Low Mo content in ASTM 4140 1

[LBW87]

What would be the consequence of a low Molybdenum content in ASTM 4140, say around 0.01-0.02%? I'm using the steel in the B7 condition in a tensile application.
Thanks for your help.

 

[metengr]

LBW87;
What, 0.01 to 0.02% in total mass of Mo in the steel or below the specified minimum of 0.15%? This is not 4140, if what you report is the mass percent of Mo. Check your numbers again.

 

[dbooker630]

It would not be 4140 at .01-.02% Mo; more like 5140.

 

[CoryPad]

The consequence is reduced hardenability. You need to check the mechanical properties of your parts.

Regards,

Cory

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

 

[LBW87]

The mechanical properties on three samples tested are good with the exception that the elongation of one sample was under spec at 13.5% vs 16% and each sample was a bit soft at 28 HRC.

 

[metengr]

The tensile results will be influenced primarily by carbon content not molybdenum. Molybdenum, influences hardenability, as mentioned by CoryPad, and elevated temperature strength. I would re-check the chemical composition results, and if it is not 4140 either send it back or use as is knowing it is not 4140. You mentioned B7 in your OP, is this supposed to be A 193 Grade B7 material?

 

[LBW87]

Thank you metengr. Yes it is supposed to be A 193 Grade B7.

 

[metengr]

LBW87;
As I thought. You better re-evaluate the use of this for stud material because low Mo is unacceptable. The B7 stud material is suited for moderate to elevated temperature service (up to 800 deg F), and if you have low Mo this would be unacceptable to me for service.