Thread: Coil spring steel crumbling

I had contacted a few of you guys via PM about a problem I had, but didn't have any pics at the time. My original query was:

I have access to these springs from the railroad that are basically a coil spring. I cut several rings, straightened them, and proceeded to beat them to submission. Man this stuff is tough to work, cold O-1 is softer. My problem is that once I have drawn out the coils, I am finding a lot of fractures, I'm talking about a LOT. Too much to even consider making a knife, much less a razor out of it. My question is, what causes such a thing? Bad steel? I'll get some pics tomorrow & try to post them on the forum.
Thanks,
Scott

I decided to go ahead with a piece that I had hammered out and took it to the grinder for a rough grind, heated it to non-magnetic & let it cool to black, heated it to non-magnetic and let it soak for 10 minutes, quenched in canola oil, tempered in oven at 375F for 1 hour, let cool to room temp.

I did a rough finish grind, never letting it get hotter than my fingers could handle just like any knife or razor, and took it to my DMT11C. The edge literally will crumble away once it gets close to a bevel set.

When I was working it, I will admit that there were times that I would let it get to "red" as I was working it as this stuff is SOOOO hard, annealed O-1 is literally twice as soft at room temp!

Here's some pics, notice the rough handle and some pics show fractures in the grind:

Mike Blue???????

How hot are you taking it before hammering? It seems you may be way to cool...

At times near welding temps

Annealed/normalized prior? Just typing out loud here... I know some steels need to be near welding temps, no big blows, and no big temp drops, as in a narrow working window. Old spring steel shouldn't be exotic, something similar to 5160.

For example A copy paste from a web resource.

5160 steel spec's and heat treating
from the ASM manual:

5160, 5160H, 5160RH

5160 AISI 5160H AISI
Carbon 0.56 to 0.64 Carbon 0.55 to 0.65
Manganese 0.75 to 1.00 Manganese 0.65 to 1.00
Phosphorus 0.035 Max Silicon 0.15 to 0.35
Sulfur 0.040 Max Chromium 0.60 to 1.00
Silicon 0.15 to 0.30
Chromium 0.70 to 0.90

5160RH AISI
Carbon 0.56 to 0.64
Manganese 0.75 to 1.00
Silicon 0.15 to 0.35
Chromium 0.70 to 0.90

Considered a high-carbon alloy steel. As quenched hardness of 58 to 63 HRC. Used for a variety of spring
applications, notably flat springs. Often uses Austempering as a method of heat-treating.

Forging max heat 2200 degrees F.
Do not forge below 1600 degrees F.

Normalizing - heat to 1600 F and cool in air.

Annealing – for predominately pearlite structure heat to 1525 F cool rapidly to 1300 F then cool to 1200 F at a rate
not to exceed 20 F per hour – or, heat to 1525 F cool rapidly to 1245 F and hold for 6 hours.

For predominately spheroidized structure heat to 1380 F cool rapidly to 1300 F then cool to 1200 F at a rate not to
exceed 10 F per hour – or, heat to 1380 F cool rapidly to 1245 F and hold for 10 hours.

Hardening – austenitize at 1525 F and quench in oil or polymer. Gas nitriding and ion nitriding are suitable processes.

Austempering - austenitize at 1555 F and quench in molten salt bath at 600 F. Hold for one hour, cool in air, needs no tempering, approximately 46 to 52 HRC is obtained

I'm adding this because the above was writen for tool / spring steel use.
52 is low for a knife
lower molten salt bath to about 400 - 450 F
depending on the use of the knife.

Patent info for high strength steel railroad springs

What is claimed is:

1. A high strength spring of steel having the following composition by weight:

carbon: 0.6 to 0.7%

silicon: 1.2 to 1.6%

Manganese: 0.5 to 0.8%

Chromium: 0.5 to 0.8%

0.05 to 0.2% of at least one of the group consisting of vanadium, molybdenum, niobium and tantalum, the remainder being iron and inevitable impurities, and

non-metallic inclusions having maximum particle size equal to or smaller than 15 .mu.m;

the spring having been applied with a residual compression stress at a portion adjacent the outer surface thereof in such a way that the maximum of said residual compression stress ranges from 85 to 110 kgf/mm.sup.2, and wherein

the spring has a surface roughness equal to or smaller than 15 .mu.m.

2. The high strength spring as set forth in claim 1, wherein said surface roughness ranges from 5 to 15 .mu.m.

3. The high strength spring as set forth in claim 1, wherein the steel is formed of wire having a reduction of area equal to or larger than 40%.

4. A method of producing a high strength spring, comprising the steps of:

preparing steel of a composition which consists essentially of 0.6 to 0.7 wt % of carbon 1.2 to 1.6 wt % silicon, 0.5 to 0.8 wt % of manganese, 0.5 to 0.8 wt % of chromium, 0.05 to 0.2 wt % in total of at least one of vanadium, molybdenum, niobium and tantalam, and the balance of iron and inevitable impurities, and maximum particle size of non-metallic inclusions being limited so as to be equal to or smaller than 15 .mu.m;

forming a spring from said steel;

applying a residual compression stress adjacent the outer surface of said spring in such a manner that the maximum of said residual compression stress ranges from 85 to 110 kgf/mm.sup.2 ; and

processing said spring in such a way that the surface roughness is equal to or smaller than 15 .mu.m.

5. The method as set forth in claim 4 wherein said surface roughness ranges from 5 to 15 .mu.m.

6. The method as set forth in claim 5 wherein said steel is wire and has a reduction of area that is equal to or larger than 40%.

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The steels are similar enough, that the listed forging temps in the above post, should be considered as a working window. That might help you, also dont try to move it to fast. easy does it. Hope this all helps.

Originally Posted by shooter74743

At times near welding temps

It's the other times I'm worrying about

This was a "helper" spring that fits inside of the big coil spring, so I will try the actual big coil spring after I get my propane bottles filled.

I contacted several of you guys via PM before I posted the pics who I know a bit and their responses lead me to believe two things: I may/probably worked it when it was too cool, I've been beating it to death (really using a lot of force instead the weight of the hammer), their most likely was micro fractures that I just made worse, and the steel may not be such a good steel like the old car springs that were made of 5160. One of my mentor's stated: That stuff may be a 8xxx or 9xxx series steel. Maybe a high sulfur material.

I'm not going to count it off as a total failure...I had fun for my first time at the anvil and really hot steel. I'm deeply concerned about one thing though...I REALLY liked it...trying to figure out how to pipe some of the natural gas that's piped to the house to my working area without breaking the bank.

Last thing is a note to self and something to give you guys a chuckle. While I was working the steel, using the more rounded end of my hammer tapering the blade above to a thinner edge, I missed the steel and hit just the anvil. Talk about a wake-up call. I am really amazed how fast that hammer can come sailing at your head! Obviously my borrowed anvil has "plenty" rebound!