Ductility of Investment cast 4140? 1

[Ian63]

I have recently received some 4140 investment cast sample parts from our Chinese supplier, and although they looked good, failed in a very brittle manner. Investigation revealed that the parts we in fact not heat treated.

I am about to test them again after a proper quench and temper to achieve 35 HRc by a local quality heat treatment firm. What I am wondering though is given it is investment cast, how ductile or tough will it be compared to parts that have been machined or milled from bar or billet?

Ian.

eng-tips, by professional engineers for professional engineers

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

 

[jwhit]

You can probably expect somewhere around 7% Elongation minimum and 12% Reduction of Area on this material. I won't venture a guess on notch toughness since Chinese material can be pretty much mystery metal when it comes to what, besides the specified elements is in there.

 

[EdStainless]

Look up the cast steel spec and see what the min values are.
This should be J14045 in ASTM A915 (I think).

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

 

[mrfailure]

The casting grade in A915 is SC 4140 (UNS J14045 as Ed correctly remembered). Heat treatment of this grade is required, but A915 does not include tensile or mechanical requirements, leaving them to be supplemental between supplier and purchaser.

Aaron Tanzer

http://www.lehightesting.com

 

[metengr]

Look at ASTM A 958 Standard Specification for
Steel Castings, Carbon, and Alloy, with Tensile
Requirements, Chemical Requirements Similar to Standard
Wrought Grades

 

[ornerynorsk]

If these were my parts, I'd order the parts with chemical certs, annealed, and do the heat treat locally with a reputable firm. I've had very good luck with investment (and other) castings from China, but heat treating can be a mixed bag, depending on your vendor.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.