Weaknesses of Stainless Steel

Introduction

This report has been written to give you the reader a basic understanding of stainless steel. The report will explain how it is made, uses in industry and the strengths and weaknesses of the material.

History

Originally known as ‘rust less steel’, stainless was officially discovered between the years of 1900 and 1915. There is no exact date of creation as the discovery was the culmination of many works, the first of which is recorded in 1821. A Frenchman named Berthier found that when iron is alloyed with chromium it becomes resistant to some acids. Further developments were made in 1872, when three British scientists tried to patient their version of stainless steel which contained, 30-35% chromium and 1.5-2% tungsten, which they too declared was weather and acid resistant. Three years later in 1875 another Frenchman, Brustlien, discovered the iron used to make stainless had to have a very low carbon content, of only 0.15%, which was only discovered because ferrochrome became available.

Why this material is considered useful or important?

Stainless steel is considered to be very useful because it is ductile and malleable and produced to withstand the elements, resisting oxidation and staining.

With over 150 various different stainless steel compounds there is one to suit most applications where other metals maybe used.

Where is it found?

Stainless steel is not found, it is manufactured from various elements depending on its required use. All stainless steel begins as low carbon steel (50% or more) which is combined with 10 to 26% chromium, to create the base of all stainless steels.

which is a hard metal with a high melting point.

What are the raw materials that are used to produce this material?

The raw materials use to produce stainless steels are, a minimum of 50% low carbon steel, and at least 10% of chromium. Depending on the grade of stainless steel other elements will be added during production including nickel, nitrogen and molybdenum which will give added resistance to various forms of corrosion and can also reduce the overall weight.

What are its applications in industry?

Stainless steel is used widely across many industries such as:

Surgical tools: Forceps, needles, scissors and scalpels

Kitchen ware: Pots, pans, knives and forks

Architectural structures and panels: roofing, decorative pieces eg. Empire state building

Storage containers: For liquid chemicals to beer or milk.

Automotive parts: car exhausts, catalytic converters, trim pieces and fasteners

Marine: Handles, nuts and bolts, frames and fixtures

Even down to the most basic nuts and bolts.

The most commonly used form of stainless is 304 due to is cost, strength, versatility and finish available along with its great welding and forming characteristics. 304 is austenitic meaning it is a non metallic solid solution of iron and carbon which contains no more than 0.08% carbon, and a minimum of 8% nickel and 18% chromium

316 is the most common form of stainless steel after 304 and is often referred to as marine/ surgical grade stainless. Due to the fact that 316 is sold as a marine grade of stainless it has to resist chloride corrosion caused by salt water, so the addition of molybdenum is required. Molybdenum is a silver coloured element which has an extremely high melting point and when alloyed with steel becomes very hard and resistant to salt corrosion. This is why 316 is suitable for marine use and is also used in surgical and food and beverage applications such as milk storage tanks and piping where a sterile environment is very important. For applications where heat is an issue titanium can added to raise the melting point

321 other wise know as aircraft grade stainless has an increased resistance to temperature, withstanding 600-900°C

What are its properties; i.e., mechanical, electrical, thermal, chemical, physical, etc.

Mechanical properties of stainless steel are its ability to

What are its strengths and it limitations?

The biggest strength of stainless steel is that it has a very high resistance to oxidation. Although there are many other advantages:

Low maintenance: Rarely requires cleaning

Anti staining and wont rust: due to the chromium in stainless steel, which reacts to oxygen creating a protective surface layer over the metal, it is very hard to stain, or create rust.

High positive and negative temperatures: The ability to withstand temperature allows stainless to be used in a wide range of different environments.

Pressure: Stainless steels ability to contain high pressures make it ideal for storage containers and piping.

Malleable and ductile: Stainless is most commonly produced in coils, sheets, plates, bars and tubes of differing size.

What are the future demands and applications on this material?

Stainless steel will be use for long time to come into the future. Although there is no specific future applications that stainless will be in demand for it will be a material which will continue to be used for many years to come purely because stainless steel is 100 recyclable. Even the majority of stainless steel produced today will contain up to 60% recycled material.

Knife

http://www.valleymartialarts.com/index.php?main_page=index&cPath=3_18

Kitchen

http://www.furniturestoreblog.com/2009/01/24/the_ultimate_stainless_steel_kitchen_from_strato.html

Tubes

http://www.thomasnet.com/articles/metals-metal-products/stainless-steel-tubes

Chromium

http://en.wikipedia.org/wiki/Chromium

http://en.wikipedia.org/wiki/Molybdenum

http://www.wisegeek.com/how-is-stainless-steel-made.htm

http://www.azom.com/details.asp?ArticleID=965

http://en.wikipedia.org/wiki/SAE_steel_grades

http://en.wikipedia.org/wiki/Stainless_steel#Uses_in_sculpture.2C_building_facades_and_building_structures