Stress relieving NiHard 1

[Tmoose]

We have some parts cast from A532-82 Class I Type A. Often called NiHard 1.
Mostly sculptured wear liners in the range of 10 to 50 lbs, with thickness between 1/2" and 2".
For decades our drawings have said leave the part in the mold until it cools to 200F before removing it, and Stress relieve at 425F for minimum of 4 hours, based on thickness.

The Nickel Institute offers this reference pdf.

http://www.nickelinstitute.org/~/Me...Ni_HardMaterialDataandApplications_11017_.pdf

On page 18 they talk about stress relief/tempering at no more than 525 F.
The claimed benefits are improved toughness and impact fatigue, with no loss in abrasion resistance.
See attached screenshot.


One of our suppliers says this -
"Stress relieving of Nihard 1 (Riloy 32) was common in the 1960/1970’s and is not done today. Through the years it was deemed as unnecessary. We have not stress relieved any Nihard 1 for any Nihard 1 customer."
I am not aware of any particular broblems with breakage of parts provided by that supplier, but NiHard liners in general have the reputation for not surviving excessive tightening of the bolts that are used secure them.

Has low temparature tempering/stress relief been abandoned, as that supplier claims?

thanks

Dan T

 

[metengr]

I have seen it used in Power Plant applications over the years. In my experience, we have typically used it after stress relieving in critical applications (pump parts). It is application specific, which is why I could see a vendor proclaim this as gospel.

 

[arunmrao]

I am in the thick of the same discussions( for dredger pump front end plate). Though normally, I do not stress relieve, other than allowing the castings to cool in the moulds. This time , I have planned a stress relief at 225C for 4 hours. I am not sure, if it helps, but it will not harm either.


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[EdStainless]

We never bothered for 'solid' parts, but we did for cylinders and impellers.
I am not sure that it really helped, but we thought it did.

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P.E. Metallurgy, Plymouth Tube