Heat Treat Standards on print

[CR100]

When creating manufactuering prints is their a standard on how to specificy the strenght the of the material or Heat treat procedure?


For example, I have specifcied a print for a forged valve. Can I just specify the Yield Strength, Tensile Strength and Elongation. Or is there a standard I should reference.

Any help is appreicated.

 

[mrfailure]

Most commonly, designers select a material meeting their mechanical requirements by calling out a material specification that includes mechanical properties and may include heat treating requirements.

For example, ASTM A182 specifies alloy and stainless steel valve forgings. This specification includes both mechanical properties and specified heat treatments.

If you need to modify from specified properties, you can call this out in the drawing. I would strongly discourage putting only specified mechanical properties or heat treatments on a drawing as you may end up with material of poor quality with other unacceptable properties.



Aaron Tanzer

http://www.lehightesting.com

 

[Wrenchbender]

Yes, there are many industrial, federal and military standards for spec'ing just about anything, including heat treatments and materials. Its best to reference one of these standards for accuracy, credibilty, and so as not to have to reinvent. Search them out for something appropriate, but don't over-spec.

Examples: For a steel forging there is ASTM A788 and hundreds of others. You can prob find one pertaining to valves. For heat treatment of steel, there's SAE-AMS-H-6875 (or MIL-H-6875, same). Some are available free, online; others you have to buy.

 

[swall]

In basic terms, the procedure, for low alloy steels, is to specify a Rockwell hardness range based on the desired tensile strength of the product. And a material description, of course. Example: SAE 4140 steel, neutral harden and temper to Rc 38-42. If there are other requirements, such as a heat treat procedure like AMS H-6875, you add that to the material callout.

 

[mrfailure]

Drawings which call out a material designation (i.e. Type 1020, 304, etc.) can be problematic because that designation ONLY guarantees composition. You may not get the quality you really require by calling this out even in conjunction with desired properties and/or heat treatment. Whenever possible, you should instead start by using an actual specification (e.g. ASTM/ASME, DIN, EuroNorm, JIS, etc.) suitable for the type of material you are going to use and the appropriate grade of alloy within that spec. You can always then call out to meet higher quality for specific properties in your drawing if you really have to.

Aaron Tanzer

http://www.lehightesting.com

 

[TVP]

Good advice from the others. If you are looking for an internationally developed standard to follow, ISO 15787 Technical product documentation — Heat treated ferrous parts — Presentation and indications is one example. It basically standardizes terminology, etc. for general drawing specification like the one provided by swall above. Here is an excerpt:


quench hardened and tempered
according to HTO

(59⁺⁴₀) HRC


HTO is an abbreviation for Heat-Treatment Order, which would be a more specific document identifying the process requirements.

 

[israelkk]

swall

MIL-H-6875 only minimum and maximum tensile strength and not Rockwell hardness. Specifying Rockwell hardness instead of tensile strength doesn't comply with MIL-H-6875.

 

[swall]

Yes, isrealkk, I am familiar with aerospace heat treatment standards. The original poster seemed to be looking for guidance on how to start and I gave him that. The others have filled in the gaps, as I am sure more will.

 

[CR100]

What we currently have done is for example,

1045 Q&T
Min 75 ksi Yeild
Min 100 ksi tensile
Min Elongation 15%
Hardness Approx. HRC30
(MIL-H-6875)

I would think this is enough, but I would think I would need to mentioned to descale the part as well. The challenge comes in when case hardening, I would think I would just mention to core hardness and the depth of the case.

 

[salmon2]

You have received a lot of comments, I will comment your last post since this applies to your current situation.
-Your HRC seems high for the yield/tensile unless this is a general hardness max you have to stay under.
-1045 is usually not a very good candidate for QT unless the diameter is small and impact toughness is not concerned.
-your coverage on mechanical properties is pretty good now, except no Charpy. Again, this is up to your application and design code, if any.
- you probably need chemistry and NDE results for critical parts.
- descale? Not a really concern usually. Is forging your final step? If yes, you may have to specify surface condition and really a surface NDE will be best. You never got good finish from hot forging.
- 1045 is not case hardening chemistry, I assume you meant another chemistry when you said case...
- for case hardening, you would want to specify case hardness and depth required, and sure core hardness as well.

Just some random comments, hope helpful.

 

[TVP]

If by case hardening you mean surface hardening by induction or flame, then ISO 15787 also describes how to specify this type of requirement. Here is an example:

surface hardened (with the area indicated by a type 04.2.1 long-dashed dotted wide line, in accordance with ISO 128-24:1999)
620 ₀⁺¹⁶⁰ HV30
SHD 500 = 0.8 ₀^+0.8

 

[CR100]

Salmon2, a couple of the numbers I used were to illustrate what is typically on the print. The numbers may not be correct, I was more focused on how to explain or call them out on the print correctly.


Thanks for all the feedback though.