Heat Treatment - Mar Quenching Vs. Sealed Quenching
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    Default Heat Treatment - Mar Quenching Vs. Sealed Quenching

    I manufacture thin walled, bearing outer like components from bearing steel (SAE 52100). After machining it undergoes heat treatment where it attains 62-63 HRc of hardness.

    Currently I use Mar Quenching method (outsourced) to prevent temperature shock of quenching in Oil. Recently I came to know that few of my competitors heat treat by Sealed Quenching method.

    Post heat treatment, they are polished in vibratory and centrifugal polishing machines and later hard chrome plated.

    I discussed with my service provider and he is unable to point to any major benefit of using Sealed Quenching over Mar Quenching.

    Can the experts here please guide me in the matter.

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    Quote Originally Posted by Prasham View Post
    I manufacture thin walled, bearing outer like components from bearing steel (SAE 52100). After machining it undergoes heat treatment where it attains 62-63 HRc of hardness.

    Currently I use Mar Quenching method (outsourced) to prevent temperature shock of quenching in Oil. Recently I came to know that few of my competitors heat treat by Sealed Quenching method.

    Post heat treatment, they are polished in vibratory and centrifugal polishing machines and later hard chrome plated.

    I discussed with my service provider and he is unable to point to any major benefit of using Sealed Quenching over Mar Quenching.

    Can the experts here please guide me in the matter.
    I should think that YOUR vendor will KNOW best at what the difference is, and what if any changes could be expected from using the other HT method.

    Doo you think your vendor is unable to offer the alternative method, so discredits any changes to it ?

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    Quote Originally Posted by digger doug View Post
    I should think that YOUR vendor will KNOW best at what the difference is, and what if any changes could be expected from using the other HT method.

    Doo you think your vendor is unable to offer the alternative method, so discredits any changes to it ?
    "Digger Ox" returns!

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    Quote Originally Posted by digger doug View Post
    Do you think your vendor is unable to offer the alternative method, so discredits any changes to it?
    That's probably why Prasham is asking the question here.

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    Quote Originally Posted by Joe Gwinn View Post
    That's probably why Prasham is asking the question here.
    Obviously that's the reason. He only does Oil and Mar Quenching.

    Since this component is Hard chrome plated after Heat Treatment, I don't think there could be any other benefits except lesser scale formation (grey/black spots colour) and lesser distortion.

    Since the product is discarded after depletion of hard chrome layer, I don't think its microscopic structure or consistency in hardness kind of parameters would come into play in performance of the component.

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    Quote Originally Posted by Prasham View Post
    Obviously that's the reason. He only does Oil and Mar Quenching.

    Since this component is Hard chrome plated after Heat Treatment, I don't think there could be any other benefits except lesser scale formation (grey/black spots colour) and lesser distortion.

    Since the product is discarded after depletion of hard chrome layer, I don't think its microscopic structure or consistency in hardness kind of parameters would come into play in performance of the component.
    I think that the only way to tell is to order some samples, where a run machined from the same batch of steel is split into two groups, one Oil quenched, the other MAR quenched, and see how it goes.

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    Quote Originally Posted by Prasham View Post
    I manufacture thin walled, bearing outer like components from bearing steel (SAE 52100).

    I discussed with my service provider and he is unable to point to any major benefit of using Sealed Quenching over Mar Quenching.

    Can the experts here please guide me in the matter.
    The mar quenching here is just a "hot oil" agitated bath quench… I hadn’t heard the “sealed quench” term used before now & looked it up. It’s just an oil quench where the parts stay in a protected atmosphere while being shuttled to the quench tank… Lindberg HT had those in the ‘70’s & your parts may be run in one this batch & then moved to an older furnace with the open air quench tank the next batch. The older furnaces had a fuel rich flame curtain to “soot the surface” going in and coming out. Everything got cleaned anyway afterwards.

    The matensite start point of 52100 is higher than any oil I know can take (even synthetic). So the parts still get quenched pretty hard. If you’re nuts anal about 52100 with bearing race shapes & sections “Gleason press quench” process used to be the last word here.

    Good luck,
    Matt


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