Examples of hardened steel in common household items
July 28, 2019 5:16 PM Subscribe
Can you help me come up with a list of examples of uses of hardened steel in everyday life?
I'm helping someone with a presentation and we'd like to come up with a good list of common things that you might find in an ordinary home that contain hardened steel. If possible, I'd like to rank this list from most hard to least, so for example something like this (fictional numbers):
Ball bearing in electric appliance motor - HRC 67
Hacksaw blade - HRC 62
Screwdriver tip - HRC 55
[please correct any of those numbers if I got them wrong, they were based on very cursory searches]
In particular, I would be most interested in unexpected examples, such as the ball in a ball point pen (I'm just guessing - I think I heard that is very hard steel?) Hopefully, it's a lot more varied that a list of different kinds of blades. Examples from car parts would also be good.
In addition, if anyone would like to explain the reason that these items need to be of the specified hardness, that would be awesome in case there are follow up questions for my presenter friend.
Thank you.
I'm helping someone with a presentation and we'd like to come up with a good list of common things that you might find in an ordinary home that contain hardened steel. If possible, I'd like to rank this list from most hard to least, so for example something like this (fictional numbers):
Ball bearing in electric appliance motor - HRC 67
Hacksaw blade - HRC 62
Screwdriver tip - HRC 55
[please correct any of those numbers if I got them wrong, they were based on very cursory searches]
In particular, I would be most interested in unexpected examples, such as the ball in a ball point pen (I'm just guessing - I think I heard that is very hard steel?) Hopefully, it's a lot more varied that a list of different kinds of blades. Examples from car parts would also be good.
In addition, if anyone would like to explain the reason that these items need to be of the specified hardness, that would be awesome in case there are follow up questions for my presenter friend.
Thank you.
All sorts of springs, from car suspensions to the lid latch on a food processor to the springs that keep carbon brushes pressed against the armatures of electric motors to the winding springs in mechanical timers and wristwatches. Various parts of power tools — not just blades and bits but parts that grip blades and bits, e.g. drill chucks. Drywall screws. Hammers. Padlocks. Wrenches. Files. Axels.
Components that need to store energy, resist deformation, return to their original shape after being deformed, cut, tolerate impact, tolerate encounters with other hard or abrasive materials... the stuff is everywhere.
posted by jon1270 at 6:16 PM on July 28, 2019 [3 favorites]
Components that need to store energy, resist deformation, return to their original shape after being deformed, cut, tolerate impact, tolerate encounters with other hard or abrasive materials... the stuff is everywhere.
posted by jon1270 at 6:16 PM on July 28, 2019 [3 favorites]
Crowbars, shovels, hatchets, electric toothbrushes, blenders... as jon1270 points out this stuff is everywhere; it comes down to what you consider an ‘ordinary home’. I have a coffee grinder and a hatchet and carabiners but I know plenty of folks who own none of those.
posted by SaltySalticid at 6:46 PM on July 28, 2019
posted by SaltySalticid at 6:46 PM on July 28, 2019
Scissors? There are different types for different applications, from kitchen scissors to office/paper scissors to sewing/fabric scissors, that need different characteristics. I wasn't able to quickly find a ranking of these in terms of hardness needed, but I bet it's out there somewhere.
posted by LobsterMitten at 7:01 PM on July 28, 2019
posted by LobsterMitten at 7:01 PM on July 28, 2019
I've got a bolt cutter and a hand axe, crow bar, tire iron, that thing in the trunk of my car to lift my car for tire changes, and a hand-push mower that likely has a few hardnendededed steel gears in it.
posted by tilde at 7:02 PM on July 28, 2019
posted by tilde at 7:02 PM on July 28, 2019
Well, plenty of ordinary homes have firearms, which are mainly hardened steel alloys.
I've got a cold chisel I made in high-school from mild steel - I've cut oil drums in half with it. I hardened this myself learning to read the colours run before I repeatedly quenched it in oil.
