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Osvaldo Cristo
12-11-2019, 2:51 PM
It was the first time I purchased some deck screws, as stated on the box label. It also states the material is stainless steel. Made in Taiwan. It looked great as I got them at a reasonable price...

...but I found something odd when I arrived at my workshop: my strong magnet barely provoke reaction when close and even contacted with a such screws. They are practically amagnetic. It is strange as it would be mainly iron... :eek::confused::confused:

I would appreciate if you that are consumer for deck screws could explain me why Asian stainless steel is different from my other stainless steel experience.

Thanks in advance.

Lee Schierer
12-11-2019, 3:03 PM
Only some stainless in the 400 series is magnetic and can also be hardened. Most 300 series stainless steels are non-magnetic. Your screws are likely a 300 series stainless. They are still stainless steel and they should work okay, but may be softer than steel screws.

The following types of stainless steel are typically magnetic:

Ferritic Stainless Steels such as grades 409, 430 and 439
Martensitic Stainless Steel such as grades 410, 420, 440
Duplex Stainless Steel such as grade 2205

Doug Garson
12-11-2019, 3:07 PM
There are several types of stainless steel, they have different properties and uses. Does the box say what grade of stainless steel?

A basic stainless steel has a 'ferritic' structure and is magnetic. ... However, the most common stainless steels are 'austenitic' - these have a higher chromium content and nickel is also added. It is the nickel which modifies the physical structure of the steel and makes it non-magnetic.

Osvaldo Cristo
12-11-2019, 3:45 PM
There are several types of stainless steel, they have different properties and uses. Does the box say what grade of stainless steel?

[...]
It is the nickel which modifies the physical structure of the steel and makes it non-magnetic.

It is a surprise for me. I knew usually stainless steel contains nickel but it is the first time I read nickel can change so dramatically the properties of a iron alloy. Thanks both of you to educate me.

Osvaldo Cristo
12-11-2019, 3:47 PM
Only some stainless in the 400 series is magnetic and can also be hardened. Most 300 series stainless steels are non-magnetic. Your screws are likely a 300 series stainless. They are still stainless steel and they should work okay, but may be softer than steel screws.

The following types of stainless steel are typically magnetic:

Ferritic Stainless Steels such as grades 409, 430 and 439
Martensitic Stainless Steel such as grades 410, 420, 440
Duplex Stainless Steel such as grade 2205

Very comprehensive answer. Thank you very much! Now I got it.

Frank Pratt
12-11-2019, 8:18 PM
You want to be careful when using SS screws. The are much weaker than conventional steel construction screws.

Osvaldo Cristo
12-11-2019, 9:37 PM
Only some stainless in the 400 series is magnetic and can also be hardened. Most 300 series stainless steels are non-magnetic. Your screws are likely a 300 series stainless. They are still stainless steel and they should work okay, but may be softer than steel screws.

The following types of stainless steel are typically magnetic:

Ferritic Stainless Steels such as grades 409, 430 and 439
Martensitic Stainless Steel such as grades 410, 420, 440
Duplex Stainless Steel such as grade 2205

Humm... just wandering, could the navy to use series 300 stainless alloys to construct mine hunter vessels?

Lee Schierer
12-11-2019, 10:13 PM
Humm... just wandering, could the navy to use series 300 stainless alloys to construct mine hunter vessels?
No 300 series stainless is prone to stress corrosion cracking in the presence of chloride (salt).

Bill Dufour
12-11-2019, 11:08 PM
The navy could use fiberglass for hulls but the engine and pumps/radios would still be magnetic.
My father worked with a guy who was in the US navy during world war 2. They took a millionaires sailing yacht and removed the radio, engine, generators etc. basically anything metal was removed. Since he had been in the sea scouts he was in charge of a small crew. They based in Bermuda? and sailed around for two weeks or so, until the food ran out, looking for mines. If they saw any they were supposed to shoot it with a rifle they had on board. He did this for about one year and never saw anything.
After the war was over the engines etc were reinstalled and the boat was given back to the owner. He would not have been allowed to sai lit to sea during the war anyway.
Bill D

Osvaldo Cristo
12-12-2019, 1:26 PM
No 300 series stainless is prone to stress corrosion cracking in the presence of chloride (salt).

...so it does not look a good material for deck screws, no? It is common to have decks around swimming pools and at beach homes.

Tom M King
12-12-2019, 1:31 PM
My favorite deck screws are Deckmate with "Star Drive" heads. Star Drive is actually a T25 TORX.

What I don't like about stainless screws for decking is that they are soft. The softness means that if you hit a knot, or some hard spot in a board, or joist, the driver bit will cam-out the head, leaving you to have to use Vise-Grips to back the screw out, and then try another one. Also, when the time comes that you might be able to turn a deck board over, the percentage of the stainless screws you can get back out is not high.

The T25 Deckmates can be backed out any time in the future, and the finish lasts as long as the deck boards do.

Jim Koepke
12-12-2019, 3:18 PM
My favorite deck screws are Deckmate with "Star Drive" heads. Star Drive is actually a T25 TORX.

With the help of my grandson we built two decks using Deckmate screws. Not a single problem.

My use of Stainless Steel deck screws with Robertson drive (square drive) always seems to have problems with the socket stripping.

jtk

Frank Pratt
12-12-2019, 5:02 PM
Just a side note with regards to camming out of the screw head; an impact driver, as opposed to a drill, will help tremendously in that regard.

Torx are good, but the screw won't stay on the bit nearly as well as with Robertson. With decent screws & driver bits, camming out will never be a problem with Robertson drive.

