Hardness of steelMohs

Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of CaC2. Its main use industrially is in the production of acetylene and calcium cyanamide.[3]

It's important to note that the Rockwell hardness scales are dimensionless numbers and are used to represent the hardness of a material based on the depth the indenter penetrates the material. The higher the Rockwell hardness number, the harder the material. Additionally, different Rockwell scales are used for different types of materials, so it's essential to specify the scale being used when reporting Rockwell hardness values.

Rockwell tends to be the most commonly used way of testing hardness, due to its speed and simplicity. It is also suitable for a wide range of materials including metals, plastics and ceramics. The Rockwell test offers several different scales (A,B,C etc.) based on different combinations of indenter types and applied loads.

Calcium carbide is used in carbide lamps. Water dripping on carbide produces acetylene gas, which burns and produces light. While these lamps gave steadier and brighter light than candles, they were dangerous in coal mines, where flammable methane gas made them a serious hazard. The presence of flammable gases in coal mines led to miner safety lamps such as the Davy lamp, in which a wire gauze reduces the risk of methane ignition. Carbide lamps were still used extensively in slate, copper, and tin mines where methane is not a serious hazard. Most miners' lamps have now been replaced by electric lamps.

This reaction was the basis of the industrial manufacture of acetylene, and is the major industrial use of calcium carbide.

In the United States, Europe, and Japan, consumption of calcium carbide is generally declining.[16] Production levels in the US during the 1990s were 236,000 tons per year.[13]

Hard anodised parts are tested for hardness using the Vickers test. On average, hard anodised aluminium 6082 can achieve values in the range of 300 to 500 HV, to put that into perspective, in its untreated state it has a hardness range of 80-95 HV. Exact hardness is entirely dependent on process parameters, such as anodising time, temperature, voltage and electrolyte composition. It’s also important to note that hardness may not be uniform across the entire material.

Precipitation hardening is also known as age hardening and is used to strengthen certain types of alloys, in particular those based on aluminium, magnesium, and some steels. The treatment itself is a three-step process, a combination of solution treatment (solutionising) and ageing.  During the first step the alloy is heated to a high temperature (also known as the solution treatment stage) it is generally heated to just below its melting point. This high heat allows metal atoms and alloying elements to dissolve into a solid solution. This treatment basically homogenises the alloy’s composition. Reducing any segregation of elements.The second step is quenching (rapidly cooling) to hold the alloy’s new microstructure.Before finally being heated at a lower temperature for a long-time (ageing). During the ageing process the alloying elements begin to separate from the solid solution. They form microscopic precipitates (particles) within the material structure. These precipitates hinder the movement of structural defects (dislocations) within the crystal lattice of the material. Consequently, impeding plastic deformation and improving strength and hardness.There are two stages within the ageing process, nucleation and growth. At the beginning, during nucleation, small clusters of precipitate atoms begin to form with the alloy’s matrix (nucleation). Nucleation sites can include crystal defects, grain boundaries, and other imperfections. During the “growth” stage and once nucleation has occurred, the precipitates grown in size and number. Then continue to hinder the movement of dislocations, effectively strengthening the material.

The Leeb hardness value is a dimensionless number, and it is usually converted to different scales to represent the hardness of the material in specific units, such as HRC (Rockwell C hardness) or HB (Brinell hardness).

Metalhardnesschart pdf

In China, acetylene derived from calcium carbide remains a raw material for the chemical industry, in particular for the production of polyvinyl chloride. Locally produced acetylene is more economical than using imported oil.[14] Production of calcium carbide in China has been increasing. In 2005 output was 8.94 million tons, with the capacity to produce 17 million tons.[15]

Nitriding – Like carburising the metal part is heated in an environment, but this time rich in not just carbon, but also nitrogen. Nitrogen atoms diffuse into the surface, forming nitrides, which increases the hardness and wear resistance. Particularly effective for use on stainless steel and other alloyed steels.

Flame Hardening – a high-temperature flame is directed onto the surface of the metal part, followed by quenching. Similar to induction hardening this method only hardens the surface layer.

Today acetylene is mainly manufactured by the partial combustion of methane or appears as a side product in the ethylene stream from cracking of hydrocarbons. Approximately 400,000 tonnes are produced this way annually (see acetylene preparation).

Hardness of steelchart

The Leeb hardness test is commonly used for on-site hardness measurements, especially in large and heavy components, where other conventional hardness tests might be impractical or not feasible. However, it's important to note that the Leeb hardness test might not be as accurate as other laboratory-based hardness tests (e.g., Brinell, Rockwell, or Vickers) and might be affected by factors such as surface roughness and material homogeneity. Calibration and standardisation are critical to obtaining reliable and accurate hardness values using the Leeb hardness test method.

