Search Results - Tempering
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Tempering is a heat treatment technique for metals, alloys and glass. In steels, tempering is done to "toughen" the metal by transforming brittle martensite into bainite or a combination of ferrite and cementite. Precipitation hardening alloys, like many grades of aluminum and superalloys, are tempered to precipitate intermetallic particles which strengthen the metal. Tempering is accomplished by a controlled reheating of the work piece to a temperature below its lower critical temperature. The brittle martensite becomes strong and ductile after it is tempered. Carbon atoms were trapped in the austenite when it was rapidly cooled, typically by oil or water quenching, forming the martensite. The martensite becomes strong after being tempered because when reheated, the microstructure can rearrange and the carbon atoms can diffuse out of the distorted BCT structure. After the carbon diffuses, the result is nearly pure ferrite. In metallurgy, there is always a tradeoff between strength and ductility. This delicate balance highlights many of the subtleties inherent to the tempering process. Precise control of time and temperature during the tempering process are critical to achieve a metal with well balanced mechanical properties. Typically steel is heat treated in a multi-step process. First it is heated to create a solid solution of iron and carbon in a process called austenizing. Austenizing is followed by quenching to produce a martensitic microstructure. The steel is then tempered by heating between the ranges of 150°C-260°C (300°F-500°F) and 370°C-650°C (700°F-1200°F). Tempering in the range of 260°C-370°C (500°F-700°F) is sometimes avoided to reduce temper brittling. The steel is held at that temperature until the carbon trapped in the martensite diffuses to produce a chemical composition with the potential to create either bainite or pearlite (a crystal structure formed from a mixture of ferrite and cementite). It should be noted that when producing a truly bainitic or pearlitic steel the steel must be once again taken up to the austenite region (austenizing) and cooled slowly to a controlled temperature before being fully quenched to a low temperature. In bainitic steels, upper bainite or lower bainite may form depending on the length and temperature of the tempering process. It is thermodynamically impossible that the martensite will be totally converted during tempering, so a mixture of martensite, bainite, ferrite and cementite is often formed.
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Showing 1 to 16 of 16 Articles matching 'Tempering' in related articles. |
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1. Weak US Housing Numbers Reported
October 20, 2009
Weak U.S. housing data is tempering enthusiasm stoked by upbeat
earnings reports from some of America's best-known corporations. From technology giant
Apple to construction-equipment maker Caterpillar, a flurry of
corporate heavyweights have topped earnings and profit expectations for
the third quarter of the year, turning in strong performances in one of
the toughest global economic climates in decades.The earnings
reports would seem to validate an upward march by stock markets in the
United States, where the Dow Jones Industrial Average recently topped
10,000 for the first time in a year.U.... (read more)
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2. Are you familiar with Chocolates
October 01, 2009
We all love eating chocolates. But we don’t know the basics of chocolates such as where it comes from, how they manufacture it, the types of chocolates etc
basically the ingredients of chocolates are same cocoa butter, cocoa, sugar and milk. Hot chocolates are fine powder that could be used as beverage next to milk and sugar. Preparation of chocolates may be by two processes there are handmade chocolates and factory manufactured chocolates.
Chocolate Manufacturing process: there are about two forms of process in which the bitter cocoa solids are treated and in the other process the ... (read more)
Author: Sukirti Gupta
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3. Use of glass for home improvement and safety
August 26, 2009
Toughened glass is the right choice if you are looking for strong and heat resistant glass. Annealed glass is made to undergo thermal tempering to produce toughened glass. This process involves heating annealed glass to high temperatures and then cooling it rapidly. Toughened glass is susceptible to scratches. This problem is countered by providing a coating over the surface of the toughened glass. This type of glass is known as laminated glass. HW Glass manufactures two variations of toughened glass - heat strengthened glass that provides strength and durability and fully tempered glass that ... (read more)
Author: Paul Johnson
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4. Using Chocolate Molds to Mold Chocolate
May 12, 2009
Using chocolate molds to mold chocolate is a very simple process and can be a lot of fun too! Chocolate molds are available in a variety of shapes and themes and can be found at your local craft store or at various on-line stores. You will also need to use chocolate melting wafers such as Merckens chocolate wafers, which are very easy to use and do not require the tempering that real chocolate does. We will cover chocolate tempering in another article. For now, let's start with the basics.
Select your desired chocolate molds and make sure they are clean and dry. Dig out your ba... (read more)
Author: Thomas Newkirk
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5. Melting Chocolate From Craft Stores
April 24, 2009
When you buy chocolate from the craft store, these are usually sold in blocks which is ready to be transformed into different shapes. To make that happen, you have to melt it.
Melting is not the same thing as tempering so never confuse the two. However, melting is part of the tempering process which can be done using a microwave or a hot water bath.
The nice thing about using a microwave to melt chocolate is that you get the results you want fast with little or no effort at all and mess. Naturally, before you put the chocolate in the microwave, you should put this in a microwave sa... (read more)
Author: Julie Spear
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6. Power Tube Type PT Make-Up Air System
April 24, 2009
Canada Blower is a developer of various types of air moving systems. It developed a PT Power Tube Make-Up Air System - one of the most economical options for larger industrial plants ventilation air make up systems.
PT Air Make-Up fan system is a new ventilation concept. It utilizes some aerodynamic principles for supplying, tempering and distributing make-up air in a building in cold weather. It offers more efficiency, economy and comfort than most conventional make-up air units.
