Design of Quenching Process for Large-sized AISI P20 Steel Block Used as Plastic Die

For large-sized AISI P20 steel block used as plastic die with a thickness of more than 200 mm, appropriate quenching processes are the key to obtain much thick hardened layer. In this paper, different quenching processes of AISI P20 steel block such as oil quenching, direct water quenching, water quenching with precooling and water quenching with pre-cooling and self-tempering were numerically investigated by computer simulation based on the detailed discussion on the mathematical models of quenching processes including partial differential equations of heat transfer, thermal physical properties, latent heat, heat transfer coefficient and calculation of phase transformation, The results show that the water quenching with pre-cooling and self-tempering process can not only effectively avoid quenching cracks, but also obtain deeper harden depth than oil quenching.

Numerical and experimental analysis of quenching process for cam manufacturing

In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology.

Effects of Quenching Process on Microstructure and Mechanical Properties of Low Carbon Nb-Ti Microalloyed Steel

The low carbon Nb-Ti mieroalloyed tested steel was prepared by the process of vacuum induction furnace smelting, forging and hot rolling. The new steel aims to meet the demand of high strength, high toughness and high plasticity for building facilities. The effects of quenching process on microstructure and mechanical properties of tested steel were investigated. The results showed that prior austenite grain size, phase type and precipitation behavior of （ Nb, Ti） （ C, N） play important roles in mechanical properties of the steel. Through modified appropriately, the model of austenite grain growth during heating and holding is d^5.7778 = 5. 6478^5.7778 ＋ 7.04 × 10^22t^1.6136 exp（- 427. 15 ×10^3 /（RT））. The grain growth activation energy is Qg = 427. 15 kJ. During quenching, the microscopic structures are mainly martensite and lath bainite which contains lots of lath substructure and dislocations. The content of phases, fine and coarsening （ Nb, Ti ） （ C, N ） precipitated changes during different quenching temperatures and holding time. Finally compared with the hardness value, the best quenching process can be obtained that heating temperature and holding time are 900 ℃ and 50 mins, respectively.

Structure and electrochemical properties of hypo-stoichiometric hydro-gen storage alloys prepared by twin-roller rapid quenching process

The stoichiometric alloy MlB5.0 and the hypo-stoichiometric alloy MlB4.85 were prepared by twin-roller rapid quenching process, and their structure and electrochemical properties were studied. The results of XRD show that both of the alloys have a typical single-phase hexagonal CaCus-type structure. The cell volume of the hylpo-stoichiometric alloy M1B4.85 is slightly larger than that of the stoichiometric alloy M1B5.0, although its lattice constant cla is smaller. Under 2 C discharging rate, i.e. 640 mA/g, the M1B4.85 has a discharge capacity of 320 mAh/g, which is higher than that of the M1Bs.o, 312 mAh/g. Nevertheless, the capacities of the M1B4.85 and the M1Bs.o decline 24.7% and 20.2% after 400 cycles, respectively. The relationship of electrochemical performances of the alloys with their structures is discussed.

A New Quenching Process and Tower to Improve the Recovery of Acrylonitrile

Quenching process and design of the quenching tower in acrylonitrile production in China were studied in order to decrease the polymerization loss of acrylonitrile in the quenching tower. Based on the research of acrylonitrile polymerization in the quenching tower, a new quenching process was proposed to avoid the disadvantages of the original process. Two kinds of internals were installed to improve the performance of the quenching tower. Through a series of air-flow and real-flow model experiments, the new quenching process and new design were showed to be successful in enhancing the mass and heat transfer in the vapor-liquid system and decreasing the loss of acrylonitrile.Industrial application showed satisfactory results of decrease of the acrylonitrile loss in the quenching tower by about 4.5% and increase of the acrylonitrile recovery of the whole plant by more than 4%.

