to reach that even in heavy sections.
And then surface harden the enter section of the roll.

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P.E. Metallurgy, Plymouth Tube