ZDP-189 raises the ante among premier cutting materials ZDP

The
Ferrari
of Blade Steels?
ZDP-189 raises the ante among
premier cutting materials
By Mike Haskew
Matt Conable of William Henry Knives said
ZDP-189 at a Rockwell hardness of 67 Rc is
super-razor sharp. He added that after an
ABS master smith tested the steel, the smith
said, “I don’t know what to make of it. It doesn’t break and it should, it doesn’t chip and it
should, and it’s still shaving sharp.” This is a
close-up of one of the blades in WHK’s Arc
Display System with a ZDP core and 420
stainless exterior.
66 / BLADE
FEBRUARY 2005
William Henry Knives’ Arc Display System—the Blade Magazine 2004 Kitchen Knife Of
The Year® Award winner—boasts paring, utility steak, small chef’s-Santuko and standard
chef’s knives, and a slicer/carver—all with blades of a ZDP core and 22 layers of Mike
Norris damascus on each side. Blade exteriors of 420 stainless are also available.
he search for the ultimate blade steel
never ends, and the likelihood that
one will ever be identified that satisfies every requirement for every manufacturer, custom maker and knife user is slim
at best.
Many factors enter into the blade-steel
equation, including edge-holding capability, ease of sharpening and care, general
availability, cost of purchasing and fabricating, and more. While discussions, testing, and trial and error will continue, some
steels do emerge, separating themselves
from the pack in this category or that.
One of the most recent candidates to
emerge is ZDP-189, manufactured by
Hitachi of Japan.
The mystery surrounding ZDP is paradoxical. It lies in what is both known and
unknown about it. At 20 percent chromium
and 3 percent carbon, it tops just about any
metallurgy chart that can be examined. The
closest in content? It is reportedly in a tie
with a steel called 20-CV for chromium,
T
FEBRUARY 2005
while the 440 series is close at 16-18
percent. As for carbon, CPM 10V is nearest at 2.45 percent. The remainder of ZDP’s
makeup is not readily available. The charts
are simply blank.
Nonetheless, high chromium for stain
resistance and high carbon for edge retention are a dynamic combination. Matt
Conable of William Henry Knives is nothing short of amazed.
“It’s psychotically high in chromium
and carbon, much higher than any of the
standard high-carbon stainlesses,” he
began. “This is not a logical extension of
the family of cutlery steels that are known.
“It’s psychotically
high in chromium
and carbon.”
—Matt Conable
BLADE / 67
exotic
steel
exotic steel
It’s an anomaly and it’s expensive.”
William Henry currently offers ZDP in
a laminate package on its line of kitchen
knives and its Quest folder. (For more on
the Quest, see the December BLADE®.)
According to Conable, the ZDP blades may
indeed redefine expectations of what
household cutlery will do.
“When I decided to pursue the kitchen
line, I went to my friends in Seki, Japan,
and said I wanted to find a studio in Japan
“The edge retention is
phenomenal and the
steel is exotic, but it’s
difficult stuff.”
—Sal Glesser
capable of making the blades William
Henry is known for, and bringing my sense
of aesthetics and quality to kitchen knives,”
Conable continued. “I said, ‘What is the
best blade steel you’ve ever seen? Forget
about price point for now.’”
When ZDP popped up, the Japanese
connection mentioned that a few knives
were being made for the kitchen market
there, and Conable decided to do some testing. The results literally blew him away.
“It does three times what VG will do,”
he said, “four times what D-2 will do if the
D-2 is heat treated perfectly to 62
Rockwell, and when you get into something like the more standard steels like
ATS-34 or 154-CM, we know that it’s [10
times better].”
To compound the mystery, ZDP can be
hardened to an incredible range of about 68
Rc on the Rockwell hardness scale. At that
level, most steels would chip, break or
downright shatter. According to Conable,
though, not ZDP.
“We haven’t been able to prove it any
weaker than the other standard steels,” he
remarked. “In all the tests we’ve done looking for brittleness, we haven’t found ZDP
more susceptible to chipping or breakage in
any way.”
Hitachi Powdered Steel
While knowledge of ZDP itself is not new,
the steel is just now beginning to make
inroads into the knife market. Reportedly, it
is made exclusively in Japan, and Hitachi
will allow only certain vendors to heat treat
it. At press time, Spyderco was working on
a short run of knives with solid ZDP
blades, though the specific model that will
be equipped with the steel has yet to be
determined.
“We first found out about ZDP-189
roughly five years ago,” said Spyderco
president Sal Glesser. “We heard about it as
Hitachi’s new powdered steel. We were
already using U.S. powdered steel, so we
got a piece of it, made a [test model] out of
it, and tested it for edge retention. The
results were quite remarkable. It was up
there with CPM S90V.”