Component modification of steel slag in air quenching process to improve grindability

A new solution called component modification in-process was introduced to the difficult grinding of air quenching steel slag by a series of experiments. The results show that the fly ash added into the molten steel slag before air quenching can more effectively improve the slag's grindability than milltailings, which is the other modification agent tested under the same conditions. The role of fly ash is strengthened as its proportion increases, although the degree of promotion is gradually reduced. As a result of the reaction between fly ash and steel slag at high temperature, some new mineral phases and vitreous bodies with fine grindability promote the slag grinding easily. This work is helpful to making a comprehensive utilization of steel slag and maximize its economic efficiency in China.

Effect of supply voltage and body-biasing on single-event transient pulse quenching in bulk fin field-effect-transistor process

Charge sharing is becoming an important topic as the feature size scales down in fin field-effect-transistor （FinFET） technology. However, the studies of charge sharing induced single-event transient （SET） pulse quenching with bulk FinFET are reported seldomly. Using three-dimensional technology computer aided design （3DTCAD） mixed-mode simulations, the effects of supply voltage and body-biasing on SET pulse quenching are investigated for the first time in bulk FinFET process. Research results indicate that due to an enhanced charge sharing effect, the propagating SET pulse width decreases with reducing supply voltage. Moreover, compared with reverse body-biasing （RBB）, the circuit with forward body-biasing （FBB） is vulnerable to charge sharing and can effectively mitigate the propagating SET pulse width up to 53% at least. This can provide guidance for radiation-hardened bulk FinFET technology especially in low power and high performance applications.

Numerical simulation research of dimension variation in heavy plate during quenching and tempering process

The dimension variation of B610E steel during the quenching and tempering process was simulated by ABAQUS,the coefficient of heat transfer during quenching was verified by the buried thermocouple test and the trend of the dimension variation during the quenching process was also calculated by ABAQUS. It was shown by the comparison of simulated results and industrially measured results that only the simulation of thickness and width variation was accurate, while length variation needed further simulation. Besides, the dimension variation trend was identical with the measured results.

Flame quenching process in cavity based on model scramjet combustor

The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the flame and shock structure in the combustor was clearly observed. The results revealed that the precom- bustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while. The time of quenching process was extended by the cavity flame holder, and the ability of flame holding was enhanced by arranging more cavities in the downstream as well. The flame was blown from the upstream to the downstream, so the flame in the downstream of the cavity was quenched out later than that in the upstream.

CFD simulations of quenching process for partial oxidation of methane:Comparison of jet-in-cross-flow and impinging flow configurations

A new quenching process using the cold pyrolysis gas has been proposed for the partial oxidation(POX) of methane to recover the heat. The mixing of hot product gas and cold pyrolysis gas in milliseconds is critical to this new approach. Two most widely-used rapid mixing configurations, i.e. the jet-in-cross-flow(JICF) and impinging flow configurations, are compared in terms of mixing and quenching performances using computational fluid dynamics(CFD) coupled with detailed reaction mechanism Leeds 1.5. The mixedness, residence time distribution, temperature decreasing rate and loss ratio of acetylene during the quenching are systematically studied. The results show that the impinging flow has a more uniform mixing and narrower residence time distribution than the JICF.However, the temperature decreasing rate of the mainstream is faster in the JICF than in the impinging flow. The loss ratio of acetylene in the quenching process is 2.89% for the JICF and 1.45% for the impinging flow, showing that the impinging flow configuration is better and feasible for the quenching of POX of methane.

Design of Industrial Quenching Processes

The method of designing industrial processes of quench cooling, in particular, the speed of the conveyor movement with regard to shape and sizes of parts to be quenched, thermal and physical properties of material and cooling capacity of quenchants has been developed. The suggested designing method and databases are the basis for the complete automation of industrial processes of quench cooling, especially for continuous conveyor lines, with the purpose of making high-strength materials. The process is controlled by infrared technique.

