Why does stainless steel rust easily? Why stainless steel is so hard? What is austenitic stainless steel? Martensitic stainless steel? Can Stainless steel be used in water after special treatment?
Steel is present in our daily lives, but we lack skills to understand the different material, type, manufacturing process, ect.. In order for us to have a deeper understanding of stainless steel, this article brings together technical terms and their definition. Now, you can become experts in stainless steel in 10 minutes!
Please notice that you might be interested in the other parts of the dictionary:
A guide to the language of steel: A to H (Part 1)
Active metal: Metal surface has lost its ability to resist corrosion (the passive state) under the prevailing conditions.
Alloy steel: Alloy steels have enhanced properties due to the larger proportion of elements such as manganese and silicon present in carbon steels.
Annealing: The heat treatment process by which steel products are reheated to a suitable temperature in order to remove stresses from previous processing and to soften them and/or improve their machinability and cold forming properties.
Apparent consumption: The sum of net industry shipments within a given country or region, plus its imports and minus its exports.
Austenite: The steel with the smallest building block of atomic structure of ‘face centred cubic’ (fcc) ie one atom at the eight corners of a cube and one in the centre of each of the six faces. Austenitic stainless steels are characteristically non-magnetic while this improved the weldability, formability and low temperature toughness.
Austenitising: The hardening / strengthening heat treatment of martensitic stainless steels. Normally done by the tempering treatment after cooling down.
Bar: A finished steel product, commonly in flat, square, round or hexagonal shapes, rolled from billets.
Billet: A semi-finished steel product with a square cross section up to 155mm x 155mm. This product is either rolled or continuously cast and is then transformed by rolling to obtain finished products like wire rod, merchant bars and other sections. The range of semi-finished products above 155 mm x 155 mm are called blooms.
Blank: Steel sheet of high dimensional precision, in simple or complex form, sometimes multi-thickness, constituting principally automobile body parts.
Blast furnace: A furnace used in integrated steelmaking in which coke and iron ore react together under a hot air flow to form liquid hot metal, also called pig iron.
Blast furnace (BF) Productivity: The hot metal produced (in ton), per cubic meter of blast furnace volume, per day (T/cubic met/day).
Bloom: Semi-finished product, square (can be rectangular) section of cross sectional size exceeding 5”x5” (125mm X 125mm).
Bright Annealing: An annealing process was done to prevent surface tarnish or oxidation.
Carbon steel: A type of steel that generally has only a small quantity of elements other than carbon, silicon, manganese, sulphur and phosphorus, so it has no significant alloying element.
Cathodic protection: It is one of the methods to increase the metal surface’s corrosion resistance ability.
Chlorides (halides): It formed from chlorine (fluorine, bromine, iodine) atoms. This can be the reason why localised attack mechanisms such as crevice, pitting and stress corrosion cracking occurred.
Coal: The primary fuel used by integrated iron and steel producers.
Coated steels: Steel is coated by a heat process, or through electrolysis, with a layer to protect the metal base against corrosion. The most commonly used coating material is zinc which can be applied either using the heat process (hot-dip galvanising) or using electrolysis (electro-galvanising). An organic coating (paint, plastic) can also be deposited on the zinc layer.
Coil: A finished steel product such as sheet or strip which has been wound or coiled after rolling.
Coke: A form of carbonised coal burned in blast furnaces to reduce iron ore pellets or other iron-bearing materials iron.
Coke ovens: Ovens where coke is produced. Coal is usually dropped into the ovens through openings in the roof, and heated by gas burning in flues in the walls within the coke oven battery. After heating for about 18 hours, the end doors are removed and a ram pushes the coke into a quenching car for cooling before delivery to the blast furnace.
Coke Rate: Represented in kg, of BF Coke consumed per tonne of Hot Metal produced in the blast furnace (Kg/THM).
Coking Coal : Coking coals need to get through the process, Carbonisation. The coke that produced is in a strong and porous mass.
Metallurgical Coke: Only good quality coke made from specific blend of coking coal can be used in metallurgical operations. (Called met coke)
Blast Furnace (BF) Coke: Met Coke that are used for iron making in BF.
Non-coking coal (NCC): NCC is with poor coking properties. For example, NCC does not soften and form cake like coking coal during carbonization in the coke oven.
Coking time : Time required for conversion of coal to coke in the coke oven. The coking time is from 15-20 hours. which varies in the range of 15- 20 hrs.
Cold rolling: Passing a sheet or strip that has previously been hot rolled and picked through cold rolls (below the softening temperature of the metal). Cold rolling makes a product that is thinner, smoother and stronger than can be made by hot rolling alone.