When exhaust fans are used to provide ventilation, both for industrial and process exhaust and personne... (read more)
Author: Susan Terlitski
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7. Pros and cons of toughened glass
April 10, 2009
If you are looking for strong and heat-resistant glass, toughened glass is the right one. While manufacturing toughened glass, its inner layer undergoes a greater contraction. This adds to the strength of the glass. Toughened glass is prepared from annealed glass through the process of thermal tempering. Annealed glass is heated up to 720 °C and then cooled rapidly to manufacture toughened glass. Surface of toughened glass is less hard compared to the annealed glass. It makes the glass scratch susceptible. However, to counter this problem glass manufactures are now manufacturing laminated glas... (read more)
Author: Paul Johnson
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8. Ventilation by Power Tube Make-Up Air System
January 09, 2009
NISCO Fan Co. distributes all kinds of industrial air moving equipment. It developed a PT Power Tube Make-Up Air System - one of the most economical options for larger industrial plants ventilation air make up systems.
PT Power Tube Air Make-Up fan system is a new ventilation concept. It utilizes some aerodynamic principles for supplying, tempering and distributing make-up air in a building in cold weather. It offers more efficiency, economy and comfort than most conventional make-up air units.
When exhaust fans are used to provide ventilation, both for industrial and process exhaus... (read more)
Author: Oleg Tchechel
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9. New Power Tube Make-Up Air System
December 22, 2008
Industrial Pressure Blower Co. designs different kinds of industrial and commercial air moving equipment. It developed a PT Power Tube Make-Up Air System - one of the most economical options for larger industrial plants ventilation air make up systems.
PT Air Make-Up fan system is a new ventilation concept. It utilizes some aerodynamic principles for supplying, tempering and distributing make-up air in a building in cold weather. It offers more efficiency, economy and comfort than most conventional make-up air units.
When exhaust fans are used to provide ventilation, both for indust... (read more)
Author: Susan Terlitski
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10. Make-Up Air System - Power Tube Fan
November 07, 2008
Tenderall Fan Co. has developed a PT Power Tube Make-Up Air System - one of the most economical options for larger industrial plants ventilation air make up systems.
PT Air Make-Up fan system is a new ventilation concept. It utilizes some aerodynamic principles for supplying, tempering and distributing make-up air in a building in cold weather. It offers more efficiency, economy and comfort than most conventional make-up air units.
When exhaust fans are used to provide ventilation, both for industrial and process exhaust and personnel comfort, a negative air pressure is created withi... (read more)
Author: Oleg Chetchel
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11. European painting - an outdated concept
July 31, 2008
Europe has always been known for its cultural diversity, for being an entity forged by history and geography into a multiethnic and disparate whole, displaying a characteristic plural identity against a common backdrop. Hence, the vast diversity that the European continent has brought to the art of pictorial expression has been remarkable throughout the ages. The multiplicity in unity was the natural outcome of the relative isolation of the different parts and the tempering characteristic of having the same basic conditioning. However, modern times tend rightly to use the term 'European' so... (read more)
Author: Michael de Bruges
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12. Power Tube Make-Up Air System
July 10, 2008
Canada Blower is an engineering company for air moving equipment. It developed a PT Power Tube Make-Up Air System - one of the most economical options for larger industrial plants ventilation air make up systems.
PT Air Make-Up fan system is a new ventilation concept. It utilizes some aerodynamic principles for supplying, tempering and distributing make-up air in a building in cold weather. It offers more efficiency, economy and comfort than most conventional make-up air units.
When exhaust fans are used to provide ventilation, both for industrial and process exhaust and personnel c... (read more)
Author: Oleg Tchetchel
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13. Being a Wise Patriot
May 20, 2008
Abstract: China had long been a miserable country before liberation, tempering the strong sense of national unity as well as persistent spirit of China. Hence, whenever China was confronted with predicaments in the following peaceful era, her people would stand up and backup her selflessly. This strong sense of patriotism has been cherished and praised as the nation’s spirit wealth. However, people sometimes become so hotheaded and impulsive that the harmless resistance or rebellion will finally escalate in intensity. The recent Tibet and Olympic issues are such examples, in which Chinese trad... (read more)
Author: lzqly lylzq
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14. Ice Sculptures
November 11, 2007
When it comes to breathtaking scenery there is very little that can compare to a snow covered landscape. The snow dulls sounds so that everything is quieter than it normally is, nothing much ventures out in the cold so everything is still and calm. A feeling of peace and tranquillity seems to fall with the snow and settle over the region like a protective, mood tempering blanket. Adults become children again, throwing snowballs and making the occasional snow angel in a deep snowdrift. Everyone becomes an artist, expressing themselves through the creation of elaborate snowmen. You also get the ... (read more)
Author: Sandy Cosser
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15. Tempering Chocolate The Right Way
May 11, 2006
While tempering chocolate, it is essential that you follow the correct procedure for melting the chocolate; otherwise it may burn or separate. Many people think that tempering the chocolate is the same thing as melting it. However, even though tempering calls for melting the chocolate, the two procedures are not the same. Thus, before we get into the actual procedure for tempering chocolate, here’s a look at what tempering means.
What Is Chocolate Tempering
Tempering is a method of liquefying chocolate through a process that entails melting of chocolate, cooling it, and then again me... (read more)
Author: Bryan Hood
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16. Rice to Meet Palestinian President Abbas in West Bank
February 07, 2005
Ms. Rice says it is a time of optimism after years of bloodshed in the Middle East.
But she is tempering those remarks with reminders that fundamental steps must still be taken by the two sides to bring them back to the road map leading to a two-state solution to the conflict.
The Secretary of State, on her first visit to the region since taking office less than two weeks ago, paid a somber visit in the rain to Israel's Yad Vashem Holocaust memorial on Jerusalem's outskirts, before holding meetings with Israeli Prime Minister Ariel Sharon and Foreign Minister Silvan Shalom.
In public comments... (read more)
Author: David Gollust
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