Effects of Chemical Composition and Cooling Process on Structures and Properties of Direct-Quenched Steels

The microstructures and mechanical properties of a series of direct-quenched steels containing,in weight percent,from 0.05 to 0.20 carbon,0.20 to 0.40 silicon,1.10 to 1.70 manganese and at least one microalloying element of vanadium,niobium,titanium and boron have been investigated.After controlled rolling,these steels were cooled in spray water to 400,300 and 200℃,respectively and then cooled in still air.Comparison of the Charpy V-notch impact toughness of direct-quenched steels without subsequent tempering was made with that of direct-quenched steels tempered at 600℃.It is found that an attractive combination of strength and toughness is achived by means of direct-quenching.There exists two types of microstructures in accordance with carbon equivalent.Lath martensitic microstructure is obtained for C>0.4%,granular bainitic microstructures for C.< 0.35%and mixtures of martensite and bainite for C,.in the range of 0.35— 0.40%.The effect of interrupted quenching temperature on microstructure is not significant for low C.steel,but interrupted quenching temperature has a strong effect on microstructure for high C,.steel.

退火温度对淬火配分后热轧高强钢显微组织和力学性能的影响

将热轧高强钢升温至不同温度(780,810,840,870℃)保温退火600s后进行200℃×60s淬火+410℃×300s配分处理,研究了退火温度对其显微组织和力学性能的影响。结果表明:随着退火温度升高,淬火配分后试验钢中铁素体和马奥岛含量减少,回火马氏体、残余奥氏体和贝氏体含量增加;随着退火温度升高,抗拉强度先减小后增大,屈服强度、断后伸长率、屈强比和冲击吸收功均先增大后减小;840℃退火温度下淬火配分后试验钢的强度、塑性和韧性匹配优异,抗拉强度(830MPa)较大,屈服强度(585MPa)、断后伸长率(39.6%)、屈强比(0.70)和冲击吸收功(-20,-40℃环境下分别为28.35,27.69kJ)最大。

GCr15SiMo钢中贝氏体含量对力学性能及干摩擦磨损性能的影响

目的通过控制等温淬火时间,在GCr15SiMo轴承钢中获得不同含量的贝氏体组织,并研究不同含量的贝氏体组织对材料力学性能和干摩擦磨损性能的影响。方法采用SEM、3D morphology、TEM、EDS、XRD、洛氏硬度计、冲击试验机等仪器观测GCr15SiMo轴承钢经不同等温淬火时间后的微观组织、物相含量和力学性能,并使用HL-R7000重载往复摩擦磨损试验机对不同贝氏体组织含量的试样进行摩擦磨损性能检测。结果当等温淬火时间由2 h延长至72 h时,材料中贝氏体的体积分数由14.5%增至83.5%。随着GCr15SiMo轴承钢材料中韧性贝氏体含量的增多、脆性马氏体含量的减少,其硬度逐渐降低,冲击功逐渐增大,磨损率呈现先降低再升高的趋势。材料的磨损机制主要为黏着磨损和磨粒磨损,随着等温淬火时间的延长,基于韧性贝氏体含量的增加,材料的磨粒磨损减弱、黏着磨损增强。结论在等温淬火温度为210℃、等温淬火时间为8 h时,材料中贝氏体的体积分数约为55.6%,马氏体的体积分数为33.2%,此时马氏体和贝氏体复相组织具有良好的强韧性匹配,材料的耐磨性能较好。

工艺条件对40 kg焦炉试验结果的影响研究

40 kg试验焦炉是评价炼焦煤成焦特性的常用设备,利用40 kg焦炉通过正交实验考察炼焦、备煤、熄焦工艺条件对试验结果的影响,结果发现:炼焦初温800℃、炼焦终温1050℃、恒温时间6 h为较优的炼焦工艺条件;<3 mm粒级比例为85%~90%、<0.5 mm粒级比例不高于30%、入炉煤水分10%、堆密度800 kg/m^(3)为较优的备煤工艺条件;熄焦水用量13.5 kg、熄焦时间5 min为较优的熄焦操作条件。

