4130 properties 1

[degins]

I am working with a casting that requires yield strength of ~850 mpa with elongation >16%. I suggested that the foundry use 4130-4140 alloy. They used an alloy like 4130, but with elevated Mn and with a small amount of Ni. Please see chart.

I would appreciate if anyone could share their experience with me and advise me as to what is the general effect of adding small amounts of Ni or elevated Mn to this or other low alloy steels.

C: 0.32
Mn: 1.15
Mo: 0.18
Si: 0.41
Cr: 0.66
Ni: 0.41

My application is for automotive steering components. Thank you for any advise.

 

[metengr]

The problem that I see has nothing to do with what the foundry supplied. It has more to do with you not having specified a cast 4140 alloy steel in accordance with a Standard Specification, like ASTM A 915 titled 'Steel Castings, Carbon, and Alloy, Chemical Requirements Similar to Standard Wrought Grades" .The actual grade is J14045, per this Specification. Being in the automotive business what about SAE Casting Specifications? What about quality level for the castings?

As a minimum, I would suggest you download a copy of the Steel Castings Handbook Supplement 2, 1999 Edition. Look thru this Supplement and determine if one of the recommended ASTM Specifications fits your application. By ordering to this ASTM or possibly an SAE specification, in addition to chemical composition, heat treatment of the material is specified.

Getting back to your question, if it was me and this is for an automotive steering component, I would send the cast material back and re-order the castings to a proper Standard.

 

[degins]

"metengr (Materials) 29 Jul 05 22:12
The problem that I see has nothing to do with what the foundry supplied. It has more to do with you not having specified a cast 4140 alloy steel in accordance with a Standard Specification, like ASTM A 915 titled 'Steel Castings, Carbon, and Alloy, Chemical Requirements Similar to Standard Wrought Grades" .The actual grade is J14045, per this Specification. Being in the automotive business what about SAE Casting Specifications? What about quality level for the castings?....

Thank you for the response. Indeed, the specifications indicate chemical compositions and heat treatments which will result in a given mechanical property. This is useful, but my query relates to the metallurgical effect of the stated elements. Do these elements (Mn, Ni) inpart unique properties/drawbacks, what are these unique properties/drawbacks.

 

[metengr]

degins;
Ok, having understood my response, I can provide some comments regarding the affects of Mn and Ni. I just wanted to make sure that accepting a heat of material with no original specification can be a serious problem.

For Mn; this alloy addition is essential because it is a deoxidizer and desulfurizer during steel production. Mn is a strengthener and increases the hardness of steel, and is very effective in increasing hardenability. However, too much Mn in a steel can increase sensitivity to temper embrittlement (loss of toughness, ductility) along with chromium. Typically, a 3:1 ratio of Mn:C is common for steel production.

For Ni, this alloy addition increases strength and response to heat treatment to a lesser extent than Mn. However, most importantly, it increases the toughness of the steel. Considering the level of Ni you have in this heat, I would expect it to behave as more of a tramp element. You would need to increase the Ni content to about 1.5% or higher to really see the benefits.