Hardened Aluminum vs Stainless Steel vs Brass

What are the pros and cons of HA, SS, and Brass?

This is my understanding, but maybe someone can tell me the real differences. HA is cheapest and lightest. Becomes damaged the quickest. SS is heavier, but more durable. Brass I have no idea other then I don't think it rusts such as SS can do. I am most unsure about Brass. I know it costs more because the metal itself is more expensive and I think it is the heaviest of the 3.

Do they have better heat conducting qualities and hence some are better for LED lights?

You pretty much nailed it. Those are the basic qualities, though I would add that aluminum has better heat conductivity than stainless (but less than brass), and stainless neither tarnishes nor requires a hard-coating to strengthen it.

The best light designs use various metals where appropriate -- brass for heatsinking, aluminum or titanium for the body, and steel or titanium for the endpieces. As for lights made from a single metal, it mostly comes down to personal preference, because even cheap lights can make tons of light without overheating nowadays.

Aluminum: high conductivity, light, hard(the aluminum oxide anodising is harder than steel and close to that of sapphire, which is another form of aluminum oxide)
Steel: Lower heat conductivity, twice as heavy, harder than aluminum when the anodising wears off
Brass: never heard of that for body material in flashlights..
Titanium: Moderate conductivity, lighter than steel but heavier than aluminum, stronger than aluminum but weaker than steel. Expensive.

yifu said:

Brass: never heard of that for body material in flashlights..

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Peak has brass bodys, pretty shure there are others.
Maratac has one made out of copper. <- good heatsink.

For a AAA EDC on your key chain go with stainless steel. They are usually so small the extra weight is not noticeable. Aluminum will be all dinged up in a year.

brass is not suitable to use as the shell because it's easily to be oxideze;
stainless steel is not easy to make the oxide layer that who's heat conductivity is quite lower than the steel,so if you make the shell with ss,then you find too hot when use the strong lighting level;
ha doesn't the unacceptable disadvantage,but many torch use brass to make the primary heat structure piece because of it's good heat conductivity.
that's my opinion



eagle

+1 for SS keychainlight.

Had my ReVO SS for quite a while and it looks quite well for what it was used for. Had an anodized aluminium light before and it was dinged up after a short time. Personally I like aluminium lights for EDC as they are light and I like the look of the anodizing. I like SS but not as larger EDC-lights using 18650. Never really got into titanium lights, but I like the look of it too.

rayman

fyrstormer said:

aluminum has better heat conductivity than stainless (but less than brass),

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eagle Z said:

many torch use brass to make the primary heat structure piece because of it's good heat conductivity.

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Actually, aluminum has far better thermal conductivity than brass. In order, the best materials for heatsinking are diamond, silver, gold, copper, aluminum, brass, and finally steel.

Despite being a copper alloy, the other constituents of brass bring the thermal performance way down. Brass still has good electrical conductivity, though.

tylernt said:

Actually, aluminum has far better thermal conductivity than brass. In order, the best materials for heatsinking are diamond, silver, gold, copper, aluminum, brass, and finally steel.

Despite being a copper alloy, the other constituents of brass bring the thermal performance way down. Brass still has good electrical conductivity, though.

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Aluminum is only a better heat conductor than copper per unit of mass, not per unit of volume. Since the aluminum and brass versions of the same flashlight will be the same size, any comparison of their heatsinking ability will therefore always favor the brass.

passive101 said:

What are the pros and cons of HA, SS, and Brass?

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From the standpoint of a purchase decision

Choose aluminum if you want it light weight and are okay with cosmetic dings

Choose stainless if you want it to hold up to abuse




Choose brass for the romance

Peak LED Solutions make a whole bunch of different lights in brass. They work fine.

What are some aa & cr123 copper lights? Some of that stuff looks awesome as it ages.

Edit- & I'm never buying a USED Cu light either (I've read what you freaks do to age them)!

ElectronGuru said:

Choose brass for the romance

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LOL +1

yifu said:

Aluminum: high conductivity, light, hard(the aluminum oxide anodising is harder than steel and close to that of sapphire, which is another form of aluminum oxide)
Steel: Lower heat conductivity, twice as heavy, harder than aluminum when the anodising wears off
Brass: never heard of that for body material in flashlights..
Titanium: Moderate conductivity, lighter than steel but heavier than aluminum, stronger than aluminum but weaker than steel. Expensive.

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Actually, titanium is stronger than steel, unless the steel has been hardeded...and only a few steels are capable of being made harder than titanium.

dosei-45 said:

Actually, titanium is stronger than steel, unless the steel has been hardeded...and only a few steels are capable of being made harder than titanium.

