Martensite or High Carbon Steel?

If I have understood your question correctly you mean by "martinsite" a carbon steel that has been heat treated to give a martinsitic structure. If that is the case I am surprised that you can form the material at all. Steel with an un-tempered martinsitic structure will be very hard (over 60 Rockwell C) and have virtually no malleability or ductility and is therefore likely to crack or shatter when you try to form it.

The short answer to your question is Yes, but you say that you are using strip material which may pose a problem. In theory you could cut and form your parts from a fully normalised (softened) high carbon strip and then heat treat it to give the desired properties. Martinsite is a highly stressed structure and it is likely that your parts will bend and distort during any heat treatment so great care is needed when handling thin sections.

In any event, after hardening the parts will need to be tempered. A tempered martinsite structure will still have the degree of hardness required, but will now have some degree of toughness.

I do not know your application, but you may consider using a "mild" steel for you fabrication and have the parts carburised or carbonitrided. This will give you a hard "skin" with a tough core which should be better able to resist fracture.

Hope this helps.

They sell a steel called martinsite at different steel suppliers it has a tensile strength of 130,000 to 220,000 pounds per square inch and you can get it between 41 to 47 C Rockwell.We would use a tensile strength of 130,000 for our application on .050 thousandths of an inch thick material by 2.5 inches strip. Thank you for your answer it does help i will bring a part to a heat treat house and hopefully see which of the two processes would be best.

You are going to be incredibly disappointed be cause the way the heat treatment works is by transforming the carbon into martensite.

You can get slightly lower hardness tensile by tempering back the already heat treated martensitic steel, but heat treated = martensite unless heattreated = anneal, in that case, you won't have strength.

milo

Thanks Milo but im trying to get away from using the prehardened material and use a soft annealed material then heat treat the steel and get the same results in the end

You may want to consider using Dual Phase Material. One source that we use is SSAB Swedish Steel. They have varying grades to choose from depending on your requirements Dolcol 115 DP has up to 9% elongation for forming and requires only a one metal thickness minimum bend radius and has 115 to 130 ksi tensile after a low temperature (338 degrees F) for 20 minutes heat treat and Docal 140 DP has 140 to 170 ksi tensile after a 340 degree F 20 minute heat treat, however it only has 8% elongation and requires a 3 times metal thickness bend radius. There are other Dual Phase suppliers, but I don't have their spec sheets handy.

Either Martensitic SS AISI410>>>

OR Swedish Steel:

Statistics (ktonnes unless otherwise stated) 2002 2003 2004 2005 2006 Production of crude steel in the group 3 881 3 911 4 142 3 966 3 737 Production of slabs in the group 3 661 3 620 3 834 3 642 3 413 Production of hot rolled steel sheet and plate 3 257 3 286 3 284 3 072 3 246 - Division Sheet 2 675 2 640 2 633 2 440 2 660 - Division Heavy Plate 582 646 651 632 586 Shipments in the Steel Operation 3 113 3 130 3 187 2 972 3 096 - Division Sheet 2 538 2 480 2 492 2 311 2 474 - Division Heavy Plate 575 650 695 661 622 Shipments of core niche products 594 697 893 978 1 209 - EHS/UHS 278 331 447 507 699 - Quenched & Tempered heavy plate 316 366 447 471 510 Core niche products as % of total shipments in the steel operation 19 22 28 33 39 EHS/UHS as % of total steel sheet shipments 11 13 18 22 28 Quenched & tempered heavy plate as % of total plate shipments

Ask for Details at

Box 26208, SE-100 40 STOCKHOLM
Phone: int. +46 8 45 45 700
Fax: Int. +46 8 45 45 725
E-mail: info@ssab.se

This recommendation to go with stainless steel is based on????

The swedish production statistics tell us what???

milo

*1 The Original Q was

<.The costumer requested martinsite strip material to make the parts but he is flexibly>

So form annealed-easy on your machines-and harden -temper to his need. And he gets Martensitic(maybe Nickel-free cheap Stainless)

*2 The Swedish Steel :Again (almost) No-Nickel-Stainless is catching on .And Going Places. A fine Martensitic High Strength Stainless at prices not much higher than plain Carbon -non-Martensitic steels.Mostly supplied in strips (he wants strips).

