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hoezap
12-03-2016, 10:57 PM
Hello

Thank you for entering in my post

I read once in a post that only the supplier and the government knows the composition of the Armoured Steel used to machine armored cars for the Ministry of Defense, is that true or there is any way find out the composition of this material

I want to make sure it is really a secret or it can be known

thank you very much in advance for your help

komatias
12-03-2016, 11:54 PM
only the supplier and the government knows the composition of the Armoured Steel used to machine armored cars

You mean manufacture?

Probably the composition is not secret but they are not going to tell you what grade it is. You may find it is some speciality steel that you can buy but they are not going to advertise it as "used to make armoured cars"

hoezap
13-03-2016, 12:20 AM
Yes Manufacture Thank you

Robin Hewitt
13-03-2016, 12:33 AM
Nothing fancy on armoured cars, the good stuff for tanks is a sort of hard soft layer cake. Google Chobham armour for vague details.

What do you want armour plate for?

hoezap
13-03-2016, 01:46 AM
Koromatias may you please tell me the difference between composition of the material and grade of the material, i know the composition indicates all the percenteges of carbon, airon, and any other component, but what do you indicate with a grade?

komatias
13-03-2016, 09:23 AM
Koromatias may you please tell me the difference between composition of the material and grade of the material, i know the composition indicates all the percenteges of carbon, airon, and any other component, but what do you indicate with a grade?


OK so composition just is the mix of materials as you already know. Once you mix them all you can then do lots of different processes to achieve the "Grade". Grade is a very broad term actually. It can encompass many meanings. Post metal processes, material properties, quality, inspection requirements, etc etc.

For example you can heat treat certain metals,(quench, temper) to make them harder. You can cold forge some to to make them stronger.
Quality wise. For example for the same material and heat treat you can accept differing percentage of defects or flaws. There's are usually set out in standards like ISO/Aisi etc. Of course a customer can also set out specifications and requirements and make their own grading system. The supplier would then need to cherry pick the raw material.

So when sellers of various trinkets say aerospace grade titanium it could mean anything. To me it just shows the seller is clueless and probably used the most common grade or whatever was handy. Surgical grade stainless is another one that makes me laugh.

My advice to you if you want to know more about the materials you are working with is to find the suppliers or mills documentation. The datasheets will explain many aspects of the material and grading. If the material is generic and not proprietary you can even look up the corresponding iso or national standard

Robin Hewitt
13-03-2016, 10:40 AM
It's iron man isn't it? You are planning to build a suit.
The tricky bit is the power source :smug:

JAZZCNC
13-03-2016, 11:21 AM
It's iron man isn't it? You are planning to build a suit.
The tricky bit is the power source :smug:

There's no trick to it Robin.? . . . . You can go around any city about 2am and see the Power source of Iron Man.!! . . Beer and kabab..:satellite:

hoezap
13-03-2016, 01:48 PM
Thank you very much for your teaching komatias (http://www.mycncuk.com/members/10154-komatias)

how can you measure the grade of the material and what sort of information can you achieve from it in terms of machining
Thank you very much indeed again for your time

Boyan Silyavski
13-03-2016, 03:54 PM
Nothing is secret:
http://www.texasarmoring.com/armored_vehicle_bulletproofing_materials.html

the steels and grades:
http://web.archive.org/web/20060320134139/http://www.intlsteel.com/PDFs/armor.pdf

JAZZCNC
13-03-2016, 04:33 PM
Nothing is secret:

So who Killed Kennedy and where is Shergar What happened to Lord Lucan.? Whats the composition of Chobham Armour.?

lucan07
13-03-2016, 04:50 PM
Keep it down I am trying to remain anonomous.

hoezap
14-03-2016, 12:39 AM
Thank you very much for the links Boyan Silyavski, however i can see both of your links talk about USA and not UK so may be in UK there are different roles... Thank you very much indeed again for your support

Boyan Silyavski
14-03-2016, 02:57 AM
Thank you very much for the links Boyan Silyavski, however i can see both of your links talk about USA and not UK so may be in UK there are different roles... Thank you very much indeed again for your support


http://www.masteel.co.uk/armour-steel.htm
steel composition


https://www.gov.uk/government/news/new-armour-steel-showcased-at-dsei
look at google for bainite sword, so you will see how its done

most of the steels for one or another reason have been used in knife making/ a broad term which includes swordmaking too/ , so here is a very full interactive table of steels with their chemical properties for reference:
http://zknives.com/knives/steels/steelchart.php

In this world they love to use "super" names but at the end of the day all will be some typical tool steel with sth little changed for added benefit. I looked at the american steel data and more or less it seems typical high carbon steel

komatias
14-03-2016, 08:37 AM
So to answer the question on what numbers to look for when thinking about machining steels:

The yield strength, the elongation and the ultimate tensile strength and the hardness. The higher these numbers the more of a bugger a material is to machine.

What you need to know is the surface speed that works best for a given material, luckily the suppliers will have a good idea what this is so you can find it in their datasheets.

From the surface speeds you can calculate the various other numbers you need.

Plenty of literature on the web and of course cart loads of reference books with the theory of chipping and all the other stuff. I will send you the title of my reference when I get home.