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How Stainless Steel is Made

What we call stainless steel is actually a blanket term for a family of metals selected for engineering because of their resistance to heat and corrosion. Stainless steels are all iron-based alloys, or mixtures of iron and other metals, made up of at least 10.5% chromium. This chromium content reacts with oxygen and moisture in the air to form a very thin, yet very effective protective film that adheres to the surface of the metal. Though this boundary layer is only 2-3 nanometres thick, it covers the entire surface of the material. When scratched or abraded in any way, it self repairs as the chromium reacts with oxygen and moisture to reform the oxide layer. Increasing the chromium content beyond this 10.5% minimum gives the material even greater corrosion resistance properties.

Different kinds of steel piping

Other metals can be added to the alloy as well, each changing the properties of the resulting stainless steel composition in particular ways. Nickel is a common stainless steel alloy, and the addition of 8% or more can improve corrosion resistance as well as provide a range of other properties. Molybdenum provides further corrosion resistance as well, and nitrogen increases strength and resistance. The addition of other elements in different ratios can add or subtract from corrosion resistance, hardness, strength, or toughness.

Different Kinds of Steel

The different kinds of stainless steels can be classified based on the other metals they are alloyed with. The four basic stainless steel families are ferritic, martensitic, austenitic, and duplex. Within these family groups, there is a range of grades based on the range of their composition and defined by standards that vary by country.

Ferritic Steels

Ferritic SteelFerritic steels, for example, have a body-centered-cubic structure, like iron at room temperature, and are mainly alloyed with chromium. Not only is ferritic steel not hardenable by heat treatment, there is also a very low carbon content, together resulting in steel with limited strength. This strength limitation renders it a poor weld steel when welded in thick sections compared to other stainless families. It is also unacceptable for sub-zero temperatures, as it becomes brittle. Despite its comparatively low strength, ferritic steel’s ferromagnetic properties make it useful for other applications. It also has superior corrosion resisance to martensitic stainless steels.

Martensitic Steels

Martensitic steels have a body-centered tetragonal lattice similar to ferritic steels, and their principal alloyed element is also chromium, at a similar rate. Unlike ferritic steels, martensitic stainless steels contain carbon, and can therefore be hardened and strengthened with heat treatment. Increasing the content of carbon in martensitic steels increases its resistance to scratching but decreases its toughness, or ability to absorb impact energy. With added nitrogen and nickel, and lowered carbon, martensitic steels have improved toughness, weldability, and corrosion resistance.


Austenitic Stainless Steels


Austenitic Stainless SteelAustenitic stainless steels are perhaps the most common kind of steel, as they are even more corrosion-resistant than ferritic and martensitic stainless steels. Austenitic stainless steel, like ferritic and martensitic steels, consists of chromium and iron, as well as nickel, and sometimes other alloying elemnets like molybdenum. Surgical steel, for example, or “SAE 304 stainless steel,” is the most familiar of this family, containing 18–20% chromium and 8–10% nickel. Austenitic grade stainless steels have superior corrosion resistance to both ferric and martensitic stainless steels. They do not exhibit a yield point, are extremely formable, and tough in extemely cold temperatures. They do not conduct heat well, and are nonmagnetic.

Duplex Stainless Steels

Duplex stainless steels are alloys of chromium, nickel, molybdenum, copper, and iron. Their microstructure consists of austenite and ferrite, matching the corrosion resistance of austenitic steels with the strength of ferritic steels. It is possible to weld duplex steels, but a balance of austenite and ferrite must be maintained, and forming duplex steels is possible but requires greater force than for austenitic stainless steels.

How Is it Made?

Melting

To make stainless steels, the raw materials must be melted together in extremely intense heat in an electric furnace, usually for 8 to 12 hours. After the materials are melted, the molten steel is cast into various forms, depending on what the steel will ultimately be used for. These forms might be rectangular-shaped “blooms”, small round or square “billets”, slabs, rods, or tube rounds.

