[TheForge] Harden & temper
David E. Smucker
davesmucker at hotmail.com
Thu Jun 16 13:29:12 EDT 2011
All quenching with a water based quenchent above 212 F is based on the
physics of flashing water to steam. For this to be really fast we must
prevent a stable steam film insulating the surface. This is what brine
does, this is what a caustic solution does, this is what "super" quench does
(there is nothing "super" about super quench), this is what high velocity
sprays do. All of the above are very close to twice as fast as still water
with limited movement of the part.
In sheet applications, (continuous web moving in a process line), plain
water sprays are hard to beat on an effective cost bases. If we are making
auto sheet -- there is no other bases than cost.
Dave Smucker
--------------------------------------------------
From: "Bruce Freeman" <freemab222 at gmail.com>
Sent: Thursday, June 16, 2011 12:42 PM
To: "Blacksmithing List Sponsored by ABANA" <theforge at mailman.qth.net>
Subject: Re: [TheForge] Harden & temper
> So, we're comparing a fast-quench of bulk metal to a fast-quench of sheet
> metal.
>
> What if we superquenched sheet metal? Would that be equivalent to
> this new process?
>
> On Thu, Jun 16, 2011 at 12:29 PM, peter fels <artgawk at thegrid.net> wrote:
>> Guessing....This is a sheet metal specific methodology...
>> It's going to be difficult to make those fast temperature shifts on more
>> massive pieces....
>> Though that's where the superquench may come in.
>> The lack of a slow rise and soak is what's interesting.
>> There doesn't seem to be a reference to the hardness achieved.
>> Maybe something for the knife makers?
>>
>> On Jun 16, 2011, at 6:09 AM, Bruce Freeman wrote:
>>
>>> Anyone know how this compares to SuperQuench? I get the impression
>>> they're quite different, but the comparison is obvious.
>>>
>>> On Wed, Jun 15, 2011 at 1:51 PM, peter fels <artgawk at thegrid.net> wrote:
>>>> Neat...looking forward to how it shakes out by the time it gets down to
>>>> us.
>>>>
>>>> On Jun 15, 2011, at 8:20 AM, williamsiron at comcast.net wrote:
>>>>
>>>>>
>>>>>
>>>>> For all you blacksmiths that harden & temper steel. I came across this
>>>>> article and thought you might be interested. The fellow discovered a
>>>>> way to harden/temper steel in about 10 seconds.
>>>>>
>>>>> +++++++++++++++++++++++++++++++++++++++++++
>>>>>
>>>>> Development of rapid heating and cooling (flash processing) process to
>>>>> produce advanced high strength steel microstructures
>>>>>
>>>>>
>>>>>
>>>>> Authors: Lolla, T; Cola, G; Narayanan, B; Alexandrov, B; Babu, S S
>>>>>
>>>>>
>>>>>
>>>>> Source: Materials Science and Technology , Volume 27, Number 5, May
>>>>> 2011 , pp. 863-875
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Top of Form
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Bottom of Form
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Abstract:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Flash processing of an AISI8620 steel sheet, which involves rapid
>>>>> heating and cooling with an overall process duration of <10 s,
>>>>> produced a steel microstructure with a high tensile strength and good
>>>>> ductility similar to that of advanced high strength steels. Flash
>>>>> processed steel [ultimate tensile strength (UTS): 1694 MPa,
>>>>> elongation: 7·1%], showed at least 7% higher UTS and 30% greater
>>>>> elongation than published results on martensitic advanced high
>>>>> strength steel (UTS: 1585 MPa, elongation: 5·1%). The underlying
>>>>> microstructure was characterised with optical, scanning electron,
>>>>> transmission electron microscopy as well as hardness mapping. A
>>>>> complex distribution of bainitic and martensite microstructures with
>>>>> carbides was observed. A mechanism for the above microstructure
>>>>> evolution is proposed.
>>>>>
>>>>>
>>>>>
>>>>> Articles that cite this article?
>>>>>
>>>>>
>>>>>
>>>>> Keywords: Flash processing ; Phase transformation ; Bainite ;
>>>>> Microstructure characterisation ; Advanced high strength steels ; Heat
>>>>> treatment
>>>>>
>>>>>
>>>>>
>>>>> Document Type: Original Article
>>>>>
>>>>>
>>>>>
>>>>> DOI: 10.1179/174328409X433813
>>>>>
>>>>>
>>>>>
>>>>> A Detroit entrepreneur surprised engineers at Ohio State University
>>>>> recently when he invented a heat-treatment that makes steel 7 percent
>>>>> stronger than any steel on record – in less than 10 seconds.
>>>>>
>>>>> In fact, the steel, now trademarked as Flash Bainite , has tested
>>>>> stronger and more shock-absorbing than the most common titanium alloys
>>>>> used by industry.
>>>>>
>>>>> Now the entrepreneur is working with researchers at Ohio State
>>>>> University to better understand the science behind the new treatment,
>>>>> called flash processing.
>>>>>
>>>>> What they’ve discovered may hold the key to making cars and military
>>>>> vehicles lighter, stronger, and more fuel-efficient.
>>>>>
>>>>> In the current issue of the journal Materials Science and Technology ,
>>>>> the inventor and his Ohio State partners describe how rapidly heating
>>>>> and cooling steel sheets changes the microstructure inside the alloy
>>>>> to make it stronger and less brittle.