Sewing needles - hardness 1Mb pdf - gosh there's some odd things on the web
posted by unearthed at 7:11 PM on July 28, 2019 [1 favorite]
I've got a cold chisel I made in high-school from mild steel - I've cut oil drums in half with it. I hardened this myself learning to read the colours run before I repeatedly quenched it in oil.
Sewing needles - hardness 1Mb pdf - gosh there's some odd things on the web
posted by unearthed at 7:11 PM on July 28, 2019 [1 favorite]
They are a kind of spring, though I don't think most people see them that way: split key rings.
I've heard that steel cables are often carbon steel of high hardness. For a while some guy in Seattle was cutting inch+ thick steel cable into 10-15 inch lengths and forging all but 5 or 6 inches of it into a blade, and leaving the rest of it as cable for the handle, then selling the results at flea markets. It was by a long way the roughest and most uncomfortable knife handle I have ever touched.
Some bicycle spokes used to be chrome-plated high carbon and very springy steel. I have a couple of boxes of those made by DT that I'll never get around to doing anything with that I bet are superior in some important ways to the stainless spokes that drove them from the field.
Machine screws are often very high quality steel to minimize the chances that they'll break off in the body they're screwed into, and they're often harder steel than screwdriver blades in order to resist stripping by those blades.
posted by jamjam at 7:26 PM on July 28, 2019 [3 favorites]
I've heard that steel cables are often carbon steel of high hardness. For a while some guy in Seattle was cutting inch+ thick steel cable into 10-15 inch lengths and forging all but 5 or 6 inches of it into a blade, and leaving the rest of it as cable for the handle, then selling the results at flea markets. It was by a long way the roughest and most uncomfortable knife handle I have ever touched.
Some bicycle spokes used to be chrome-plated high carbon and very springy steel. I have a couple of boxes of those made by DT that I'll never get around to doing anything with that I bet are superior in some important ways to the stainless spokes that drove them from the field.
Machine screws are often very high quality steel to minimize the chances that they'll break off in the body they're screwed into, and they're often harder steel than screwdriver blades in order to resist stripping by those blades.
posted by jamjam at 7:26 PM on July 28, 2019 [3 favorites]
Bike freewheels are usually made of very hard plated carbon steel, and so are some parts of typical bike chains.
posted by jamjam at 7:29 PM on July 28, 2019 [1 favorite]
posted by jamjam at 7:29 PM on July 28, 2019 [1 favorite]
Ball point pen bearings are made of tungsten carbide (as I found to my dismay when I x-rayed one and couldn’t see through the darn thing.)
Heavy duty bike locks and some bike frames are. I’d guess that some other parts might be as well, like the chain, but I’m not finding things easily.
posted by tchemgrrl at 7:31 PM on July 28, 2019
Heavy duty bike locks and some bike frames are. I’d guess that some other parts might be as well, like the chain, but I’m not finding things easily.
posted by tchemgrrl at 7:31 PM on July 28, 2019
Many shoes!
- Steel-toed work boots
- Some shoes have a hardened steel shank to improve stiffness in the midfoot.
- Heels narrower than a certain width (most famously, stilettos) are strengthened with a steel shaft.
posted by meaty shoe puppet at 8:18 PM on July 28, 2019
- Steel-toed work boots
- Some shoes have a hardened steel shank to improve stiffness in the midfoot.
- Heels narrower than a certain width (most famously, stilettos) are strengthened with a steel shaft.
posted by meaty shoe puppet at 8:18 PM on July 28, 2019
The wire in good quality flexible ducting (the silvery accordion stuff) can be remarkably hard, Rockwell C 60. My aircraft shears still bear a nick where I learned this lesson.
posted by aramaic at 8:31 PM on July 28, 2019
posted by aramaic at 8:31 PM on July 28, 2019
As mentioned above, springs of all types are hardened. There are a lot of springs in the world! The heat treatments that spring steel goes through are fascinating in their own right.
