Trouble with Heat Treatment of 1022 steel Fasteners 1

[J G]

I am making special fasteners from 1022 steel.

The screw needs a high surface hardness (58-60 HRc) but should be able to bend also (5-7 degrees).

In my heat treatment process I get the hardness but the screw does not pass the bend test. It is brittle and breaks.

HELP !

 

[BrianPetersen]

Stupid mechanic here who works on automotive body-in-white, not a metallurgist. That looks like a wood screw or sheet-metal screw. There is no way you are going to self-tap 6mm of steel plate, even mild steel, with a screw like that.

Option 1 if you can get to the backside, a proper screw and hex nut with normal everyday M6x1.0 threads. No self-tapping no nothing. Drill a clearance hole, position the nut and screw, tighten, done.

Option 2 if you can't get to the backside, drill and tap a normal M6x1.0 hole and use a normal off-the-shelf M6 screw. Done.

Option 3 if you don't want to drill and tap, weld a weld-nut to the backside and use a normal off-the-shelf M6 screw. Done. We projection-weld weld nuts to the backside of sheet metal parts all the time. In my home shop, I've MIG-welded normal nuts to the backside of steel brackets many times.

Now, over to you. Wny won't these "standard off-the-shelf" solutions work for you?

Self-tapping screws are for sheet metal ductwork in a house. And I've never seen one that long.

I've seen self-tapping screws for ISO metric threads.

https://www.mcmaster.com/self-tapping-screws/system-of-measurement~metric/screw-size~m6/

Those list use in softer materials ... but I've run across larger sizes of them used in automotive applications. I seem to recall one car that I owned, using M8-ish self-tappers holding the driver and passenger seats down to the floorpan.

 

[J G]

Gentlemen,
I will post a few pictures to explain the product.

The way to construct PEB (Pre Engineered Building) is to first erect a framework :

 

[J G]

... and then fix the cladding on the sides and roof.

 

[J G]

The screw used to fix these is a SElf Drilling Screw :

 

[J G]

Screw in action .................................
The angle thickness here is 5 mm.

 

[J G]

A smaller length screw is used for Valley Fixing ...

 

[J G]

and a longer screw is used for Crest Fixing ...

 

[J G]

Please advise Heat Treatment of this screw in a mesh belt furnace. Bulk.
Material is SAE 1022
C - 0.18 - 0.23
Mn - 0.7 - 1.0
P - 0.04 max
S - 0.05 max

 

[Tmoose]

Industrial Fasteners Institute has some requirements for self-drilling tapping screws. Adapted from SAE apprently.
Design, torque testing, etc.

What is the plating on the screw?
What is your screws' minor diameter, and at what torque value to they break?
I'd be thinking if the torque required to tap exceeds the values in Table 3, the geometry of my screw or maybe even hydrogen embrittlement should be investigated.

 

[botkan]

Hi there
I have read it now, I am doing the heat treatment of self drilling screw the core and surface hardness with the same martial is about 400 Hv and 600 hv

please tell me your temper temperature ? I think you choose wrong temper temperature