>>>>>
>>>>> The basic process of heat-treating steel has changed little in the
>>>>> modern age, and engineer Suresh Babu is one of few researchers
>>>>> worldwide who still study how to tune the properties of steel in
>>>>> detail. He’s an associate professor of materials science and
>>>>> engineering at Ohio State, and Director of the National Science
>>>>> Foundation (NSF) Center for Integrative Materials Joining for Energy
>>>>> Applications, headquartered at the university.
>>>>>
>>>>> “Steel is what we would call a ‘mature technology.’ We’d like to think
>>>>> we know most everything about it,” he said. “If someone invented a way
>>>>> to strengthen the strongest steels even a few percent, that would be a
>>>>> big deal. But 7 percent? That’s huge.”
>>>>>
>>>>> Yet, when inventor Gary Cola initially approached him, Babu didn’t
>>>>> know what to think.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> “The process that Gary described – it shouldn’t have worked,” he said.
>>>>> “I didn’t believe him. So he took my students and me to Detroit.”
>>>>>
>>>>> Cola showed them his proprietary lab setup at SFP Works, LLC., where
>>>>> rollers carried steel sheets through flames as hot as 1100 degrees
>>>>> Celsius and then into a cooling liquid bath.
>>>>>
>>>>>
>>>>>
>>>>> Though the typical temperature and length of time for hardening varies
>>>>> by industry, most steels are heat-treated at around 900 degrees
>>>>> Celsius for a few hours. Others are heated at similar temperatures for
>>>>> days.
>>>>>
>>>>> Cola’s entire process took less than 10 seconds.
>>>>>
>>>>> He claimed that the resulting steel was 7 percent stronger than
>>>>> martensitic advanced high-strength steel. [Martensitic steel is so
>>>>> named because the internal microstructure is entirely composed of a
>>>>> crystal form called martensite.] Cola further claimed that his steel
>>>>> could be drawn – that is, thinned and lengthened – 30 percent more
>>>>> than martensitic steels without losing its enhanced strength.
>>>>>
>>>>> If that were true, then Cola’s steel could enable carmakers to build
>>>>> frames that are up to 30 percent thinner and lighter without
>>>>> compromising safety. Or, it could reinforce an armored vehicle without
>>>>> weighing it down.
>>>>>
>>>>> “We asked for a few samples to test, and it turned out that everything
>>>>> he said was true,” said Ohio State graduate student Tapasvi Lolla.
>>>>> “Then it was up to us to understand what was happening.”
>>>>>
>>>>> Cola is a self-taught metallurgist, and he wanted help from Babu and
>>>>> his team to reveal the physics behind the process – to understand it
>>>>> in detail so that he could find ways to adapt it and even improve it.
>>>>>
>>>>> He partnered with Ohio State to provide research support for Brian
>>>>> Hanhold, who was an undergraduate student at the time, and Lolla, who
>>>>> subsequently earned his master’s degree working out the answer.
>>>>>
>>>>> Using an electron microscope, they discovered that Cola’s process did
>>>>> indeed form martensite microstructure inside the steel. But they also
>>>>> saw another form called bainite microstructure, scattered with
>>>>> carbon-rich compounds called carbides.
>>>>>
>>>>> In traditional, slow heat treatments, steel’s initial microstructure
>>>>> always dissolves into a homogeneous phase called austenite at peak
>>>>> temperature, Babu explained. But as the steel cools rapidly from this
>>>>> high temperature, all of the austenite normally transforms into
>>>>> martensite.
>>>>>
>>>>>
>>>>>
>>>>> “We think that, because this new process is so fast with rapid heating
>>>>> and cooling, the carbides don’t get a chance to dissolve completely
>>>>> within austenite at high temperature, so they remain in the steel and
>>>>> make this unique microstructure containing bainite, martensite and
>>>>> carbides,” Babu said.
>>>>>
>>>>> Lolla pointed out that this unique microstructure boosts ductility --
>>>>> meaning that the steel can crumple a great deal before breaking –
>>>>> making it a potential impact-absorber for automotive applications.
>>>>>
>>>>> Babu, Lolla, Ohio State research scientist Boian Alexandrov, and Cola
>>>>> co-authored the paper with Badri Narayanan, a doctoral student in
>>>>> materials science and engineering.
>>>>>
>>>>> Now Hanhold is working to carry over his lessons into welding
>>>>> engineering, where he hopes to solve the problem of heat-induced
>>>>> weakening during welding. High-strength steel often weakens just
>>>>> outside the weld joint, where the alloy has been heated and cooled.
>>>>> Hanhold suspects that bringing the speed of Cola’s method to welding
>>>>> might minimize the damage to adjacent areas and reduce the weakening.
>>>>>
>>>>> If he succeeds, his discovery will benefit industrial partners of the
>>>>> NSF Center for Integrative Materials Joining Science for Energy
>>>>> Applications, which formed earlier this year. Ohio State’s academic
>>>>> partners on the center include Lehigh University, the University of
>>>>> Wisconsin-Madison, and the Colorado School of Mines.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
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>>>
>>>
>>>
>>> --
>>> Bruce
>>> NJ
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>
>
>
> --
> Bruce
> NJ
> ______________________________________________________________
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