Continuous casting: A process for solidifying steel in the form of a continuous strand rather than individual ingots. Molten steel is poured into open-bottomed, water-cooled moulds. As the molten steel passes through the mould, the outer shell solidifies.
Colour coated products: Steel products coated with PVC/ plastics or any other organic material.
Corrosion: An electrochemical process in which metal atoms are removed from the surface of the metal.
CRC: Cold rolled coil (see cold rolling)
Crude steel: Steel in the first solid state after melting, suitable for further processing or for sale. Synonymous with raw steel.
Direct reduction: A group of processes for making iron from ore without exceeding the melting temperature. No blast furnace is needed.
Duplex: Steel that mix with austenite and ferrite. It has higher mechanical strength and stress corrosion cracking resistance.
Electric arc furnace: A furnace for scrap-based steelmaking. Once the furnace is charged and covered, graphite electrodes are lowered through holes in the roof. The electric arc travelling between the electrodes and the metallic charge creates intense heat which melts the scrap. Alloying elements can be added during the process.
Electrical steels: Specially manufactured cold rolled sheet and strip containing silicon, processed to develop definite magnetic characteristics for use by the electrical industry.
Fatigue (endurance): A gradual mechanical failure mechanism caused by oscillating (cyclic) stresses, like vibration over continuous stress reversals.
Ferrite: Steel with the smallest building block of atomic structure of ‘body centred cubic’ (bcc) ie one atom at the eight corners of a cube and one in the centre of the cube. Ferritic stainless steel is magnetic.
Ferro Alloys: Master alloys used for de-gassing/ de-oxidising or alloying in steel making. They are usually ferro silicon, ferro manganese, silico manganese, ferro chrome, ferro nickel etc.
Flat products: A type that is produced by rolls with smooth surfaces and ranges of dimension, varying in thickness. The two major flat steel product categories are thin, flat products (between 1mm and 10mm in thickness) and plates (between 10mm and 200mm thick and used for large welded pipes, ship building, construction, major works and boilers).
Fluxes: Usually used in Iron/ Steel making, such as limestone, dolomite. To removed ash slag and impurities.
Galfan alloy coated sheets: Cold rolled sheet/strips coated with Zinc-Aluminium alloy. It consists of 95% zinc and 5% aluminium. It has better corrosion properties.
Galvalume alloy coated sheets: Cold rolled sheet/strips coated with alloy (55% aluminium and 45% zinc with nominal amount of silicon.) It has better high temperature performance.
Galvanised steel: Produced when hot or cold rolled sheet or strip is coated with zinc, either by the hot-dipping or electrolytic deposition processes. Zinc coating applied by the hot dip method is normally heavy enough to resist corrosion without additional protective coating. Materials electronically galvanised are not used for corrosion-resistant applications without subsequent chemical treatment and painting, except in mild corrosive conditions, due to the thin coating of zinc. Galvanise is a pure zinc coating. A special heat-treating process converts the pure zinc coating to a zinc/iron alloy coating, and the product is known as Galvanneal.
Hardening: Accompanied with the heat treatment processes (austenitising and tempering). Cold work can increase the hardness of austenitic stainless steel as well.
High Speed Steel (HSS): Alloy steel which consist of tungsten, vanadium, chromium, cobalt and other metals.HSS commonly used for manufacture of cutting tools.
HDG: Hot dip galvanised (see galvanised steel)
Hot Working: Forging done above the recrystallisation temperature of the steel. Do not need to do annealing after hot working.
Hot-rolling mill: Equipment on which solidified steel preheated to a high temperature is continuously rolled between two rotating cylinders.
Cold rolling mill: Equipment that reduces the thickness of flat steel products by rolling the metal between alloy steel cylinders at room temperature.
Hot metal/Liquid Iron: Molten iron produced in the blast furnace.
HRC: Hot rolled coil
List of References:
Credit to British Stainless Steel Association
American Iron and Steel Institute
Callister, W., Fundamentals of Materials Science and Engineering, 2nd ed. (New York: Wiley & Sons, 2004), pp. 252.
Carter, C. and Norton, M., Ceramic Materials: Science and Engineering (Berlin: Springer, 2007)
Shettleworth, S., Cognition, Evolution and Behavior, 2nd. (Oxford: Oxford University Press, 2010)
Eagleson, M., Concise Encyclopedia Chemistry Revised (Berlin: Walter de Gruyter, 1994), p. 834.
Ferdinand, B. and Johnston, R., Mechanics of Materials, 2nd. (New York: McGraw-Hill, Inc.: 1992), p. 51.
Reed-Hill, R. and Abbaschian, R., Physical Metallurgy Principles, 3rd (Boston: PWS-Kent Publishing: 1991)
Rodney, P., Scientific American Inventions and Discoveries (New York: Wiley & Sons, 2004), p. 380.
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