harden steel rings

[caboverde]

    Hello, I am a new guest a Dutchman living in Cape Verde. I want to experiment with some steel rings to harden it. It is intended for cylinder head bolts in an aluminum head.

I want to heat the material on charcoal, but then the questions? How long, how warm, what color....etc. And is it actually possible because the steel I don't think has very much carbon.

Best, caboverde.

[Jobtiel1]

Welkom op het forum!

If you add your location to your profile it's easier for us to remember after leaving this post.

If you have spare steel do a test piece, do that first. Heat until it's non-magnetic, and then a little bit more, and quench in vegetable oil, if it doesn't harden then try quenching in water. When it still doesn't harden then the piece is probably not hardenable.

Another option is to do a spark test but you'd have to grind material off to do that.

For the final heat treat you should also normalize, there is plenty of info on the forum for proper procedures on that.

~Jobtiel

[caboverde]

Dank je wel!

    I already turned a piece on the lathe, it's an extension of a fat masonry drill, around 28 mm.
It machined nicely, I'll take it to a blacksmith to see if it works out. After that I will certainly look into it further and buy or make an oven of course.

Nice, on TV I see them making swords and beautiful knives. That's lesson 25 I think just like that. First a few rings.

#Caboverde

[Steve Sells]

be aware its very hard to heat treat an unknown metal correctly

[caboverde]

Thank you Steve,
 That is also my opinion, I am not sure of the type of steel, which is why I first go to the blacksmith for research. The mean problem is, here we don't have good steel. Just for that I will go to Portugal for buy good steel, messink, aluminium.

[caboverde]

    Hi, the first thing I did and tried was to heat up a pan with old frying fat, it started to smoke nicely.
I made the ring super smooth and after a few minutes I shocked it in water, ssstttt...
The material now has a slightly different color and even a file makes little impression, at least?

Would this be a good method to make the surface harder, and maybe someone can explain to me what happened in physics?

Best, caboverde.

[Frazer]

It's probably a translation issue, but when you say you were heating with an old frying vat were you heating the steel rings in a pan with the fryer then you quenched it in water? 

If I'm understanding you correctly, I doubt a frying vat is going to get hot enough to austenitize your steel. As Jobtiel mentioned, use your charcoal to heat the steel until it's no longer magnetic. That transition should happen ~750°C. The color depends on ambient lighting conditions it, but you're looking for a bright red to red-orange color. However, the since the color can be difficult to judge consistently, it's better to have a magnet available and check that way. Then you quench the piece in oil or water.

In your case, you'll probably need to use water since bolts are generally low, sometimes medium, carbon steel.

If you're curious about what's going on in the crystalline structure of the steel during these steps then might be easiest to read something published in your first language. Do a search for pearlite, austenite and martensite.

[caboverde]

    Thanks for explanation, I understand what is meant. Only I have no provision at the moment to wake up a temperature of 700-800 degrees Celsius.

Then I thought about surface hardening! I also cool my drill, which gets very hot, with water, so that it retains its hardness. Then I thought, heat a ring of steel, perhaps Fe42, in a pan with oil on the stove. And then cool down!

Something has to be done of course, the oil will be 250/300 degrees. So the structure on the surface will change due to the cooling of the water.

I don't know if my view is correct, perhaps surface hardening is a better option for washers under head bolts!

All right, caboverde

[LeeJustice]

No.  It will not work like that.  The temperature is much too low.  If you are thinking about hardening ONLY the exterior surface, something like pack carburizing is one way.  However, it also requires the much higher temperature.  There are compounds available like Cherry red which allow you to case harden also.  This method also requires a high heat, like from a torch or forge.

[caboverde]

    Interesting, this brings me to go to a smithy with this knowledge, and explain what the intention is. I just can't generate enough heat at the moment, but I will!

Surface treatment seems to me to be the most appropriate for this application.

I let you know, caboverde.

[Frazer]

Your charcoal can easily reach that temperature in a "Just A Box of Dirt" (JABOD) forge.

Yours doesn't have to look anything like the one above. It depends on your imagination the materials you have on hand... For example, my first forge was the lid from a charcoal barbecue (flipped upside-down to act as a wide bowl), some firebrick, a pipe coming in from the side and a hairdryer. If you don't have firebrick then dirt would've worked just as well, if you don't have a hairdryer then anything that blows air will do. I would still encourage you to speak with a local blacksmith. He will be able to show you his tools and give advise on best practices in your area.

[Charles R. Stevens]

This shows the styles of charcoal forge I know of. 
I find the trench forge 4” wide to be the most efficient. I have melted hard fire bricks and  burnt up steel with one.

[caboverde]

    Hi, it's a pity that someone sees me as a spammer, but it's all about hardening rings.
I did that in this way, the aluminum barrel with sand and heated the ring with a burner.
Red/orange and then in the water.

File test, and the ring seems hard!

Conclusion, the material can be hardened and actually the solution to my problem in this way. I'm going to build a box with sand anyway, it's childishly simple and a nice hobby to tackle some sturdier things.

photo!

