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How to measure surface hardness and core hardness of hex cap screw? Question
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Posted by: eddyhtmok

10/08/2004, 05:23:42

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Hi all,

Does anyone know how to measure a hex cap screw (Grade 5)for its core hardness and surface hardness?

The requirement is as below,

Surface hardness: Rockwell 30N -- 54 MAX

Core hardness: Rockwell C34 MAX, C25 MIN

Please help, Thanks alot!

 

rgds,

Eddy

 







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Re: How to measure surface hardness and core hardness of hex cap screw?
Re: How to measure surface hardness and core hardness of hex cap screw? -- eddyhtmok Post Reply Top of thread Forum
Posted by: zekeman

11/01/2004, 09:44:00

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I would just use a Rockwell tester for the surface , then grind away enough surface to get to the "core" , and repeat the testing for the subsurface.







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Re: How to measure surface hardness and core hardness of hex cap screw?
Re: How to measure surface hardness and core hardness of hex cap screw? -- eddyhtmok Post Reply Top of thread Forum
Posted by: rjbeng

10/16/2004, 12:43:56

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Mike is correct if all you need is superficial hardness. I would assume you are looking at a failure or a vendor qualification. If so you may need to go into a little more detail. I have had instances were superficial harnesses looked alright but the micro hardness revealed that the case depth varied along the axis of the bolt causing a failure at half the rated value. You may want to send a sample out to lab for microstructure and hardness analysis. Your supplier may also be able to supply you with this information upon request. They should/hopefully be performing a lot check after carburizing. Although, lot checks do not guarantee that all of the bolts in that lot have the same heat treat.






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Re: How to measure surface hardness and core hardness of hex cap screw?
Re: How to measure surface hardness and core hardness of hex cap screw? -- eddyhtmok Post Reply Top of thread Forum
Posted by: mikebull

10/08/2004, 08:00:40

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For the case you would use a hardness tester, if thats OK the core is probably OK. To check the core exactly though you woud need to cut the bolt.






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Re: How to measure surface hardness and core hardness of hex cap screw?
Re: Re: How to measure surface hardness and core hardness of hex cap screw? -- mikebull Post Reply Top of thread Forum
Posted by: eddyhtmok

10/10/2004, 22:06:00

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Hi Mikebull,

 

Thanks for your help!

 

best regards,

Eddy







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