淬火工艺对A514CrQ齿条钢显微组织演变及硬度的影响

研究了淬火工艺对A514CrQ齿条钢组织演变及硬度的影响及机理。结果表明,经790℃/30 min水淬后得到粒状贝氏体+少量板条马氏体。经820~950℃/30 min水淬后得到全板条马氏体,且随淬火温度升高马氏体板条块宽度增大,硬度逐渐下降,得到820℃为最优淬火温度。在820℃保温1~5 min后水淬获得粒状贝氏体+板条马氏体组织,硬度较低;保温10~70 min后水淬获得全板条马氏体组织,且随保温时间延长马氏体板条块宽度增加,硬度逐渐下降并趋于持平,得到10 min为最优保温时间。经820℃/10 min空淬、油淬后均获得粒状贝氏体+板条马氏体/贝氏体组织,且油淬的马氏体/贝氏体含量更高。这导致空淬的硬度最低,油淬的居中,水淬的硬度最大。在双次循环淬火过程中,二次淬火介质决定了最终组织,且以水为一次淬火介质可更有效细化马氏体/贝氏体板条块。820℃/10 min水淬+820℃/10 min水淬的马氏体板条块最细小,硬度最高,可作为该齿条钢的优选淬火工艺。

深层页岩气用高强度套管强韧性研究

为满足井深大于3 500 m的页岩气开发用高强度套管的强韧性要求,对试验用套管钢在不同热处理条件下的强韧性变化、显微组织演变及微观断裂机制等进行试验研究。试验结果表明:该试验钢的最佳热处理工艺条件为920℃保温45 min后淬火,660℃保温60~90 min后回火,其屈服强度≥1 000 MPa、-10℃横向冲击功≥80 J,可满足T/CPSI 01301—2022标准对140钢级的要求,具有最佳的强韧性匹配。随着回火温度升高及回火保温时间延长,晶界、板条内及板条界等位置上析出碳化物发生球化、聚集及粗化演变,断口形貌特征逐渐转变为准解理、撕裂棱及二次裂纹,进而演变成大小韧窝和少量二次裂纹特征,造成了试验钢的强韧性差异。

干煤粉气化激冷流程工艺运行分析及优化措施

介绍了国能集团宁夏煤业有限责任公司400万t/a煤间接液化项目干煤粉气化激冷流程的工艺流程。针对气化炉激冷流程工艺系统运行时存在的合成气带水、带渣、带灰等问题,经分析认为主要原因是激冷室液位控制不当、合成气洗涤塔塔盘冲洗水水质差且塔盘结构设计不合理;为此,进行了相应的结构、材料、管线等方面的技改优化。运行效果表明:改造后合成气带水、带渣、带灰等问题得到了有效解决,合成气洗涤塔塔盘压差趋于平稳。

涤纶POY/FDY复合丝环吹风冷却工艺探讨

以特性黏数0.65~0.68 dL/g的聚对苯二甲酸乙二酯熔体为原料,采用环吹风冷却方式,以两对热辊拉伸生产135 dtex/128 f涤纶预取向丝(POY)/全拉伸丝(FDY)复合丝,探讨了在环吹风冷却下无风区的设置、冷却工艺等对复合丝性能的影响。结果表明:在缓冷加热器温度为290℃,无风区高度为120~140 mm,环吹风压力为30~40 Pa,风筒高度为185 mm的较佳环吹风冷却工艺条件下,生产的涤纶POY/FDY复合丝品质较好;相比侧吹风冷却方式,环吹风冷却方式生产的复合丝的条干不匀率变异系数下降38.9%,产品优等品率提高3.2%,毛丝降等率下降22.1%。

风淬高钛矿渣制备及其性能

自然冷却或水淬急冷高钛矿渣熔体预处理工艺存在显热全部流失、现场环境恶劣、产品附加值低等问题。利用自主搭建的熔融-风淬实验装置制备了风淬高钛矿渣,并研究了其物理化学特性。结果表明:风淬可有效实现高钛矿渣急冷粒化、矿物重构和粒形重塑,过程热风也更容易回收利用;风淬高钛矿渣颗粒粒径主要分布在4.75 mm以下且多呈球形,矿物组成以无定形玻璃体为主,其颗粒表面致密光滑、压碎值低、堆积空隙率低;以筛分风淬高钛矿渣代替标准砂制备了水泥胶砂,当水胶比为0.41和0.38时,新拌胶砂工作性和28 d力学性能与标准砂制备的水泥胶砂相当。风淬高钛矿渣具有作为功能辅助集料的应用前景。