Grain growth in BMS

[nigel jones 5Participant @nigeljones5]

Hi. I have a 1/2" shaft which is 1 thou undersize at one end. Would getting it cherry red then quenching it bring it up to size? Or any other technique?

[nigel jones 5Participant @nigeljones5]

[Michael Cox 1Participant @michaelcox1]

Heating the metal will cause grain growth but it is the large grains that grow by absorbing the smaller grains. The total volume of the grains does not change. It addition if you heat it up it will oxidise and you will lose diameter when the oxide scale is removed. There are other factors to consider as well. Firstly there is the possibility of distortion and secondly the metal will be softer.

You do not say what the application is but a very light knurl will increase the size of the shaft and maybe solve the problem.

Mike

[WALLACEParticipant @wallace]

Or possibly turn it down so it’s evenly undersize along its entire length and nickel plate it ?

W

[nigel jones 5Participant @nigeljones5]

thanks guys. I heated it to cherry red then quenched it quickly…result is it has 'grown' by the thou i needed. no scale either. its an axle shaft where the wheel slips on.

[Martin KyteParticipant @martinkyte99762]

Interesting.

Is it not now stressed, and will it not shrink again over sufficiently long time?

Maybe with an issue like this you could heat the undersized end and thump it hard axially?

Martin

[nigel jones 5Participant @nigeljones5]

II did my research and it would seem that although it obviously changes the grain structure for my intended purpose it wont matter, and it wont shrink back.When i worked in fabrication this technique was used to straighten huge steel beams which otherwise could not easily have been straightened.

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