O-kay.

milo

Milo ,it is not O-kAY I know.

Your previous post lucidly explains the Crystallographic redistributions resulting in Martensite.And how not to mix up Carbon- to -Carbide redistribution...

But look at this:Thanks Milo but im trying to get away from using the prehardened material and use a soft annealed material then heat treat the steel and get the same results in the end.

He can not get the same result in the end! Trying In Vain!

Does his customer want guaranteed extreme strengths?

Then do not talk about Martensite again.

Go to SSAB site-get fully engrossed and pick the very best. Forget about YOUR HEAT TREATING. Bend/cut/weld/machine and use. Do not apply fire (as you said)again !

I absolutely agree with you MUKULMAHANT.

On this forum we really seem to be limited by our joint ability to use english language.

Repeatably.

I'd love to see the cost analysis for this project.

I'm Off to the sacred grill to apply fire to the marinated sacred cow of 87% Lean.

Enjoy your evening.

milo

Just for clarity, untempered martinsite is the condition of the steel after heat treatment. For high carbon steel, the carbon content is generally over 1%. Steel is formed of an iron matrix with carbon as well as other alloying materials. The carbon is transformed to carbides by heat to form untempered martinsite. As another writer noted, this untempered martinsite is very hard and brittle. Doing this required a high carbon steel that is heated to the transformation temperature, which is different for each steel type, and then quenched. The steel is then re-heated and "drawn back" to tempered condition which is softer and less brittle. Cold forming high carbon steels will cold work the steel, which will harden the steel. You may have to anneal the steel to bring it back to a "soft" condition to continue processing. Whether or not you will need to do this will depend on how complex the forming process is. The final part will have included stresses and may distort during heat treating. Annealing the part prior to final heat treatment may be required to return the product to a soft and unstressed condition. Hope this helps.

"The carbon is transformed to carbides by heat to form untempered martinsite."

Carbon is not transformed to carbides by heat to form untempered martensite.

Not to put too fine a point on it, but 'Martensite' describes the acicular (needle like) microstructure formed by the diffusionless phase transformation where the parent and product phases have a specific relationship crystallographically (not chemically!). This diffusionless process occurs upon quenching from the austenitic phase. Thus martensite describes a microstructure.

'Carbide' describes a chemical compound of carbon conatining one or more metallic elements, ie chrome carbide, vanadium carbide etc.. Martensite is not correctly described as a carbide.

Therefore, Carbon is not transformed to carbides by heat to form untempered martensite.

Austenite is transformed to martensite by rapid cooling between the Ms and Mf temperatures. Austenite is formed by heating the room temperature steel with its multiple phases (ferrite and cementite) above the Ac1 temperature, by the time it is at the the Ac3 temperature all ferrite will have been transformed into austenite. This is all a function of solubility.

It is the rapid quenching of austenite that induces the diffusionless phase transformation described above into the martensitic microstructure. This phase is not really stable, and it is decomposed by heat (tempering) into more stable distributions of ferrite and pearlite (hypoeutectoid compositions), or cementite and pearlite (hypereutectoid compositions). However, the tempering process does not at first decompose the martensite, it allows the stress es contained t be relieved.

Cold forming the high carbon steel will indeed cause workhardening and distortion. we are not certain that an anneal prior to heat treatment will do anything for you other than possibly decarburize the surface of your material, making full hardness difficult to achieve. But I know that when it comes to steel, most people love to apply fire...

Why not keep it simple?

milo

A threat that everyone perceives and no one discusses hurts a company more than a threat that is clearly revealed-Tracy Goss

Thanks for the additional in-sight

paul horgan

No problem, you had good pragmatic understanding and descriptions of results, but I thought that the mechanism needed to be more precise.

Thats the joy of a free market of ideas forum. Its self correcting nature makes it a better place for all of us.

milo