Melting Steels

Casting and Forming

Once the steel is melted and cast, it must be formed into its final shape. In order to do so, it goes through a process called being “hot rolled,” or heated again and rolled through huge rollers. If the molten steel has been cast into blooms or into billets, it will then be formed into 0.5 inch steel wire, or 0.25 inch (.63 cm) steel bar, available in a variety of shapes like rounds, squares, octagons, or hexagons. 3 Slabs of molten steel will be formed into plate, strip and sheet steel, all of which are classified by size. Plate steel is .47cm thick, and over 25cm wide. Strip is less than .47 cm thick, and less than 61cm wide. Sheet is less than .47cm thick, and more than 61cm wide.

Annealing

AnnealingOnce the stainless steel has been formed into its final shape, it usually must be annealed. Annealing steel involves heating it and subsequently cooling it, which relieves internal stresses and softens the steel. It is possible to age harden, or heat treat, steel in order to give it greater strength, but this can be quite difficult to do, as any small changes can dramatically affect the properties of the finished product. Lower temperatures can cause higher strength and lower fracture toughness (i.e. cause the steel to be more brittle than ductile), and higher temperatures do the opposite, causing the steel to be tougher but of lower strength (i.e. more ductile than brittle).

Heat Treating

The steel can be heated at any rate to reach the temperature required to age harden it, which is 900 to 1000 degrees Fahrenheit or 482 to 537 degrees Celsius,3 but the cooling rate must be carefully controlled. If the steel is rapidly cooled by quenching it in cold water immediately, the toughness can increase without losing strength. One example of this quenching process involves dipping the hot steel in a near-freezing ice-water bath for at least two hours. Different types of steels need to be treated in different ways. Austenitic steels need to be heated to a temperature greater than 1900 degrees Farenheit, and then quenched in water for thick sections or in air for thin sections. The steel has to be cooled relatively quickly to keep it clean.

Heat Treating SteelAnnealing, or the heat treatment, can cause a precipitate known as scale to build up on the steel. This scale can be removed in several ways, most commonly with a method known as pickling: a nitric-hydrofluoric acid bath. Another method of descaling is known as electrocleaning, which involves the application of an electric current to the surface of the steel using a cathode and phosphoric acid.3 Either of these methods can remove the scale from the steel. Descaling and annealing can be introduced to the steel at different stages in the process, depending on the type of steel being created. Sheet and strip steel, for example, are annealed and descaled immediately after they are hot rolled. They are then cold rolled, or passed through rolls at a much lower temperature to reduce thickness, before being annealed and descaled again. Bar and wire forms have to go through extra steps known as forging and extruding.

Cutting

After the steel is melted, cast, formed, heat treated, annealed, and then pickled or electrocleaned, it must be cut into its desired shape and size. It can be cut mechanically, using guillotine knives for straight shearing or circular knives for circle shearing. Nibbling involves cuting a series of overlapping holes, and blanking involves metal punches and dies to punch the shape out by shearing it.4 Stainless steel can also be flame cut, involving an oxygen, propane, and iron powder flame, or cut using the plasma jet cutting method, where an ionized gas column melts and cuts the metal.

Different Surface FinishesSurface Finishing

The final step in the manufacturing of stainless steel is the surface finish, which is necessary to give stainless steel the smooth, reflective surface that it is associated with. Surface finishing also provides further corrosion resistance, and makes the stainless steel easier to clean. Different finishes are applied based on the intended application of the stainless steel. Dull finishes are produced by the hot rolling, annealing, and descaling process. A bright, reflective finish can be produced using cold rolling and annealing, or by grinding or buffing using abrasives. To achieve a mirror finish, the steel must be polished with extremely fine abrasives using grinding wheels or an abrasive belt, and then buffed extensively with cloth wheels and cutting compounds made of very fine abrasive particles.

The Many Uses of Stainless

There is an extremely wide variety of applications for every variety and grade of stainless steel that is manufactured. We use stainless steel in the restaurant and hospitality industry, in the chemical industry, in the hospital and health care industries, and in manufacturing. The great number of uses that stainless steel has will only continue to expand, as its corrosion resistance remains important and new mechanical characteristics are recognized.

