Do special finishes make sense for stainless steel?

Yes. Electropolishing of stainless steel is commonly used for food, drug, medical and semi-conductor applications and for those where high fatigue strength is needed. It removes burrs and sharp edges and lessens strains by removing microscopic nicks from the surface.

Sources: Professor Roger Wright of Rensselaer Polytechnic Institute; Dr. Jack Grubb of Allegheny Ludlum; Dr. William H. Cullen Jr. of the Nuclear Regulatory Commission and Dr. Shui Lee of Central Wire Industries; websites of AK Steel, Allegheny Technologies, Carpenter Technology, Sandmeyer Steel and Haward Corp.

Is 316 stainless steel worth the extra cost over 304?

For most applications, 304 grade has the best combination of corrosion resistance, mechanical properties, and cost. For high corrosion resistance in food, biomedical, marine, and heat exchanger applications, 316 can be worth the price difference. The resistance to solvents, chlorides, acetic acid, and especially to salt water can make 316 the preferred choice. The quality of the surface finish and the amount of cold work (most often referred to as the hardness, as in quarter-hard or half-hard) influences the corrosion resistance greatly.

Sources: Professor Roger Wright, Rensselaer Polytechnic Institute; Dr. Jack Grubb, Allegheny Ludlum; Dr. William H. Cullen, Jr., Nuclear Regulatory Commission, and Dr. Shui Lee, Central Wire Industries. Also, web sites of AK Steel, Allegheny Technologies, Carpenter Technology, Sandmeyer Steel and Haward Corporation.

What makes stainless steel stainless?

Compared to plain carbon steel, stainless steels – there are more than 300 grades — contain at least 12 percent chromium. When the chromium combines with oxygen in the atmosphere, a thin, invisible layer called the passive film forms on the surface of the steel. The protective layer is so thin – a few atoms thick — that the metallic, grayish coloration of the underlying steel is visible. If it gets scratched, the oxides quickly form again to repair the invisible layer.

Roll of 304 Stainless bound for Marlin Steel

18,000-pound roll of 304 stainless bound for Marlin Steel being sliced into sheets at Maryland Metals Processing, Baltimore

On plain carbon steel, by contrast, the layer that forms in ambient environments is a different oxide that is orange, thick, loose and porous — better known as rust. Also, stainless steel isn’t technically stainless; rather, it “stains less.” The passive film needs oxygen to repair itself, so the “self-healing” is hampered in environments of low oxygen or high salinity like seawater.

Stainless’ distinctive look is responsible for such dramatic landmarks as the Gateway Arch in St. Louis, Cloud Gate in Chicago and the Chrysler Building in New York.

Sources: Professor Roger Wright, Rensselaer Polytechnic Institute; Dr. Jack Grubb, Allegheny Ludlum; Dr. William H. Cullen, Jr., Nuclear Regulatory Commission, and Dr. Shui Lee, Central Wire Industries. Also, web sites of AK Steel, Allegheny Technologies, Carpenter Technology, Sandmeyer Steel and Haward Corporation. 




How Tim Geithner helped us add a robot and 3 employees

Dr. Marshal Greenblatt of Marlin Steel and U.S. Treasury Secretary Timothy Geithner

Dr. Marshal Greenblatt of Marlin Steel and U.S. Treasury Secretary Timothy Geithner

When we heard the news that President Obama is expected today to name his replacement for U.S. Treasury Secretary Timothy F. Geithner, we recalled the day last spring when Mr. Geithner visited our factory in Baltimore. He was pleased that we were growing in a bad economy and exporting to 36 nations in contrast to the grim picture of American manufacturing losing out to cut-rate competitors overseas. But he got particularly enthused when Dr. Marshal “Mickey” Greenblatt, a member of the board of directors at Marlin Steel, showed him the powerful sheet-metal laser cutter that Marlin had recently purchased.

“He was fairly cool and collected, but he became very animated when I described how a change in the depreciation rule allowed us to quickly invest in the new robot equipment. The change reduced the depreciation period on the purchase from five years to one so our tax bill went down. That probably enabled us to hire three workers, I told him. He jumped up on the balls of his feet very excitedly and said, ‘That was my idea. That was my idea.’”

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