Aaron Rosenthal
12-13-2019, 12:02 AM
I've built many a deck using 300 series SS screws, and the best way I found to keep the cam out issue at bay was:
Pre-drill with an appropriate drill/countersink unit;
Bees way the thread (paraffin also works, but too dangerous);
Use the impact driver to run the screw into the pre-drilled hole;
Repeat another 10,000 times.
I have found one issue with the stainless is the small heads: after 8-10 years, the wood movement loosens them up.

Frank Pratt
12-13-2019, 10:25 AM
Bees way the thread (paraffin also works, but too dangerous)

How is paraffin too dangerous?

Jim Koepke
12-13-2019, 11:13 AM
How is paraffin too dangerous?

This was going to also be my question.

jtk

Aaron Rosenthal
12-13-2019, 1:21 PM
How is paraffin too dangerous?


Was building for families with kids around; flammable, plus the fumes. Used wax where I could control the safety.

David Bassett
12-13-2019, 1:35 PM
Was building for families with kids around; flammable, plus the fumes. Used wax where I could control the safety.

Are US and Canadian "paraffin" different? (I know British "paraffin oil" is US "kerosine" which is flammable.)

US version of paraffin is a wax which is traditionally used in kitchens across the US for sealing "canned" (i.e. jarred, preserved) goods. Yeah, it's flammable, but you have to try really hard. (I imagine about as hard as it would be to burn beeswax.)

Frank Pratt
12-13-2019, 5:47 PM
Was building for families with kids around; flammable, plus the fumes. Used wax where I could control the safety.

There are no fumes from paraffin wax & you can't even light it on fire with a match unless some kind of wick is involved. Most everything in the house will light on fire easier than paraffin.

Jim Koepke
12-13-2019, 7:35 PM
Are US and Canadian "paraffin" different?

Interesting point if this is the case.

jtk

Frank Pratt
12-13-2019, 7:57 PM
Are US and Canadian "paraffin" different?

Not in this part of Canada.

Lee Schierer
12-13-2019, 9:45 PM
I prefer beeswax over paraffin because paraffin crumbles while beeswax sticks to the threads. It also smells better.

Tom M King
12-13-2019, 9:50 PM
Does the wax make sure you can get 100% of them back out in 20 years? I've never seen a Star Drive screw that wouldn't come right back out. Here, we turn dock boards, and deck boards over when the tops are badly checked, which is after about 20 years.

Also, I've never put wax on a single one of the thousands we've run in.

keith wootton
12-14-2019, 12:17 AM
i build docks. i would echo what others have said about the softness and breaking of ss screws. if you need to use stainless because a hostile enviornment requires it for corrosion resistance, we had better luck with 2 1/2 inch screws instead of 3 inch. dramatic reduction in breakage. we also did switch to deck mate ceramic coated with torx drive. one fifth the cost, and no breakage. they hold up for us, but freshwater. ymmv

Rich Engelhardt
12-14-2019, 5:41 AM
Pre-drill with an appropriate drill/countersink unit;
Bees way the thread (paraffin also works, but too dangerous);
Use the impact driver to run the screw into the pre-drilled hole;
Repeat another 10,000 times.
Way too much "screwing around" (groan - I know - bad me/bad pun :D :D ).

I just use Deckmate screws and an 18V Makita impact driver.

Aaron Rosenthal
12-19-2019, 3:22 PM
Been away for a while.
Had 2 nasty experiences with paraffin, once overseas where it IS kerosene, and once locally where it spilled, someone slipped and I vowed never to use it again. Didn't know there was a difference between Middle Eastern and North American paraffin flammability.
Still, I use beeswax, just ingrained habit I guess.

Mel Fulks
12-19-2019, 5:18 PM
I think bee's wax works the best. And the fact that it seems gummy and unlikely to work , is kinda entertaining.

dennis thompson
12-20-2019, 7:16 AM
Only some stainless in the 400 series is magnetic and can also be hardened. Most 300 series stainless steels are non-magnetic. Your screws are likely a 300 series stainless. They are still stainless steel and they should work okay, but may be softer than steel screws.

The following types of stainless steel are typically magnetic:

Ferritic Stainless Steels such as grades 409, 430 and 439
Martensitic Stainless Steel such as grades 410, 420, 440
Duplex Stainless Steel such as grade 2205

This is why I love this website. Only here could you get an intelligent explanation of eight different types of stainless steel screws.
Of course only on this website could you get 10 or twenty people talking about screws:)
Lee, how do you know this stuff?

Mike Henderson
12-20-2019, 12:24 PM
...
Bees wax the thread (paraffin also works, but too dangerous);

I did some experiments between beeswax and paraffin wax and found that paraffin wax was "slicker" than beeswax. Beeswax tended to "stick" somewhat. This was for uses other than screws so it may not apply to screws.

And paraffin wax is certainly not dangerous.

Mike

James Waldron
12-23-2019, 10:08 PM
Humm... just wandering, could the navy to use series 300 stainless alloys to construct mine hunter vessels?


Traditional wooden hull vessels - including mine sweepers - are fastened with bronze screws and bolts, etc. Avoids corrosion nicely, thank you. Still going on in traditional boat building circles.

Patrick Walsh
12-24-2019, 7:53 AM
I’ll second the deck mate. I use them for everything when doing general construction. They never strip or snap.

I did just do my deck and use 316 stainless screws countersunk. Not sure why over the deck mate but that what’s I did. Every hole countersunk. Most clients would never want to pay for the labor involved in pre drilling and bunging like six zillion screws.

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