Kitchenware and Cutlery

Kitchenware made in stainlessStainless steels are perhaps best known for their use in kitchenware and cutlery. Fine cutlery like knives use grade 410 and 420, or martensitic steel, which can be hardened and tempered to take and hold a sharp blade. This grade of steel is magnetic, which allows for the use of magnetic knife racks that are seen in some kitchens. Cutlery like forks and spoons are typically grade 304 stainless steel, which is a basic austenitic steel alloy of 18% chromium and 8% nickel. The 18/8 steel can tarnish, but it is ductile and resistant to corrosion, rusting and oxidizing acids. Type 304 stainless steel is perhaps the most common stainless steel and has uses in nearly every industry.

Type 304 is used extensively, along with type 316, in the food production and service industries. Stainless steel delivers no taste to food, making it of great use in kitchens everywhere. And though its anti-corrosive properties are useful, the popularity of stainless steel in the food industry is rather because stainless steel—especially type 316—is so quickly and efficiently cleaned. Type 316 is designed to hold up under tough anti-bacterial treatments.5 The medical industry uses stainless steel for similar reasons, employing stainless steel as standard for many kinds of hospital equipments because it is so easy to clean.

Industrial Uses

Stainless Steel Industrial TanksStainless steel is used extensively in pipes, tanks, pumps, and valves in the chemical, processing, and oil and gas industries because of its non reactivity. One of the first uses for type 304 stainless steel was in the storage of dilute nitric acid, because even in thinner sections it did not corrode.5 Since then, different grades and types of stainless steel have been developed to be resistant to corrosion at very hot and very cold temperatures, making stainless steel an important metal for desalination and sewage plants as well as offshore oil rigs, harbor supports, and ship propellers.

The power generation industry has great use for stainless steel and other corrosion resistant alloys. Nickel alloys are particularly useful in the power industry for its high temperature strength and resistance to oxidation by fossil fuels. Even the nuclear power industry uses stainless steel extensively. Low-cobalt stainless steel is especially useful here.

Engineering and Automotive Industry

Stainless steel is used increasingly in building and construction as well as plumbing, as it is low-maintenance to upkeep and difficult to vandalize. And because it will not rust, even expensive stainless steel reinforcing bar can be used with concrete, and costs less over a life cycle because it does not have to be replaced or repaired.5 Stainless steel is used in the automotive industry for similar reasons, for exhaust systems and catalytic converters mostly, but also for general structure.

Stainless steel is an incredible material whose uses we continue to uncover. As we grow more concerned with the environment, and as our manufacturing industries expand, our uses for stainless steel continue to grow. Our ability to manufacture steel with properties that match the need lends itself to every industry, and our uses for stainless steel will likely only grow as we discover more of its properties.

Sources

1. http://www.bssa.org.uk/topics.php?article=20

2. http://www.worldstainless.org/Files/issf/non-image-files/PDF/TheStainlessSteelFamily.pdf

3. http://www.madehow.com/Volume-1/Stainless-Steel.html

4. https://sciencestruck.com/process-to-make-stainless-steel

5. http://www.stainless-steel-world.net/basicfacts/overview-of-typical-applications-for-stainless-
steels.html

6. https://www.assda.asn.au/

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The Advantages of Stainless Steel Fabrication

In the recent years, there has been an increased use of stainless steel metal in home décor. The shiny properties of the metal make a great choice for the interior decorations. Apart from that, stainless steel is gaining a lot of popularity in plumbing works. 

Why Use Stainless Steel Fabrication for Plumbing

Why should you choose stainless steel for your plumbing work? Here are the key advantages of stainless steel fabrication in plumbing:

Long-Term Value

Urinal Cistern Sparge AdaptorThis is one of the key benefits you will enjoy by using stainless steel for your plumbing work. It is not affected by rust and corrosion. That’s what gives it an extended lifespan compared to most of the metals used in plumbing.  If you have it in your bathroom, garage or car wash drains, you will have it for years without thinking of a replacement. It does not require frequent maintenance, and thus it’s an investment that will give great value for money.

Fire and Heat Resistant

This is a great property that adds serious value to your plumbing system. If the house accidentally catches fire, the stainless steel will never get affected. With the heat resistant properties, it makes the metal a great choice for a system supplied by the hot water system. It’s the perfect material for boilers, hot water tanks, feedwater heater, and valves among many other plumbing features. These properties are among the top reasons why kitchen taps and stainless steel sinks are increasingly becoming popular in the modern homes.  They can withstand heat from hot water for a long time and still remain as good as new.