Calcium carbide is produced industrially in an electric arc furnace from a mixture of lime and coke at approximately 2,200 °C (3,990 °F).[5] This is an endothermic reaction requiring 110 kilocalories (460 kJ) per mole[6] and high temperatures to drive off the carbon monoxide. This method has not changed since its invention in 1892:

The Rockwell hardness test is based on the indentation depth caused by a diamond or a ball indenter under different loads. There are two main scales used in the Rockwell test: the Rockwell HRC scale (uses a diamond cone indenter) for harder materials and the Rockwell HRB scale (uses a ball indenter) for softer materials.

Also known as surface hardening. This heat treatment is used to improve the hardness and wear resistance of the metal’s surface, whilst retaining the toughness of its inner core. This method is particularly useful for components that need to withstand abrasive wear, impact, and other forms of mechanical stress. The metal’s surface layer composition is altered through diffusion.

Calcium carbide is sold commercially as a mole repellent.[25] When it comes into contact with water, the gas produced drives moles away.[26]

Hardness of steelcalculator

The Brinell test is typically used for materials with a coarse or granular microstructure, such as cast iron, aluminium, and soft metals. It provides a reliable measurement of hardness but may not be suitable for very hard or thin materials due to the large indentation size.

The Brinell hardness test is named after its inventor, Johan August Brinell. It involves applying a constant load or force to a spherical indenter made of hardened steel or carbide onto the surface of the material being tested. The indentation diameter is then measured optically. The Brinell hardness number (BHN) is calculated as the load applied divided by the surface area of the indentation.

So now that we know about what hardness means for your part and how you can obtain hardness whilst simultaneously retaining a part’s toughness, let’s talk about testing a part’s hardness. How you test a part’s hardness and the methods that are available.

At Protolabs the majority of our datasheets include figures utilising the Brinell and Rockwell hardness tests, please see below for a selection metals we offer at Protolabs for CNC machining and their hardness values. For other materials, please check the numbers provided on our material datasheets found here. Or if unsure, please speak to one of our application engineers by phone +(0) 1952 683047 or email [email protected]

The reaction of calcium carbide with water, producing acetylene and calcium hydroxide,[5] was discovered by Friedrich Wöhler in 1862.

Calcium carbide is used to determine the moisture content of soil. When soil and calcium carbide are mixed in a closed pressure cylinder, the water content in soil reacts with calcium carbide to release acetylene whose pressure can be measured to determine the moisture content.[23][24]

The hardness of a material refers to the materials ability to resist deformation, indentation or scratches. It is a measure of the materials hardness. There are several different tests used to display the hardness of materials including, Brinell (HB), Rockwell (HRC), Vickers (HV)and Leeb.

Applications of calcium carbide include manufacture of acetylene gas, generation of acetylene in carbide lamps, manufacture of chemicals for fertilizer, and steelmaking.

Hardnessconversion calculator

For HBS a hardened steel ball was/is used to determine the value. This is used for materials with a value below 450 such as mild steel and grey cast iron, however, the HBS method isn’t really used any longer, although it is sometimes still referred to.HBW indicates a cemented carbide ball is used. This is used for materials with a value below 650. As HBW is the only method still used it is often expressed as simply HB on datasheets.

There are many methods of heat treating a part to potentially make it harder. These include quenching, precipitation hardening (ageing), case hardening and carburising, which are offered through our digital network.

Quenching is a process used to rapidly cool a heated metal or alloy to enhance its mechanical characteristics. During the process the metal or alloy is heated to a high temperature to allow for changes in its atomic structure. It is then quickly cooled down, often by immersing the part into water, oil or exposing it to cool air/steam. This “quenching” locks in the changes to the structure that occurred during the heating process. The result, parts with very high hardness. To control the resulting hardness a tempering process may be used. Tempering prolongs the service life of the part, reducing brittleness.

Carbide lamps were also used extensively as headlamps in early automobiles, motorcycles and bicycles, but have been replaced entirely by electric lamps.[18]

Hardness of steelpdf

Induction Hardening – the surface layer of the metal part is heated using high-frequency induction heating, and then the part is quenched.  The localised heating and quenching result in a hardened surface, whilst retaining core properties.

Carburising – the most common of the methods. The metal part is heated in an environment that is rich in carbon, which causes the carbon atoms to diffuse into the surface layer. The result is a surface layer high in carbon, which can be hardened through subsequent quenching (rapid cooling).

The high temperature required for this reaction is not practically achievable by traditional combustion, so the reaction is performed in an electric arc furnace with graphite electrodes. The carbide product produced generally contains around 80% calcium carbide by weight. The carbide is crushed to produce small lumps that can range from a few mm up to 50 mm. The impurities are concentrated in the finer fractions. The CaC2 content of the product is assayed by measuring the amount of acetylene produced on hydrolysis. As an example, the British and German standards for the content of the coarser fractions are 295 L/kg and 300 L/kg respectively (at 101 kPa pressure and 20 °C (68 °F) temperature). Impurities present in the carbide include calcium phosphide, which produces phosphine when hydrolysed.[7]

The Rockwell hardness test has multiple scales, each designated by a specific letter. The most common scales are Rockwell A (HRA), Rockwell B (HRB), Rockwell C (HRC), and Rockwell D (HRD). Each scale uses a different combination of the indenter and the applied load.

