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Probing The Mysteries Of Metallurgy

Oskar Berendsohn's long career in metallurgy has taken him from the moon to

the courtroom, which demonstrates the wide scope of the profession. Here he

looks at a specimen with a zoom microscope which magnifies up to 60X while

maintaining a reasonably sharp image. -Bee Photo, Zimmermann

B Y A NDREA Z IMMERMANN

Who would dare question the authority of a metallurgist who says he was born

with a silver spoon in his mouth? But after a successful 50-year career in

metallurgy, Oskar Berendsohn finds he is now often grilled about some pretty

hot issues.

That is, at age 71 the Newtown resident is actively consulting and has

recently been an expert witness for court cases trying to prove or refute a

specific cause of fire. For instance, he was asked to examine evidence from an

area thought to be the source of a blaze that killed a million chickens at a

poultry farm. A contractor who installed cable through a conduit was accused

of having nicked the insulation on the wire, thereby creating an environment

for a short that caused the fire.

The metallurgist detected a pinkish residue - different in color than ash

residue - and analyzed this along with other samples from the scene. The

material showed evidence of calcium phosphate or bone residue. Because a

chicken could not have possibly entered the conduit, it was deduced that a rat

was the culprit and the case against the contractor was dropped.

"You look for unusual things that shouldn't be there," said Mr Berendsohn, who

is also a reliability expert. "I used a scanning electro microscope (SEM) -

the most useful tool to metallurgists that has come along in decades with its

infinite depths of field."

The SEM excites things with electrons and because all elements give off

x-rays, you can see a spectrum of elements and this reveals what is present in

the sample, he said. This microscope affords a non-destructive way of

identifying the spectrum, unlike the previous method of carbon emissions which

incinerates the sample. Mr Berendsohn uses specialized lab facility to

carefully study and test materials - "sometimes with the opposition's

metallurgist breathing down my neck."

"I looked for evidence of bone structure, and we found bone platelets," he

said, matter-of-factly. How does a metallurgist know about bone platelets? He

looks for contaminants on various objects, said Mr Berendsohn, and then

consults an atlas on micro-contaminants for identification or confirmation.

There is often so much damage in a fire, all that is left is charred and

burned residue of various descriptions. "One of the few things generally not

destroyed in fire is metal," Mr Berendsohn said. "And the condition of the

metal tells you a lot."

A good example of this is the case of a fatal fire alleged to have been caused

by a kerosene heater. Damage to the heater was so extensive it could not work

- but was it damaged before, during, or after the fire occurred. The product

manufacturer hired Mr Berendsohn to examine the evidence and, hopefully, prove

the heater was not at fault, which he did.

"If metal is molten, it tells you something about the minimum temperature at

the site," he said. "But much more subtle is the micro structure. Fire affects

the 'mosaic' structure of metal."

The pieces of mosaic, irregular in appearance, are referred to as "grains;"

each grain contains thousands of crystals in various arrays. By studying grain

size, distribution, and structure the metallurgist was able to clearly

establish the kerosene heater was not working at the time of the fire and,

therefore, could not have caused it. The grain structure was that of

recrystallized cold worked metal.

Background In Aerospace

It is Mr Berendsohn's education, years of researching, testing, and exploring

the limits of metallurgy - mostly in the aerospace field - that has commanded

the respect of those who now seek him out for his professional assistance.

Until retirement he worked almost exclusively on government projects. He

continues to consult on aerospace projects at Hughes, taking time out for work

on court cases.

A German native, Mr Berendsohn was born into a well-to-do family. But in 1939

things were "so bad" that his father, who was Jewish, decided the family must

leave the country. The US temporarily shut its doors to immigrants so the

family spent the next two years in Honduras, said Mr Berendsohn. They were

then sponsored by a relative in the states and permitted to enter.

"We came over on a banana boat - literally," said Mr Berendsohn. "When we got

here the Depression was still on. It was difficult finding work and

non-citizens could not hold government jobs...If you went on relief you would

be subject to deportation. And if you were forceably deported, you would be

barred forever from coming back into the country."

Although his first job in the US was in an electro-plating shop, he said his

real introduction to metallurgy was later, when he worked at a foundry in

Connecticut making molds and pouring metal.

His education stopped when he left Germany, so he earned his high school

equivalency in the four years he served in the US Army during the Korean War.

Afterwards, he graduated from Brooklyn Polytech Institute with a BS in

metallurgy. Rather than start a foundry, as was his original intent, Mr

Berendsohn decided to apply his skills to a new interest - aerospace.

"A metallurgist, in the simplest sense deals with metals," said Mr Berendsohn.

"Everything from creation (developing from ores), to processing into a

material, to raw plate, to manufacturing processes (heat treatment), and

fabrication processes (welding, forging, rolling, casting), and finishing

(electro-less plating), and sometimes paintings."

The larger the operation, the more specialized a metallurgist would be, he

said. During his 29 years at Perkin Elmer, now Hughes Aircraft, Mr Berendsohn

was one of a very few working in this field at the facility which employed

only 1,000 people. For many years, he was the only metallurgist, which meant

he had a hand in all aspects of the field.

One of the projects he was involved with was an optical alignment device which

allowed Apollo to land correctly on re-entry, and not ricochet off the landing

surface. He also worked on the Hubbell telescope and spent years on a "very

successful," classified government project. As materials engineer for the

telescope project, the metallurgist said he takes great pride in the fact that

there was not a single mechanical failure or wear failure in the telescope.

During his many years spent in the Reliability Department of Perkin Elmer, he

said he wore several hats. "I would specify materials and write

specifications," said the metallurgist. "Another job was to look at

reliability factors - actual and potential failures."

An important aspect of metallurgy is testing materials and parts and analyzing

failures of all types. "Too often decisions and selections of metals and their

process are made without consulting a metallurgist," and this can lead to

failure, said Mr Berendsohn. Design failure is the "worst type because you

have to go back to square one," he said.

The "most treacherous" failure is stress-corrosion, which results in

spontaneous failure, without any apparent cause, without warning and

catastrophically. For instance, this failure occurred on a certain type of

airplane landing gear strut. The problem usually manifests itself with high

strength alloys, and has been little understood until NASA recently compiled

data on materials prone to stress corrosion failure.

Stress corrosion works internally on the metal and does not exhibit brown or

green external spots like other forms of corrosion. It travels along the grain

and breaks the bonds of the mosaic, then the particles let go.

Tests used by the metallurgist to detect possible failure of a part include

x-ray, dye penetrant, acoustic emission, ultra sonic, and high humidity

testing.

Unique Metals

During the time he worked at Perkin Elmer, Mr Berendsohn said he "worked with

some unique metals" including beryllium, which sells for $500/lb, and

titanium. The ratios of strength to weight and stiffness to weight were major

considerations when choosing metals for the structural parts of optics

designed to be used in aerospace.

These are "very, very complex structures" comprised of "all sorts of

additional parts that you would never see on an instrument on the ground,"

said Mr Berendsohn. "They are ultra-precision optics designed to be very

stable under changing conditions [such as temperature]."

During the past ten years he has also been involved with a program at Hughes

that looks at cost effective aspects of and related to metallurgy, such as

material use and machining costs.

"It was marvelous," said Mr Berendsohn, of his experience working on

government projects. "It was superb professional satisfaction."