Corrosion resistant

Most of the plumbing problems such as clogging are as a result of corrosion of the piping system. Once the piping system starts corroding, foreign object, debris, and grease start to build-up over the time to the point of causing serious clogs. With stainless steel, it’s not affected by corrosions, and thus the piping system will always remain smooth to allow for easy passage of the sewer. Stainless steel it’s not affected by acids, and that’s why grated and linear drains are highly recommended for garages and car wash due to the acidic nature of these places.

100 Percent Recyclable

The best thing stainless steel is that it doesn’t go to waste. It can be used again. Over 50% of this metal comes from previously melted stainless steel products, and thus you can resell your old pieces. On the other hand, it’s environmentally friendly since it does not require a lot of mining to meet the demand. So, if you invest in this system, you can rest assured that you can resell the pieces as scrap metal at the end.

Aesthetics and value

Stainless steel features look great for aesthetic purposes. Whether you are using it for sinks, decorating stairs, kitchen taps or appliances, it will make your place look great. In fact, if you have done your plumbing and décor with stainless steel, it will significantly increase the price in the case of resale.

The stainless look has become so popular in recent years that people are now using it to showcase more than just their plumbing and kitchens. You may or may not know but stainless steel fabrication is important for a large number of other industries too. Examples of industries that rely heavily on stainless products are construction, automotive, medical, energy and food and catering.

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Privacy Policy

The privacy of your personal information is afforded the highest level of importance by 3monkeez Pty Ltd. We are bound by the Privacy Act 1988 (Cth) regarding the manner in which we handle your personal information and how we respond to your requests to access and correct it. This document sets out our information handling procedures and the rights and obligations that both you and we have in relation to your personal information.

How we collect your information

We primarily collect information about you through correspondence we engage in with you, for example, through application forms, telephone conversations and emails. We also collect information from sources that are publicly available such as websites, journals and phone books. Sometimes, we collect information about our customers from our sales agents and distributors who have direct contact with you on our behalf. We do not make use of cookies on our website to collect personal information about visitors to the site.

Kinds of information that we hold about you

We only hold information about you if it is relevant to providing the services and products that we provide. Such information generally includes your name, contact details, type of business, payment details, account number, records of correspondence and billing statements. If you are one of our suppliers, we may collect other information about you that we feel is necessary, such as the nature of the products or services that you supply, quotes that you provide and your direct credit details,. If you are a non-profit organisation that we have agreed to assist, we may collect information about how you make use of the products or services that we provide to you.

How we hold your information

Depending on the circumstances, we may hold your information in either hardcopy or electronic form, or both. Our client database is held in electronic format.

How we use your information

We use your personal information:

  • to provide you with our products and services;
  • to administer our customer relationship with you;
  • for internal purposes such as procedural assessments, risk management, product and service reviews, staff training, accounting and billing; and
  • To identify, and inform you of products and services that may be of interest to you.

If you are one of our suppliers, we may use your information to facilitate our business relationship with you, for example, to assess goods or services that you supply or to review a commercial proposal that you have put to us.

How we disclose your information

Generally, we will only disclose your personal information for a purpose that is related to the product or service that we are providing to you. This may include disclosures to organisations that provide us with professional advice, such as solicitors, accountants and business advisors, and to contractors to whom we out-source certain functions, such as mailing houses, electronic network administrators and debt collection agencies. However, where possible, we take contractual measures, and in all other circumstances, take all reasonable measures, with our contractors to ensure that they comply with the privacy standards set out in the Privacy Act 1988 (Cth). If the information we are disclosing is of a highly sensitive nature, we require our contractors to complete their work in-house and do not permit them to disclose information to sub-contractors. We may also disclose information where it is expressly permitted under the Privacy Act 1988 (Cth), for example, where it is with your consent or where we are legally required to do so, such as under a court order or taxation laws.

How we secure your information

We hold all hardcopy and electronic records of personal information in a secure manner to ensure that they are protected from unauthorised access, modification or disclosure. Our staff follow strict information handling procedures and we only permit those staff whose tasks require use of your information to access it. We delete your personal information once it is no longer needed or required to be kept by law by shredding hardcopy records and deleting electronic records.

