Anyone got any experience with hardness testing using the tube that drops a ball bearing from a measured height and its bounce is measured? The higher the bounce the harder the material. My latest pair of heads failed the test, so too did a brand spanking new head ordered in by the machine shop for another customer.That head was fitted with no problems in service.Its predesessor (sp?) was deemed to be no good as it failed the hardness test.
Over to you.... Adrian or SCOOBIDOO?
hardness testing of alloy heads
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discopotato03
- Senior Member
- Posts: 2134
- Joined: Sun Mar 18, 2007 9:29 am
- Location: Sydney
I'm a long time out of my trade but I don't know about the bounce thing .
From memory ... there is a Rockwell C (?) material test where a specifically sized hardened steel ball is pressed a set distance into the material and the loading on the steel ball to sink it in is noted for comparison .
I have asked people about aluminium heads that have had the heat treatment cooked out - don't really know how or if an aluminium casting can be heat treated but the word is that if heads are badly overheated they go soft .
Using the force here but I tend to think that castings could go out of shape through unevenly applied heat stress and critical things may not line up .
The question I can't seem to get an answer to is what happens when aluminium heads are welded ? You'd think with aluminium heads even with pre heating the material gets bloody hot so heat stress and softening ?
I'd be searching Rockwell hardness testing and heat treatment of aluminium cylinder heads .
Still learning . . .
http://www.gordonengland.co.uk/hardness/rockwell.htm
http://www.freepatentsonline.com/4695329.html
http://www.eng-tips.com/viewthread.cfm? ... 194&page=1
http://www.enginebuildermag.com/Article ... pairs.aspx
http://www.rebuiltautoengines.com/subar ... icles.html
http://subaruxt.com/forum/viewtopic.php?f=1&t=8435
From memory ... there is a Rockwell C (?) material test where a specifically sized hardened steel ball is pressed a set distance into the material and the loading on the steel ball to sink it in is noted for comparison .
I have asked people about aluminium heads that have had the heat treatment cooked out - don't really know how or if an aluminium casting can be heat treated but the word is that if heads are badly overheated they go soft .
Using the force here but I tend to think that castings could go out of shape through unevenly applied heat stress and critical things may not line up .
The question I can't seem to get an answer to is what happens when aluminium heads are welded ? You'd think with aluminium heads even with pre heating the material gets bloody hot so heat stress and softening ?
I'd be searching Rockwell hardness testing and heat treatment of aluminium cylinder heads .
Still learning . . .
http://www.gordonengland.co.uk/hardness/rockwell.htm
http://www.freepatentsonline.com/4695329.html
http://www.eng-tips.com/viewthread.cfm? ... 194&page=1
http://www.enginebuildermag.com/Article ... pairs.aspx
http://www.rebuiltautoengines.com/subar ... icles.html
http://subaruxt.com/forum/viewtopic.php?f=1&t=8435