Author Topic: What is LW-50 rifle barrel steel? (Read 2166 times)

Naphtali · « **on:** February 10, 2004, 06:41:04 AM »

Moderator: I'm not sure I put this query in the correct category. If you think it should be moved for me to obtain an answer, please do so.
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I need a chemical analysis, specifications sheet, or a corrosion resistance comparative analysis of a proprietary German stainless barrel steel with 416R/416BQ and 17-4PH steels.

Lothar Walther GmbH is a German rifle barrel manufacturer. The company uses a proprietary steel LW-50 (I've seen it identified as LW-50, LW 50, and Lothar Walther 50.) The claim is that it is "truly stainless" rather than moderately corrosion resistant as is 410 series stainless steels.

Excluding advertising hyperbole, I cannot find any hard data about the steel.

PaulS · « **Reply #1 on:** February 10, 2004, 09:42:36 AM »

I think you will get more attention and better answers in the Gunsmithing forum. I have moved it there.

PaulS

gunnut69 · « **Reply #2 on:** February 10, 2004, 07:30:37 PM »

Boy that is truly a good question. If it is truly proprietery the analysis may be confidential. I find it unlikely that such a steel would be hard enough to resist the abrasion of high velocity bullets and not contain enough carbon to be a stain resistant steel (i.e. the 410 series). I am not a metalurgist but will attempt to make a few inquiries to some who may have such knowledge. If you should find an answer somewhere before I can I would appreciate you posting it here for our benefit also. Also where did you find reference to this material??

Naphtali · « **Reply #3 on:** February 11, 2004, 03:47:20 AM »

gunnut69:

How I found the information is by way of a series of Sherlock 2 searches (Macintosh OS search engine built into the OS) followed by a Google search.

I remembered a proprietary barrel ID finish DURABORE from BlackStar from the middle 1990s. To make a long story less long, it was a solution carbon nitride. But it had a severe affinity for turning carbon in the bore into concrete.

I visited BlackStar's web site to find DURABORE was no longer offered, and the company had changed vendors for their rifled barrel blanks. I read everything in the web site carefully and found two sentences buried in a testimonial/infomercial that stated the new barrels were "truly stainless."

I then did more searching to find many vendors use these barrels. Lothar Walther's web site has no quantitative analysis or comparison available.

Without correct steel nomenclature, ASME, AISI, DIN, WN #s cannot be cross referenced to identify LW 50. I have several additional requests for information out in the Ether.

On it's face I tend to agree "if it sounds too good to be true, it probably is." But I know that Obermeyer has made barrels of titanium alloy and 17-4PH -- both for the military, both not very successful. And these were decades ago. So why should not modern technology allow the use of, for example, martensitic steels similar to AISI 431, an order of magnitude more stain resistant than 410 series steels?
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One last thing, you mention "abrasion resistance of high velocity bullets" as being THE significant cause of barrel wear. Nope, t'ain't so. Heat erosion is the essential wear factor. The heating of ID's surface for microseconds during combustion changes heat treat on that surface. Over time, surface steel flakes and crumbles (microscopically) to create a moonscape of microscopic fissures, cracks, roughness. Eventually, erosion changes ID dimensions beginning at throat.

Abrasion may be A factor in loss of accuracy and barrel life, but it is insignificant in the grand scheme of things compared with heat erosion.

So we look for steels that better withstand this, and the products of black powder combustion if muzzleloading, when we want more durable barrels.
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OK, let's find a chemical analysis for LW 50.

John Traveler · « **Reply #4 on:** February 11, 2004, 04:42:29 AM »

Napthali,

From my limited perspective and understanding of metalurgy, I have to agree with you that heat is the main cause of barrel erosion, and not projectile friction.

I had occasion to observe borescope and wear gage analysis of 25mm auto cannon barrels with the Canadian Army a couple years back. These were for several factory-new cannon barrels used in the Bushmaster automatic cannons in their then-new armoured vehicle turrets. Rounds fired were carefully documented for each weapon/barrel set.