Your right to lodge a complaint

If you are not satisfied with how we have handled your personal information, you are entitled to lodge a complaint with the Federal Privacy Commissioner. Information regarding how to lodge a complaint is available from the Commissioner’s website at www.privacy.gov.au or by ringing the Commissioner’s information line on 1300 363 9921300 363 992. However, before investigating a complaint, the Commissioner is legally required to be satisfied that you have first expressed your concern to us to afford us an opportunity to resolve the complaint directly, unless it is inappropriate for you to do so. You may lodge a complaint with our CEO either by mail at 3monkeez Pty Ltd Unit 6/24 Wellington St, Riverstone, NSW, 2765 by telephone on (02) 9627 6111(02) 9627 6111 or by email to andrew@3monkeez.com.au .We will inform you of who will handle your complaint and you may contact our CEO to enquire about its stage of progress at any time. We will go to great lengths to ensure that your complaint is resolved to your satisfaction.

Your right of access

You may request access to your personal information at any time by sending a written request to our CEO by mail at Unit 6/24 Wellington St, Riverstone, NSW, 2765 by facsimile on (02) 9627 3111, or by email to andrew@3monkeez.com.au  In your request, please state how you would like to obtain access. For example, you may like to inspect our records at our premises or you may prefer to be sent a photocopy or an electronic version of your information. You do not need to provide a reason for your request. Once our CEO has verified your identity, your request will be forwarded to our accounts manager who will arrange for access to be provided to you in an appropriate manner within 14 days. We may charge a small fee for providing access if it requires a significant amount of time to locate your information or to collate or present it in an appropriate form. If your account is held in conjunction with another individual, we will provide each person named on the account with access to information held about each account holder. Our CEO will follow up your request to ensure that the level of access with which you have been provided is to your satisfaction.

In rare circumstances, and only where it is permitted under the Privacy Act 1988 (Cth), we may not be able to provide you with access to your information; for example, where it will have an unreasonable impact upon the privacy of others, where it relates to legal proceedings between us through which the information would not otherwise be available, where it would be prejudicial to negotiations we are holding with you, where we are required by law to withhold the information or where it would reveal information relating to our commercially sensitive decision making processes. If we are unable to provide you with access, we will state why this is so and consider whether the use of an intermediary would be appropriate to provide you with an explanation of your personal information.

You may correct your information

If your personal information is out-of-date or incorrect, you may inform us of this and we will correct it for you. In the unlikely event that we disagree about the accuracy of the information and are unable to change it, you may provide us with a statement indicating that you dispute its accuracy and we will associate the statement with your information in such a manner that it will be brought to the attention of each person who uses the information.

Promotional information

We would like to send you promotional information about goods and services that we believe may be of interest to you, however, we understand that you may not wish to receive such material. If so, please inform our Sales Manager of this in writing by mail at Unit 6/24 Wellington St, Riverstone, NSW, 2765, by facsimile on (02) 9627 3111 or by email to admin@3monkeez.com.au and we’ll ensure that your name is removed from our mailing list.

Transfer of your information overseas

We will only transfer your personal information overseas if the transfer is to you, or to one of your authorised representatives, or it is with your express consent. We will not send your information outside of Australia in any other circumstances.

We may need to change our privacy policy from time to time

Due to changing business circumstances; we may need to change our privacy policy from time to time. If we do, we will endeavour to ensure that you’re overall level of privacy protection is not diminished and will publish the changes on our website. Any actions that we have take before the change will continue to be regulated by the privacy policy that existed before the changes were made.

Further information

We are happy to provide you with further information regarding your privacy. If you have any queries or requests in this respect, please contact our CEO either by mail at Unit 6/24 Wellington St, Riverstone, NSW, 2765, by telephone on (02) 9627 6111(02) 9627 6111, by facsimile on (02) 9627 3111 or by email to andrew@3monkeez.com.au.

Links

Our website may contain links to other websites and those third party websites may collect personal information about you. We are not responsible for the privacy practices of other businesses or the content of the web sites that are linked to our web site. 3monkeez Pty Ltd advises users to be aware when they leave the site that they should read the privacy statement of each and every web site that collects personally identifiable information.