The one that really surprised me was piano wire, which is not just hardened but at HRC 41-60 (according to random search result) is actually one of the harder things that one can imagine actually cutting around the house. It's certainly the hardest thing a typical pair of good bolt cutters is rated to deal with; cheap bolt cutters can't even do the job.
posted by GSV The Structure of Our Preferred Counterfactuals at 9:18 PM on July 28, 2019
The one that really surprised me was piano wire, which is not just hardened but at HRC 41-60 (according to random search result) is actually one of the harder things that one can imagine actually cutting around the house. It's certainly the hardest thing a typical pair of good bolt cutters is rated to deal with; cheap bolt cutters can't even do the job.
posted by GSV The Structure of Our Preferred Counterfactuals at 9:18 PM on July 28, 2019
Response by poster: I really appreciate the answers so far but I was really hoping for quantifiable hardness ratings like in the example so that we can demonstrate a spectrum of hardness from least to most.
posted by Otto Franz Joseph Leopold von Soxen-Puppetten at 11:50 PM on July 28, 2019
posted by Otto Franz Joseph Leopold von Soxen-Puppetten at 11:50 PM on July 28, 2019
Shun chef knives are hardened to 60-61 or 61-62 (see here). Wusthof knives are around 56-58. (Rockwell hardness)
There is a list here of various types of steel and typical items made thereof as well as Rockwell hardness.
posted by Comrade_robot at 2:18 AM on July 29, 2019 [1 favorite]
There is a list here of various types of steel and typical items made thereof as well as Rockwell hardness.
posted by Comrade_robot at 2:18 AM on July 29, 2019 [1 favorite]
One question to ask is exactly how precise you want the term "hardened" to be in this context. Various steels have different hardness inherent in their composition - as a general rule of thumb more carbon = more hardness in the as-rolled condition.
However (as your tags suggest you are aware) heat treatment and hot- or cold-working can change the through hardness and the surface hardness of items made of steel. Something that is hard all the way through is more subject to shatter once it's beyond its limits. Many things will be relatively soft and springy inside, but very hard on the surface, so that they can resist wear but not shatter.
Looking at my work desk, the steel things I see include:
-serrated edge on my desktop tape dispenser - probably work hardened when it was blanked.
-binder clip: the black part is not very hard at all, but the looped bits are.
-Paper clip: not hard.
-Pocket knife: blade is very very hard on the surface, but soft inside. (I've broken one, so I've seen it).
-Scissors: same as knife.
-Ball bearing: balls are very very very hard. Races are probably surface hardened. Ball cage is dead soft.
-Die spring: Tough, not hard. Easily knicked with pocket knife, cutting it is another matter entirely.
posted by notsnot at 6:48 AM on July 29, 2019
However (as your tags suggest you are aware) heat treatment and hot- or cold-working can change the through hardness and the surface hardness of items made of steel. Something that is hard all the way through is more subject to shatter once it's beyond its limits. Many things will be relatively soft and springy inside, but very hard on the surface, so that they can resist wear but not shatter.
Looking at my work desk, the steel things I see include:
-serrated edge on my desktop tape dispenser - probably work hardened when it was blanked.
-binder clip: the black part is not very hard at all, but the looped bits are.
-Paper clip: not hard.
-Pocket knife: blade is very very hard on the surface, but soft inside. (I've broken one, so I've seen it).
-Scissors: same as knife.
-Ball bearing: balls are very very very hard. Races are probably surface hardened. Ball cage is dead soft.
-Die spring: Tough, not hard. Easily knicked with pocket knife, cutting it is another matter entirely.
posted by notsnot at 6:48 AM on July 29, 2019
Most kitchen knives are hardened to between 57 and 63 Rockwell. The notable exception is high carbon steel knives, which are considerably softer.
posted by slkinsey at 7:13 AM on July 29, 2019
posted by slkinsey at 7:13 AM on July 29, 2019
This thread is closed to new comments.
Carabiners for gyms, rock climbing, and rope access come in hardened stainless steel varieties, as do the maillons which are often part of climbing and industrial harnesses. They're hardened to meet specifications to do with minimum breaking strain (since they're designed to let people hang from them). Similarly, the shackles that are used to secure trailers and caravans to cars (U-bolts, D-bolts) are made of strengthened metals to guarantee their load capacity.
posted by Fiasco da Gama at 5:39 PM on July 28, 2019