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Thread: Help me ID some steel
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10th April 2012, 05:46 PM #1SENIOR MEMBER
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Help me ID some steel
Hi Guys,
I have some steel that I bought from offcuts galore. Its 100mm bar that has been machined down in steps to a final diameter of 60mm.
I was turning it on the weekend and I noticed something strange about it. It was really difficult to cut with carbide as it it seemed to work harden really quickly....yet, using the same feeds and speeds it cut very easily with a sharp HSS tool. I was able to use my home ground HSS tool to reduce the diameter to 50mm for a lenght of 100mm with ease. DOC in both instances was 1mm, speed was 375rpms, feed was .1mm per rev (I think)
When it came time to part off I used my carbide parting off tool and it was almost impervious to this....it only cut in about 2mm before the material was so hard that the carbide tip burnt up.
So I cut it off with the abrasive chop saw...and even this was an effort...it didnt seem to like it at all.
Does anyone have any ideas what this could be? Is it some sort of heat treating steel? If so - how could I test this?
Brendan
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10th April 2012 05:46 PM # ADSGoogle Adsense Advertisement
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10th April 2012, 10:20 PM #2Member
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Do a spark test first there is plenty on web about how to do them and what to look for, is the steel magnetic? Is the bar end colour coded or stamped? Could be a manganese steel though that usually dulls HSS quickly.
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12th April 2012, 01:36 PM #3Senior Member
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Carbide inserts need to be run at higher spindle speeds than HSS . Otherwise the cutting point can rub and dwell in the one spot for too long and absorb excessive heat .
If the steel has a carbon content and already been turned then it is possible that it has already been hardened up by over heating and you are adding more or it's a super hard steel type .
It sounds like a carbon tool steel of some kind.
Coolants are necessary to stop carbon tool steels from getting too hot or turn them a bit at a time allowing cool down periods.
If you want a steel that will not harden up with turning heat it has to be a no carbon type steel like EN36A or a casehardening steel . That way after the turning is done you cane have it case hardened if it has to resist wear .
HSS steel cutters produce less heat as they cut the steel with a sharper edge. Carbide inserts push the steel off the metal and produce more heat but can do that at extreme speeds.
When roughing a hard steel with carbide inserts an insert with a larger point radius is better at resisting point failure due to heat or interrupted cut.
Then switch to the finer point insert to make a light finishing cut.The volume of a pizza of thickness 'a' and radius 'z' is given by pi z z a.
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12th April 2012, 02:46 PM #4
Hi Brendan,
Crossfeed's suggestion is a good one.
If you get a bit of known high carbon steel and grind it first to see what the branching pattern of sparks looks like, then try your unknown steel.
Regards
Ray
PS... 1095 spring steel, is a high carbon steel moderately high in manganese... ( I use it on saw blades ) might be a possible candidate..
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12th April 2012, 08:09 PM #5SENIOR MEMBER
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I possibly have one of these billets as well. Sold as "possibly" 1040 which I think is a medium carbon steel.
I am guessing the heat of previous machining and the cutoff wheel has caused hardening.
Ken
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