【正文】 ing of steel to a temperature below the transformation temperature, as in tempering, but is done primarily to relieve internal stress and thus prevent distortion or cracking during is sometimes called process Tempering consists of reheating a quenched steel to a suitable temperature below the transformation temperature for an appropriate time and cooling back to room this process makes steel tough will be discussed Hardening is carried out by quenching a steel, that is, cooling it rapidly from a temperature above the transformation is quenched in water or brine for the most rapid cooling, in oil for some alloy steels, and in air for certain higher alloy steel is quenched, it is usually very hard and brittle。Refine the grain structure of hot worked steels which may have developed coarse grain size。Decrease the hardness and increase the ductility。that is, to produce a steel having both a high tensile strength and good ductility, enabling it to withstand high impact。Improve the machinability。 higher temperatures are employed, toughness or shock resistance of the steel is increased, but the hardness and strength is the ability of a metal to change shape before it quenched martensite is hard but not ductile。Biomass gasification in supercritical water(SCW超臨界水)is a promising technology for Hydrogen production from biomass, which is based on the special physical and chemical properties of water near the critical point.第三篇：過(guò)程裝備與控制工程專(zhuān)業(yè)專(zhuān)業(yè)英語(yǔ)翻譯9Reading Material 9Heat Treatment of SteelTypes of Heat Treating OperationsFive operations are detailed in this lesson as the basis of heat of theseOperations RelievingWhen a metal Is heated，expansion occurs which is more or less proportional to the temperature cooling a metal,the reverse reaction takes is, a contraction is observed．When a steel bar or plate is heated at one point more than at another，as in welding or during forging，Internal stresses are set up．During heating, expansion of the heated area cannot take place unhindered，and it tends to deform．On cooling，contraction is prevented from taking place by the unyielding cold metal surrounding the heated area．The forces attempting to contract the metal are not relieved，and when the metal is cold again，the forces remain as internal stresses．stresses also result from volume changes, which acpany metal transformations and precipitation．Internal or residual stresses are bad because they may cause warping of steel parts when they are machined．To0relieve these stresses，steel is heated to around 595C，assuming that the entirepart is heated uniformly, then cooled slowly back to room temperature．This procedure is called stress relief annealing, or merely stress of characteristics inherent in cast steel, the normalizing treatment is more frequently applied to ingots prior to working，and to steel castings and forgings prior to process of normalizing consists of heating to a temperature above the third transformation temperature and allowing the part to cool in still actual temperature required for this depends on the position of the steel,0but is usually around , the term normalize does not describe the process might be more accurately described as a homogenizing or grainrefining any piece of steel, the position is usually not uniform is, one area may have more carbon than the area adjacent to positional differences affect the way in which the steel will respond to heat it is heated to a high temperature, the carbon can readily diffuse throughout, and the result is a reasonably uniform position from one area to the steel is then more homogeneous and will respond to the heat treatment in a more uniform cold deformation, steel has a tendency to harden in deformed areas, making it more difficult to bend and liable to deforming and annealing operations are performed on most manufactured steel annealingFull annealing, where steel is heated 50 to 100C above the third transformation temperature for hypoeutectoid steels, and above the lowest transformation temperature for hypereutectoid steels, and slow cooled, makes the steel much easier to cut, as well as full annealing, cooling must take place very slowly so that a coarse pearlite is cooling is not essential forprocess annealing, since any cooling rate from temperatures below the lowest transformation temperature will result in the same microstructure and annealingProcess annealing consists of heating steel to a temperature just below the lowest transformation temperature for a short makes the steel easier to heat treatment is monly applied in the sheet and wire industries, and the temperatures generally used are from 550 to The twostage heat treating process of quenching and tempering is designed to produce high strength steel capable of resisting shock and deformation without the other hand, the annealing process is intended to make steel easier to deform or manufacturing steel products, machining and severe bending operations are often tempered steel may not cut or bend very easi1y and annealing is often effect of tempering may be il1ustrated as the head of a hammer were quenched to a fully martensitic structure, it probably would crack after the first few during manufacture of the hammer imparts shock resistance with only a slight decrease in is acplished by heating a quenched part to some point below the transformation temperature, and holding it at this temperature for an hour or more, depending on its steels are tempered between 205176。王局長(zhǎng)：Hydrogen production from biomass can contribute not only to largescale development and utilization of renewable energy, improve energy structure and reduce pollution as well as to meet people39。Thus, a bined cycle plant can be designed that uses the hot flue gases produced from organic waste bustion to generate steam and gasify liquid methane in stages to turn a steam turbine and a gas turbine respectively , and the flue gases, cooled down, can be used to pre