Shrinkage of 13-8ph during Machining!!!
Shrinkage of 13-8ph during Machining!!!
(OP)
My company is turning a 500mm long length of 13/8PH steel bar, in condition A down from 38mm down to 12mm and the machinists have noticed that the length of the bar has reduced by 0.7mm. Note that the reason for using such large diamter bar is that the part in question has two bulbous end features and I confirm this is all before aging the material. The part will be aged to H950 hence the reason for machining before aging. This shrinkage is consistent for the three parts they have currently made and the material is from the same batch.
We have not experienced this before and I can only assume the reason for the shrinkage is due to residual stresses in the material. I assume the material towards the outer diameter of the bar was nominally compressive in nature, which held a central core in tension - as the bar was turned down the tensile stresses were relieved by reduction of the length.
Has anyone else experienced this before or are you able to draw any other conclusions?
Thank you in advanced for your help.
We have not experienced this before and I can only assume the reason for the shrinkage is due to residual stresses in the material. I assume the material towards the outer diameter of the bar was nominally compressive in nature, which held a central core in tension - as the bar was turned down the tensile stresses were relieved by reduction of the length.
Has anyone else experienced this before or are you able to draw any other conclusions?
Thank you in advanced for your help.





RE: Shrinkage of 13-8ph during Machining!!!
RE: Shrinkage of 13-8ph during Machining!!!
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RE: Shrinkage of 13-8ph during Machining!!!
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Plymouth Tube
RE: Shrinkage of 13-8ph during Machining!!!
RE: Shrinkage of 13-8ph during Machining!!!
600mmdia and 500mm thick stock of 316 material is machined to provide a central bore or a step,(noncritical application).
RE: Shrinkage of 13-8ph during Machining!!!
RE: Shrinkage of 13-8ph during Machining!!!
If the length is really critical you will want to do the final aging treatment and then finish machine that dimension.
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Plymouth Tube
RE: Shrinkage of 13-8ph during Machining!!!
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RE: Shrinkage of 13-8ph during Machining!!!
We have seen many cases where we made a cold drawn tube and after heat treat and age the pieces are exactly the size they were at draw.
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Plymouth Tube