The solid Spyderco blades are to be
used for folders and pocketknives, while
the William Henry kitchen knives employ a
ZDP core with a choice of 420 stainless or
damascus exteriors. A patent is pending on
the resulting ladder-pattern damascus.
“We do not use the ZDP pure for three
reasons,” Conable revealed. “The ZDP is
freakin’ expensive, and it is cheaper to do
the laminate even though there’s cost in
producing it. When you clad the ZDP with
a softer material, you add tensile strength
to the blade, and it is beautiful. When you
take a three-layer steel and grind it, you see
the core following the edge, but it’s inset
about a quarter-inch depending on the
grind. Usually, a hand-rubbed finish is
ZDP Test Results
T
At press time, Spyderco was working on a short run of knives with solid ZDP blades,
though the specific model that will be equipped with the steel has yet to be determined. Meanwhile, the company is offering its Salt 1 (left) and Pacific Salt knives in
blades of H-1 steel, a nitrogen-based rather than a carbon-based alloy.
68 / BLADE
o test ZDP-189, William Henry
Knives sent one of its model B15
folders with the steel to an independent source. According to WHK’s
Rick Thronburg, after 100 cuts
through 1-inch manila rope and with
the edge still cutting well, testing
was concluded. By comparison, here
is how some other steels performed
in the same test:
•440C: 15 cuts;
•154CM: 18 cuts, and;
•D-2: 30 cuts.
“At some point in the future, we
will run the test again to see how far
beyond 100 cuts ZDP can go,” Thronburg noted. “But for now, ZDP-189 so
completely eclipsed the performance
of conventional steels, we had our answer.”—by BLADE® staff
FEBRUARY 2005
uniform but at a different level of
gloss. So, it’s extremely elegant.”
Glesser says that Spyderco
cannot buy ZDP directly. The
company’s
Japanese
maker
purchases it and follows through
with the heat treating. The heattreating process may be just one of
several facts regarding ZDP that
Hitachi holds close.
What do the numbers 189
represent? Glesser said he does
not know. Chances are that few do.
He said that when he asked about
ZDP’s charpy value—a measure
of the dynamic toughness of a
steel—the folks at Hitachi “acted
like they didn’t know what I was
talking about. We couldn’t get a
good translation.”
Higher Prices
The cost associated with ZDP will
result in significantly higher retail
prices for knives with the steel. A
finished folder could run as much
as 50-100 percent more than the
same model in VG-10. William
Henry’s kitchen knives in ZDP are
three-to-four times the price of the
same set in ATS-34.
Why? The answer is relatively simple.
Performance contributes to cost, but
consider the manufacturing process.
“It’s like the Ferrari or Lamborghini of
blade steels,” Glesser offered. “We work
with these high-end steels because we can,
some people want it, and because it’s there.
The edge retention is phenomenal and the
steel is exotic, but it’s difficult stuff. When
you talk about a knife steel, the more obstinate the steel is the better blade it makes
because it doesn’t want to give up molecules of its ‘stuff.’ If you start with a blank
piece of steel, you have to get it to give up
those molecules to make a blade.
“It does three times
what VG will do.”
—Matt Conable
“It takes twice as long to grind a
powdered-steel blade than an ATS-34
blade, and we get half the wheel life. So,
when you start dealing with exotic metals,
that’s why the knives cost more—it’s not
just the price of the steel.
“We haven’t analyzed ZDP yet,” he
continued, “but we probably will in the
future. That might not tell us everything
about what’s in the steel. It’s possible to
mix in certain things that disappear in the
process. They get you from here to there,
but there’s no trace of it after you’re done.”
Widespread use of ZDP is unlikely,
FEBRUARY 2005
Conable said the combination of the
fine edge on each of the blades in
WHK’s Arc Display System—such as
the chef’s/Santuko model—and the ZDP
core with the 420 stainless exterior
makes it extremely easy to sharpen. “If
you haven’t beat the edge up too much,
you can strop it on leather and bring it
back,” he noted.
according to the Spyderco executive, but he
quickly adds that some people do like to
drive Lamborghinis. Spyderco has made
more than one foray into exotic steels and
is offering its Salt 1 and Pacific Salt knives
in blades of H-1, a nitrogen-based rather
than a carbon-based alloy. The Atlantic Salt
will be available in H-1 next year.
William Henry has been experimenting
with folding knives in ZDP for nearly a
year and already has introduced a firstedition run of the Quest model in blades
with the ZDP core and damascus and 420
stainless exteriors. Conable said that more
will follow.
For more information on knives of ZDP
steel, contact William Henry Knives, attn: R.
Thronburg, Dept. BL2, 3200 NE Rivergate,
McMinnville, OR 97128 888.563.4500
www.williamhenryknives.com, or Spyderco,
attn: J. Laituri, Dept. BL2, 820 Spyderco
Way, Golden, CO 80402 800.525.7770
www.spyderco.com.
BLADE / 69