The pure material is colorless, while pieces of technical-grade calcium carbide are grey or brown and consist of about 80–85% of CaC2 (the rest is CaO (calcium oxide), Ca3P2 (calcium phosphide), CaS (calcium sulfide), Ca3N2 (calcium nitride), SiC (silicon carbide), C (carbon), etc.). In the presence of trace moisture, technical-grade calcium carbide emits an unpleasant odor reminiscent of garlic.[4]

Thin steel, case-hardened steel, shallow case-hardened steel, cemented carbide, other materials with relatively low hardness

Hard materials resist deformation, indentation or scratches making them harder wearing, longer lasting and often easier to clean and maintain.

This method is suitable for a wide range of materials, including metals, ceramics, and plastics. Due to its small indentation size the Vickers hardness test allows for testing on very thin materials and provides accurate results.

Hardness of steelformula

Plating, coating or surface heat treatment often aim to provide the hard and/or hard-wearing surfaces required, whilst maintaining the materials’ inherent toughness.Hard anodising is available at Protolabs, our digital network, also offer heat treatment and painting, learn more here.

Carbide lamps are still used for mining in some less wealthy countries, for example in the silver mines near Potosí, Bolivia. Carbide lamps are also still used by some cavers exploring caves and other underground areas,[17] although they are increasingly being replaced in this use by LED lights.

This reaction was an important part of the Industrial Revolution in chemistry, and was made possible in the United States as a result of massive amounts of inexpensive hydroelectric power produced at Niagara Falls before the turn of the 20th century.[8] The electric arc furnace method was discovered in 1892 by T. L. Willson, and independently in the same year by H. Moissan.[9][10][11] In Jajce, Bosnia and Herzegovina, the Austrian industrialist Josef Kranz and his "Bosnische-Elektrizitäts AG" company, whose successor later became "Elektro-Bosna", opened the largest chemical factory for the production of calcium carbide at the time in Europe in 1899. A hydroelectric power station on the Pliva river with an installed capacity of 8 MW was constructed to supply electricity for the factory, the first power station of its kind in Southeast Europe, and became operational on 24 March 1899.[12]

Calcium carbide is used in toy cannons such as the Big-Bang Cannon, as well as in bamboo cannons. In the Netherlands calcium carbide is used around new-year to shoot with milk churns.[22]

Calcium carbide is sometimes used as source of acetylene, which like ethylene gas, is a ripening agent.[19] However, this is illegal in some countries as, in the production of acetylene from calcium carbide, contamination often leads to trace production of phosphine and arsine.[20][21] These impurities can be removed by passing the acetylene gas through acidified copper sulfate solution, but, in developing countries, this precaution is often neglected.

This method is commonly used for on-site testing and is useful for large and heavy components. It is less accurate than the Brinell, Rockwell, or Vickers tests but offers the advantage of quick measurements without the need for sample preparation.

Pure calcium carbide is a colourless solid. The common crystalline form at room temperature is a distorted rock-salt structure with the C22− units lying parallel.[13] There are three different polymorphs which appear at room temperature: the tetragonal structure and two different monoclinic structures.[1]

Hardness and toughness are normally inversely proportional to each other e.g. glass is hard, but it’s low toughness makes it very fragile. Plastics are often tough, but not as resistant to surface and impact damage as metals.

What are the different types of case hardening?There are several different methods of case hardening, they include, carburising, nitriding, carbonitriding, induction hardening and flame hardening. Out digital network offers carburising.

The Vickers hardness test utilises a diamond pyramid-shaped indenter to create a small impression on the material's surface. Taking into consideration the weight of the load, the size of the indentation is measured using a microscope. The Vickers hardness number (HV) is calculated based on the indentation diagonal lengths.

HRChardnessfull form

A thin, protective coating is applied to the aluminium part, forming a protective oxide layer. This layer creates a barrier against corrosion. There is the choice of decorative anodising and hard anodising. Hard anodising is the most durable anodising finish available on machined aluminium parts.

Do you need a guide for selecting thermoplastic materials? Here you will find expert knowledge about thermoplastics and tips that will make it easier for you to choose a material for your moulded parts.

Carbonitriding – A combination of carburising and nitriding. The part is exposed to an atmosphere containing both carbon and nitrogen. This creates a surface layer rich in both carbon and nitrogen compounds.

Calcium carbide, together with calcium phosphide, is used in floating, self-igniting naval signal flares, such as those produced by the Holmes' Marine Life Protection Association.

The Leeb hardness test is a non-destructive and portable method used primarily for metals. It involves a spring-loaded end with a spherical or conical indenter. The end that makes contact with the material is released, and the rebound velocity is measured after striking the material's surface. The Leeb hardness value is then determined based on the ratio of the rebound velocity to the impact velocity.