Ken - Now the real problem is identified! Very common these days.
First, Mn-Si killed steels without Al are prevalent for long product billet cast products where open stream metering nozzle casting is used. Al is problematic in those cases. In slab cast products with SEN's, Al additions are common, almost universal.
If the spec was written many years ago, the product was probably ingot cast. A 0.10% max Si would suggest a semi-killed ingot casting process. The purpose of semi-killed was to maximize steel yield, minimizing the normal center line "pipe" that occurred on fully killed ingot cast steels and must be discarded. But semi-killed steels were never "B" steels.
Now you are asking for a 86B30 steel. Boron steels normally have Al added to deoxidize the steel sufficiently to protect the Ti from oxidation, allowing the Ti to tie up the N, so that the B will work for hardenability and not form BN. Al is required because the Si, even at normal levels up to 0.35%, is not a strong enough deoxidizer to protect the Ti. But there is no obvious reason for restricting the Si level unless it is for scaling or plating/coating reasons. Even if ingot cast, the steel will have to be fully killed to allow the B to work. If you don't have Al and Ti contents stated in the mill cert, i would question whether you have a B grade.
Bob Glodowski
RJG Metallurgical LLC
bobglodowski@rjgmet.com------------------------------
Robert Glodowski
RJG Metallurgical LLC,Stratcor Incorporated
Gibsonia PA
(412) 680-3308
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Original Message:
Sent: 03-21-2022 11:43
From: Ken Kirby
Subject: Silicon level of alloy steel
The specification comes from within my company, but it was written a long time ago and there is disagreement about the need or benefit, if any, of the silicon restriction.
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Ken Kirby
Snap-on, Inc.
Kenosha WI
(262) 748-3836
Original Message:
Sent: 03-20-2022 13:44
From: Edward Szekeres
Subject: Silicon level of alloy steel
Ken Kirby asked 2 questions. Paraphrasing:
- …. the purpose of specifying that an alloy steel (86B30?) has 0.10% max silicon….
- ….is Al required to insure a fully-killed steel..?
It seems to me, that if someone is specifying an element content outside of the normal range, you would ask that person, or organization, to explain the reason for the request, not try to assume a reasoning.
Ken's second question has to do with steelmaking. As all metallurgist know, the chemistry of a steel alloy is made in a batch of liquid. Each batch of liquid steel must be converted into a solid. In modern steelmaking, this conversion is done in a continuous casting machine (caster). Continuous casting has replaced virtually 99% of ingot casting, the previous technology. Gone are the days of ingot-cast un-deoxidized rimmed steel, which accounted for well over 50% of steel produced in North America prior to 1970. All steel solidified in a continuous caster must be deoxidized, and Al is a de-oxidizing element used in most cases (steel for tire-cord wire is one exception). Ken, if you run a check analysis on a sample of the 86B30 you are using, and ask for soluble-Al, I would be surprised if it is less than 0.015%.
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Edward Szekeres
Consultant
Utica NY
(585) 766-3536
Original Message:
Sent: 03-18-2022 10:19
From: Ken Kirby
Subject: Silicon level of alloy steel
What would be the purpose of specifying that an alloy steel has 0.10% max silicon, as opposed to 0.15%-0.35% silicon? Is an additional deoxidizer such as aluminum required to fully kill the steel with the lower silicon level?
I'm specifically working with 86B30 for cold forming.
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Ken Kirby
Kenosha WI
(262) 748-3836
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