动态淬火介质冷却特性及换热系数的研究

为了研究工业生产条件下淬火油在不同流速下的冷却特性曲线及换热系数 ,用超声波多普勒流量计测定了淬火油槽的流速 ,按ISO9950标准测定冷却特性曲线 ,用 1 2 0mm× 1 2 0mm× 2 0mm平板状试样和反传热法测定与计算了换热系数。结果表明 ,随着介质流速的增加冷却特性曲线的冷速最大值及换热系数的最大值均呈增加趋势 ,当搅拌使介质中产生气泡时 ,介质的冷却能力明显降低。最后指出换热系数曲线能更好地反映表面热量传递的真实情况。     

淬火介质和淬火槽的冷却能力

前言不言而喻,钢淬火时的冷却方法是一重要因素。淬火介质中使用较多的是油和水,但近来也开始采用水溶性淬火介质和热浴等。淬火介质的冷却能力可用其冷却速度进行比较,通常以淬火烈度H来定量地表述。然而,尽管是比较出了淬火介质本身的冷却能力,     

银探头测定淬火油淬火烈度的新方案(法)

(方案№4,1982.4)用以置代并废除1979.12原有方案说明:在法国和其他国家都发展应用圆柱形银探头测试淬火烈度。因此,本文所规定的操作条件对于“淬火介质”工作组的成员显得十分重要。当然今后将根据使用者经验和认识的变化将重新予以修改。 1.目的和应用范围本文的目的在于说明一种测定铁合金淬火油淬火烈度的试验方案。 2.淬火烈度的定义: 金属加热至油的沸点温度以上,淬火油对淬火冷却能力称为油的淬火烈度。 3.试验原理: 以圆柱形银探头中心连接热电偶所组成的探头,加热至800℃后,随即浸入试验油样中。热电偶记录探头中心在冷却过程中的温度变化与时间或冷却速度的关系曲线。     

水,油等淬火介质淬硬能力的数值评价方法

本文论述了以淬火硬度评定水、油及冷却特性介于水油之间的淬火介质淬硬能力的方法。其基本思路是,钢的连续冷却转变图中的每条曲线代表着钢的某一硬度,反之也可以认为淬火硬度也对应着该图的某一条曲线,代表介质的淬硬能力,从而就可以借助于淬火硬度值来评定水、油等淬火介质的淬硬能力。     

油污掺杂对PAG水基淬火液冷却特性的影响

为了探究油污对水基型淬火液冷却性能的影响,测试了不同油浓度下淬火液的冷却速率曲线、硬化能力等,通过分析淬火的具体过程和特性值函数,探讨了油污的掺杂影响淬火液冷却性能的机制。结果表明:当淬火液中油污含量大于0.3%时,淬火液的冷却性能明显变差,具体表现为沸腾阶段延后且高温阶段冷却速率明显下降,淬火液的硬化能力也随之降低;但油污的含量对工件的畸变影响较小。     

水在不同温度和流速下冷却能力的测量

为了研究水在不同温度和不同流速下的冷却特性,采用标准镍合金探头和淬火介质动态冷却特性测定仪,分别对水在不同温度和不同流速下的冷却曲线进行了测量,并对其冷却特性进行了定性分析和定量计算.结果表明:水温变化对水的冷却能力的影响明显高于流速变化对其的影响;静止水在水温60～70℃区间的冷却能力发生突变;水温和流速对水的冷却能力的影响可以用硬化能力值和冷却曲线面积定量表示.     

淬火介质冷却能力的测定和应用

从传热学角度对淬火冷却过程进行了分析，探讨了淬火介质冷却能力和硬化能力的区别，简要总结和评价了淬火介质冷却能力的几种主要测定方法，对目前广泛的冷却曲线测定方法，给出了应用实例并就应用时应注意的问题提出了建议。     

利用常用钢热探头建立淬火冷却介质数据库

使用GCr15和H13等10余种常用钢制造新型热探头来评价淬火介质的硬化能力。测量了若干淬火介质淬火过程冷却曲线，研究了热探头淬后截面的微观组织和硬度分布。在此基础上开发的淬火介质冷却能力数据库，可以实现淬火过程冷却曲线和冷速曲线及热探头淬后组织和性能的查询和输出，且可存储热探头淬后开裂数据。     

等温淬火油用于齿轮的淬火冷却

测定了HSFD型等温淬火油和N32机械油的件能指标和冷却特性曲线.通过两种用于齿轮淬火冷却的淬火介质的对比实验分析,讨论了淬火介质的冷却特性对齿轮性能和尺寸变化的影响.结果表明,HSFD型分级等温淬火油可以起到替代N32机械油的作用,并成功地用于齿轮生产,齿轮经热处理后.不仅组织结构、力学性能可以满足要求,而且可以减小齿轮变形.     

淬火介质换热系数绵计算机测算

提出了用计算机进行测量和计算淬火过程中淬火介质换热系数的反传热模型。该模型利用采样系统测得的上结位置的冷却曲线来计算淬火介质的换热系数，获得其随表面温度变化的曲线，对水和油的测算结果表明，计算值和实际情况吻合较好。     

Challenges to Introduce Advanced Cooling Technology by the Utilization of Plural Cooling Velocity

The control of cooling power is very important to introduce desired properties. Usually, higher the cooling rate higher the quench hardness and distortion and the optimization of cooling power is the base for good heat treatment. The change of cooling speed during quenching is one of the effective methods to balance hardness and distortion. Different form the general knowledge of the demerit of vapor blanket stage, oil with long vapor blanket stage is also one of effective methods to reduce distortion. The reduction of distortion with enough quench hardness seems to be possible by optimization of cooling condition by the help of computer simulation. The exhibition of higher core hardness than surface in through hardening steels experienced in the “Inverse quench hardening” was introduced by Prof. Tamura and Shimizu. This mechanism is well explained by Arimoto et al, by analysis of computer simulation. In this paper, plural steps cooling methods are compared, in relation with cooling curve and heat transfer coefficient that is necessary to simulate quench results and the possibility of advanced cooling technology is discussed.     