[Steve Sells]

Since you didnt understand the warnings you were given let me say it again here, re posting the same thing in more than one place is considered spamming, How can we get you to understand that simple fact?  Posting once is plenty that is all we are trying to tell you.

posting is good.

reposting it again is bad

[Glenn]

If you post the same material multiple times, there is no way to read all the material. 

If you post the material only once, the entire discussion is in one place and all the answers and discussion can be easily followed.

[caboverde]

About the washers!

    My question is that the color of the material when heated with the burner also indicates the temperature of the material at that moment, in this case it is steel.
The color orange, what temperature does it convey?
Blue/purple, I've also seen passing by.

Best, caboverde

[Jobtiel1]

Google a steel temperature colour chart and you'll see some rough estimates of the temperatures of different steel colours.

~Jobtiel

[caboverde]

Red/orange, I think it's enough for my simple washers. But important, because the cylinderhead is alluminium and de torque value for the bolts are 120 N/m.

[Frazer]

Quick question: Why would you need to harden and temper your washers yourself? I think it's safe to assure there are commercially available washers/appropriate cylinder head bolts (that, perhaps, don't require washers) for your engine? This seems like a situation where a $5 part ends up costing you hundreds of dollars on a new cylinder head, engine, etc.

The commercially available washers/bolts will have a much more controlled heat treatment process and reliable specifications.

The blue/purple color you mention is a tempering color. Tempering comes after hardening to release some of the stresses caused by the quench. Tempering colors are easiest to see on bare (freshly ground/sanded) steel.

I'm just going to advise you think twice before you install your washers in a critical application like an engine. If you were just bolting two things together then there isn't much risk, but for your cylinder heads... Do you really trust that you followed the correct process and know material properties you actually need vs think you need? This actually seems like an application where softer washers would be preferred.

[caboverde]

    Quick answer, they are special rings that are not available here, original! 24 x 12.5 x 2mm. Google and even AliExpress don't have these rings! They must be hardened, otherwise the bolt will eat into the material and the tension on the bolt will be released. Incidentally, the coefficient of friction of the bolt and washer must be as low as possible.

Everything you buy here is after market, nothing is original! In this case I think it is better to achieve the best possible result with self-made rings. Tightening once and tightening everything thoroughly after one time should be sufficient.

All right, caboverde

[Glenn]

Without specific application as to make, model, year, etc, there is little we can do to try to locate an OEM part.  Ordering and shipping would then be up to you.

You may want to consider an epoxy to hold tension on the parts.

[caboverde]

Thank you,

 Epoxy, locktite... prevent bolts or nuts from vibrating loose. Good thing to use it there.

The bolts are stretchable, so you have to tighten the bolt with a certain pre-tension. If you do it too loose, the gasket will leak with the known problems.
If you tighten it too much, the bolt may break!

I do it the old school way, tightening to a safe tightening torque. And then after 2500 km, check everything again. That is why it is important which bearing surface the bolt has, with a very low frictional resistance.

It's trial and error, but I'm used to that as an aircraft mechanic who has even worked and flown on the lockheed Neptune.

It's a Nissan Patrol RD28T, 6 cyl. diesel.1990.

[Glenn]

Checking the bolt torque may be engine maintenance, like adding oil, changing the oil, adding fuel when needed, checking tire pressure, or the torque specs on the lug bolts holding the wheels on the vehicle.

[Frazer]

Yes, with torque to yield bolts it's common to torque to certain specification, (sometimes) loosen the bolts, torque them again to some relatively low torque, then turn the bolt a certain number of degrees. The reason an angle is given for the final tightening is to account for friction. The clamping force actually works out to be more repeatable (if you can reliably turn the bolt a certain number of degrees). If you don't have a angle torque wrench then a nominal torque spec is also given (it seems this will be your approach since you give the 120Nm spec).

Of course you already know that about head bolts caboverde, but there may be others that do not.

Assuming everything is torqued correctly then loctite shouldn't be necessary. I expect the heat will degrade it anyway.

Are you sure there were washers on there originally?

Do the old bolts look like this:

or like this:

Both of these come up for that vehicle, although the ones with washers are apparently for the non-turbo version.

If they're like the first image then, assuming they aren't excessively worn/damaged, I'd reuse the old washers (not the bolts, obviously). If it's the second one then I would be surprised if there were washers there in the first place. Regardless I would still reuse the washers before trying to reinvent the wheel.

At the end of the day it's your vehicle and it's a washer so it's easy enough to make. If you're concerned about the increased friction then I would be more worried about the surface finish (polish) of the washer rather than the hardness.

[caboverde]

14 hours ago, Frazer said:

Do the old bolts look like this:

No, that like bolts of Toyota. I have an 4.2 diesel truck and the same bolts for the head and it is steel. The friction is exactly very important, the head is alluminium and need washers.

The second photo that's Nissan, and here all parts are for Toyota. That is the problem.