The barrel throats looked like dried, cracked, crazed leather after less than 1,000 rounds each. Imagine those photographs of drought-dried mud lake bottoms of equatorial Africa or Australia...that's what the first several inches of the barrel throats looked like! I can only think that the HUGE powder charge of the 25mm NATO ammunition and their practise of firing in three-round bursts caused this. Those over-heated barrels started wearing out prematurely from barrel overheating!

I will be attending the SHOT show this weekend, and will ask the Lothar-Walther folks if they know anything about the special steel.

John

savageT · « **Reply #5 on:** February 11, 2004, 06:07:31 AM »

Napthali,
I understand what you want to do for analysis and as long as you understand the cost involved, I will furnish you with an independant laboratory to do the testing for you here in Central NY (Ithaca):

IMR Test Labs
Division of Ithaca Materials Research & Testing Inc.
1.888.464.8422
fax 607.533.9210
Email: imr@imrtest.com

Jim

Naphtali · « **Reply #6 on:** February 11, 2004, 06:22:10 AM »

savageT:

Many thanks for your response. You may be putting the cart in front of the horse, though.

LW 50 barrels are between 250 and "name a number" dollars. The purpose for my query is not to test a barrel I've purchased, but to be able to judge what I should expect from an LW 50 barrel, should I choose to buy, BEFORE I invest several hundred dollars.

Since my main interests in these barrels are corrosion resistance to acids and residue from black powder combustion, chemical specifications will yield reasonably accurate indicators. Carpenter Technology makes these analyses available in their Stainless Steels Selection Handbooks. The information changes from book to book. But if you hunt for it, you find it. And Carpenter's data supply the baseline from which to judge.

If LW 50's advantage is more hyperbole than chemistry, I can avoid spending perhaps 1200 dollars for four rifle barrels when I buy Green Mountain or other barrels of less exotic, less expensively advertised materials.

Boy, did I take the long way around to say I'm tight with a buck.

Will52100 · « **Reply #7 on:** February 11, 2004, 06:46:03 PM »

Nothing to add realy, except to say that if they say they have a secret steel, they are full of crap.

For about 50$ you can get a spectrograph of just about any steel you want from Cruciable by sending them a sample. It may not be 100% acurate, but will give you a very good idea of the compisition.

With services like that there are no secret steel forula's. There may be secrect ways of manipulating the steel, but not the steel itself.

The most stain resitant alloy I know of that is hardnable is 440C with over 2% Cr. The new CPM steels are suposed to be better, but I have no experiance with them. Basicly the higher the Cr. content the more stainless a steel is, but the weeker it is due to larger grain structure. Anything over 13% is considered stainless by industry standards.

One thing on stainless, on martensitic stainless if it's not heat treated it's not stainless. For the stainless to exibit stainless properties it has to be hardened. It can then be tempered back a good bit. You may aready know this, I have no idea how rifle barrels are heat treated if they are even heat treated.

I just get irritated when some outfit says they have a secret steel that no one else has or can find out, if any one else realy wanted to know what it was they can find out.

Naphtali · « **Reply #8 on:** February 12, 2004, 05:48:48 AM »

Will52100:

Let's try to keep discussion from the gutter.

Had you read what I wrote you would have apprehended:

1. I called it a proprietary steel. Lothar Walther has not. I did not quote them. They refer to it as new.

2. Until or unless we have negatively identified the steel as not having a DIN/WN #, or other standard, we know nothing more than I have written.

3. Is 17-4PH that is called CARPENTER CUSTOM 630, and AISI 630, and UNS S17400 a proprietary steel because it is known by more than one name or designation? Of course not.

4. "The most stain resitant alloy I know of that is hardnable is 440C with over 2% Cr. The new CPM steels are suposed to be better, but I have no experiance with them. Basicly the higher the Cr. content the more stainless a steel is, but the weeker it is due to larger grain structure. Anything over 13% is considered stainless by industry standards."

While you write the truth of your knowledge, let's just leave this as incomplete knowledge.

Please people, let's work the problem. If we find an answer, we may all benefit.

Will52100 · « **Reply #9 on:** February 12, 2004, 06:01:56 AM »

Point taken Naphtali, I meant no disrespect to anyone here, and apoligize if I offended anyone.