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"Strength" in metallurgy typically refers to tensile or yield strength, which we don't care much about in flashlights. And as I just learned re: brass vs aluminum, such a comparison also depends on if you're talking weight vs volume.

What we really care about is surface hardness, which tells us how well a flashlight will hold up to pocket carry with keys or being dropped etc. There are several measurements -- Rockwell, Mohs, Brinell, etc. But as you say, titanium is harder than most steels except some types of hardened steel.

Some titanium alloys have a higher Rockwell hardness than stainless steel, but as far as I know, non-rustproof carbon steel still has the highest Rockwell hardness of any structural metal.

Something to consider about the specific application of using titanium in flashlights: since titanium weighs half as much as stainless steel, it will hit the ground with considerably less momentum, which reduces the amount of damage that will be done on impact regardless of the Rockwell strength of the alloy it's made from.

Also, yield strength does matter in cases where the light gets crushed between a hard surface and a heavy object, i.e. run-over by a dump truck. It does happen on rare occasion.

fyrstormer said:

Aluminum is only a better heat conductor than copper per unit of mass, not per unit of volume. Since the aluminum and brass versions of the same flashlight will be the same size, any comparison of their heatsinking ability will therefore always favor the brass.

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It sounds like you are confusing thermal conductivity with specific heat capacity. Brass has a higher volumetric heat capacity than aluminum, but a lower thermal conductivity. For an LED flashlight, the higher the heat capacity and the lower the thermal conductivity, the hotter the LED will get as the heatsink soaks up heat but can't readily shed that heat to the body of the light. Therefore, heatsinking ability will clearly not favor brass.

You're right, I got my terminology mixed up. Heat conductivity is not the same as heat capacity, and I was talking about heat capacity. That being said...

A heatsink is nothing more than a place that heat can easily go. Whether the heatsink is also good at conducting that heat to another location, and whether there even is another location for the heat to be conducted to, are separate issues. Water, for example, is pretty bad at conducting heat (in a convection-free environment, anyway), but it's great at absorbing heat, which is why watercooling systems are still so effective despite water's poor heat conductivity. However, its poor heat conductivity is also the reason why car radiators need to have so many tiny channels for the water to flow through, to maximize the amount of water that directly contacts the surface of the radiator. If water were as good at conducting heat as it is at absorbing it, a simple water tank with fins on the surface would be just as effective of a radiator, and a lot more resistant to puncture damage from flying road debris.

Brass functions similarly to water in this respect. While its heat conductivity may not be the greatest, when you factor in its heat capacity per unit of volume, its effectiveness as a thermally-isolated heatsink is better than every other structural metal besides copper. In an application where it can take a long time to saturate the a device with heat, and the device also has the luxury of being able to take its time dissipating that heat later on, brass makes a very effective heatsink. It is perhaps not the best choice for a heatsink in an application that requires constant operation (and therefore constant cooling), but that's not how most flashlights are operated.

I, for one, don't want to serve as my flashlight's "cooling pond" -- I want it to deal with its own thermal needs. A combination of brass and titanium works well for that purpose, and it's not entirely accidental that the lights I carry every day are built with brass heatsinks and titanium shells.

fyrstormer said:

. . . However, its poor heat conductivity is also the reason why car radiators need to have so many tiny channels for the water to flow through, to maximize the amount of water that directly contacts the surface of the radiator. If water were as good at conducting heat as it is at absorbing it, a simple water tank with fins on the surface would be just as effective of a radiator . . . .

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The purpose of a Radiator is transfer heat from water to air. The thermal capacity of air is far worse than water, so a radiator needs a huge surface area in the fins so that there'll be a huge area in contact with air.

Compare a radiator with a boat's water-to-water Heat Exchanger - much smaller surface area - but still not a tank with fins on it.

Yes, a boat's water intercooler still isn't a tank with fins on it, because even seawater doesn't do so well at transferring heat via conduction. Better than air, hence the reduced need for surface area, but both air and water are pretty pathetic conductors of heat compared to almost any metal. The only real benefit water has is it's a fluid, so it can be pumped away from the engine and the heat it's absorbed will go with it.

Anyway, I was just using the water in a car's cooling system as a corollary example of a heatsink that is good at storing lots of heat but not so great at conducting it -- but despite this apparent deficiency it still functions well in its application. The water can absorb lots of heat while sitting in traffic, then dissipate it later on when the car is moving fast and there's lots of airflow, or when the car is parked. Similarly, brass is good at storing a lot of heat, and while it may not be the greatest choice for conducting the heat into the user's hand (ouch! why is this considered a benefit, anyway?), it has plenty of time to cool down after the light is turned off.