MKS

it\'s a steel

by:MKS     2020-03-01
Why is stainless steel, er stainless steel?
The simple answer is that it contains at least 10.
By mass, Chrome is 5%, which is the only requirement stipulated by the UK/European stainless steel standard.
The more detailed metallurgical answer is that stainless steel is not a specific grade of steel, but a whole set of ferroalloys with one thing in common: they all contain at least 10.
Chromium accounts for 5% by quality.
It is this additional element that enhances their corrosion resistance.
Increase the chromium content to more than 10.
This resistance is increased by 5% and the most common stainless steel grades are 17 or 18%.
\"The film on stainless steel is very adhesive and inert and is self-contained
So how does the protection mechanism work?
The diameter of chromium and iron atoms that make up the alloy is very similar (about 0. 25 nanometres)
So they are easy to mix together on a regular cube grid.
In fact, this means that chromium atoms-at least one of every 10 atoms in stainless steel-are evenly dispersed throughout solid metals.
When these iron/chromium alloys are exposed to oxygen (including ambient air), the highly active chromium atoms immediately form a thin chromium-
An oxide-rich layer on a metal surface, often called a passive film.
Additional chromium atoms migrate from the body of the steel to the surface to form this oxide layer, thus forming a protective film of about 13 to 15 nanometers thick.
The passive film is very attached and inert, and most importantly, it is self-contained.
Repair in any environment containing oxygen.
British South Yorkshire Sheffield stainless steel European Standards Commission former British representative Colin Holis stumbled upon stainless steel more than 100 years ago, just before World War I
The British Army had a problem: its new explosives, the cordon, soon ran out of the barrel.
Looking for a high temperature, wear and tear
Fire-resistant steel-in Sheffield, better than hunting in the \"City of Steel\" in northern England, Harry Brisley is in charge of the Laboratory of the work selection.
He followed a promising route to turn ferroalloys with chromium.
The standard way to inspect the new alloy structure is to polish the sample and then etching the surface with acid to see the crystal structure under the microscope.
Brearley tried to etching his new alloy with nitric acid but found that his surface was still polished.
He was a little annoyed and tried another acid, but nothing better than that.
After trying several other acids, frustration turned into excitement when he realized he had found corrosion --Steel resistant.
Brearley, who was born and raised in Sheffield, knew he was the right person to take advantage of the discovery.
Tableware made in Sheffield
Silver is expensive, too soft to make sharp knives, and ordinary steel is rusted or stained.
The new steel is exactly what the machetes want.
They call it stainless steel.
Robert Senior, retired from British Steel Oakham in Latran, England. The name is a bit of a misnomer because stainless steel can be dyed.
The obvious stainless steel effect comes from the addition of chromium, the ingredients are common for most home use, but up to 26 of the ingredients are the best for the worse environment.
Other metals such as nickel can be added depending on the desired performance, which reduces the fragility at low temperatures.
Nickel also makes steel
Magnetic properties can be achieved without heat treatment.
When the chromium oxide layer formed on the surface breaks or scratches, further chromium reacts with oxygen and repairs the layer.
However, if the protective layer is destroyed by an aggressive reagent, or in a non-
Oxidation environment.
Heating also causes discoloration because it causes uneven oxidation.
Different oxide thickness in the rainbow
Like coloring, because of the interference that reflects the light-this effect can also be seen in titanium.
Joe Gassin of Stourporton-
Cévin Wooster of Worcester, England, pays £ 25 for each answer published on the New Scientist.
Answer this question or ask a New Scientist. com/lastword.
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