三维点式感应淬火电磁热耦合场数值模拟

针对45钢三维点式感应淬火工艺进行参数设计,建立点式感应淬火过程的电磁场及温度场的非线性偏微分方程组,在有限元软件ANSYS中使用耦合场分析的方法实现了对加热功率为36 kW,电流频率为50 kHz的感应热处理工艺的数值模拟.结果表明,在综合考虑表面组织完全奥氏体化及感应加热效率的情况下,该工艺的最佳加热时间约为2 s.通过模拟分别得到使用冷却水和冷却油作为冷却介质时的感应淬火过程中的温度变化规律,结合45钢的连续冷却转变曲线,以马氏体转变临界冷却速度为判断依据,对淬火后工件表面组织进行预测,结果表明两种淬火条件均可以实现表面组织马氏体转变,实现工件的表面强化,且淬硬深度均约为1.0 mm.     

Cooling Curve''''s Effect on Hardening Behavior of Steel

TO QUENCH HARDEN STEEL MATERIAL,it isrequired to give rapid quenching in the temperaturerange required of rapid quenching.On the other hand,quenching oil comprised of mineral oil as majorcomponent can be modified of its cooling curve byusing various additives.Thereby,we havequench-hardened some steel material each havingdifferent pattern of CCT curve,using quenching oilcomprised of mineral oil modified of coolingcharacteristics by dosing additives,and surveyedrelationship between ha…     

Effect of thermal conductivity and viscosity on cooling performance of liquid quench media

Abstract

In this present work, the effect of the thermophysical properties of quenchants on its cooling performance was investigated. Water, brine solutions, polymer solutions and mineral oils were chosen to have quench media with varying thermophysical properties. Cooling curve analyses were carried out by using standard ISO/DIS 9950 quench probe. Grossmann H quench severity of the quench media was determined from the relation of H and cooling rate. Cooling curve analysis results showed that the change in thermophysical properties of the quench media had significant effect on the cooling history of the quench probe. The viscosity of the quenchant used for immersion quenching is the most important factor that controls the cooling performance of the quenchant compared to thermal conductivity of the quench medium.     

Heat transfer during quenching of modified and unmodified gravity die-cast A357 cylindrical bars

Heat transfer during quenching of chill-cast modified and unmodified A357 Al-Si alloy was examined using a computer-aided cooling curve analysis. Water at 60 °C and a vegetable oil (palm oil) were used as quench media. The measured temperatures inside cylindrical probes of the A357 alloy were used as inputs in an inverse heat-conduction model to estimate heat flux transients at the probe/quenchant interface and the surface temperature of the probe in contact with the quench medium. It was observed that modified alloy probes yielded higher cooling rates and heat flux transients. The investigation clearly showed that the heat transfer during quenching depends on the casting history. The increase in the cooling rate and peak heat flux was attributed to the increase in the thermal conductivity of the material on modification melt treatment owing to the change in silicon morphology. Fine and fibrous silicon particles in modified A357 probes increase the conductance of the probe resulting in higher heat transfer rates. This was confirmed by measuring the electrical conductivity of modified samples, which were found to be higher than those of unmodified samples. The ultrasound velocity in the probes decreased on modification.     

控时浸淬系统（ITQS）原理及在周期式和连续式生产中的应用

淬火过程中,控制搅拌的方向和程度可减少钢淬火时的变形、开裂及获得高的硬度和均匀性。理想的情况,是在淬火开始阶段增大淬火烈度以获得高硬度,当钢件温度接近Ｍｓ点时,降低淬火烈度以减小工件的变形和开裂倾向。在整个淬火过程中,影响淬火烈度且最易改变的工艺参数是搅拌。如果搅拌速率可根据要求连续变化是最理想的。本文阐述了计算机控制的“控时浸淬系统（ＩＴＱＳ）”原理以及ＩＴＱＳ目前在热处理中的应用。并探讨ＩＴＱ     

211Z高强韧耐热铝合金的淬透性研究

采用类端淬设备、电导率计、差示热扫描分析仪和透射电镜等并结合数字模拟研究了211Z型铝合金的淬透性能。结果表明:试样在≤40℃水温淬火的过饱和固溶程度、时效后的硬度均高于水温较高(50~60℃)时淬火的相应值,但淬透深度相反;试样时效处理后的硬度值受淬火敏感温度区间(140~380℃)的平均冷却速度影响,超过临界值后,硬度值基本保持不变,小于临界值,则随平均冷却速度的增加而增大。     

评价淬火介质换热特性的Grossmann法与集中热容法的比较

研究了用于估算纳米流体、盐水溶液和某洗涤剂基试验介质淬火烈度的Grossmann法和集中热容（ LHC）法的适用性,评价了探头截面厚度对不同淬火介质换热系数的影响。借助于计算机分析了304不锈钢探头在淬火过程中的冷却曲线,并分别采用Grossmann法和LHC法对所测得的冷却曲线进行了换热系数的估算。研究表明,采用矱10 mm不锈钢探头的LHC法适用于淬火烈度小于20 m-1介质的表征。虽然Grossmann法是基于平均换热系数这一假设的,但仍能应用于具有不同淬火烈度介质之间的评定。 Grossmann法能更敏感地反映探头截面厚度对换热的影响。