4130 flame hardening

[valveboy]

I am attemping to allieviate erosion in several control valves by sleeving the body with a hardened alloy. I have settled on 4130 as it is all that is available short of boring solid round stock. I am considering flame hardening these sleeves to obtain maximum hardness. Wall thickness is .125, 3" O.D. I think that raising the temp to 1600 and then water quench will give me a hardness of at least 35 Rc. Can anyone comment on this. Will I be able to weld the sleeves to the 316L body after hardening, Will the diameter of the sleeve be greater due to Martensite presence, any guesses on shrinkage or growth?

Thanks

 

[arunmrao]

How about powder coating with a ceramic and then finish grind. This is adopted in pump shaft sleeves sucessfully. Through hardening 4130 for you wall thickness will lead to excessive correction after heat treatment.

 

[metengr]

I would agree with arunmrao regarding the distortion of the thin-walled, 4130 steel sleeves from quenching. In addition, welding of a hardened sleeve to the control valve body will result in problems related to potential cracking along the hardened 4130 sleeve base material, and subsequent softening of the hardened sleeve from the heat of welding.

What is the service application and are you sure it is erosion? I would presume these valves are installed and removal for corrective action would be cost prohibitive.

If you need erosion protection, I would look at alternative surface hardening treatments (like nitriding) using a 316L stainless steel sleeve to increase the surface hardness instead of using a low alloy sleeve material. This way you have similar materials between the sleeve and valve body regarding thermal expansion in service (if applicable) and installation of the hardened 316L sleeve would be easier. Something to consider.

 

[swall]

What is the operating fluid? If aqueous or glycol based, you would have the potential for galvanic corrosion, with the sleeve being attacked. If you only need Rc 35, consider 410 stainless instead of 4130.

 

[arunmrao]

You can also consider 17/4 PH sleeves. You can get your hardness .

 

[Carburize]

If it is a severe erosion problem you might want to consider ceramic sleeves and some kind of locking nut to hold them in place.

 

[valveboy]

Thanks for all the help guys! This site is awesome!! A couple of answers to questions, The valve body (316l) cost is around 10K per copy, so sleeving triples its life, Second the fluid, believe it or not is pottato peels with a heavy dose of silicate, at 275 psi. The existing sleeves look to be surgically cut in parabolic shapes near the plug side of the valve. The odd situation here is that yield strengh is not a problem, other than cracking do to the 375 Deg F temp change or pressing the sleeves into the body. As far as welding the sleeve, as I mentioned these sleeves will be pressed into the body, I have cpnsidered not welding them at all, the welds would be a insurance that the sleeve would not move.
I think I should back up for a moment, with all this great information, and ask, is there a better alloy out there that is available. As i mentioned finding any sort of tubing with a <.250 wall is difficult, and I havent found anyone loccally who who be willing to bore round stock, especially if it is some difficult alloy. Is there an alloy that comes forged, or DOM that has an inherent hardness? I have considered using inside race material, however in this particular situation, lead times are prohib
ative, as it is non standard size. Thanks again.

 

[unclesyd]

I would suggest using a Stellite Sleeve which can be purchased in most sizes. We used this approach on quite a number of projects using mainly Stellite 6B sleeve material.
You can contact the following company for information.

They did have a great tech group at one time, hopefully they still do.

http://www.stellite.com/default.asp

 

[rorschach]

or for that matter you can do what is commonly done in wellhead control equipment, don't make the whole thing out of SS, use carbon steel and weld overlay it with the alloy best suited to the purpose, in this case, any number of the Stellite alloys would be among my short list. and then finish machine the weld overlay. you kill two birds with one stone,. you get the cost savings of CS, AND you get the environmental compatability of a highly alloyed material without having to cast the whole dang thing out of it.