42CrMo钢量化水淬应用研究

研究了量化水淬对42CrMo钢淬硬层深度及淬火畸变的影响,将其与普通水淬和油淬进行了比较.结果表明,量化水可以获得介于普通水和油之间的冷却特性,但300 ℃时的冷速仍明显高于油的冷速.42CrMo钢量化水淬时,可以获得介于普通水淬和油淬之间的硬化层深度和淬火硬度,量化水淬的淬火畸变也介于二者之间. 从不同试样的畸变开裂情况来看,形状复杂的42CrMo钢零件不宜采用水或量化水淬,而简单形状的42CrMo钢零件,可以根据工件的淬火要求,通过调节量化水的参数,获得所需的冷却速度,达到淬火目的.     

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。     

新型淬火介质的应用

采用新型JEF-G35淬火介质对轴承钢进行淬火冷却的实验,结果表明,采用JEF-G35淬火剂处理的轴承钢,其变形开裂倾向、淬火硬度都优于水淬和油淬,用JEF-G35代替水、油淬火是可行的,有效地解决了油淬不硬、水淬易裂的难题。     

40Cr钢量化水淬应用研究

研究了量化水淬对40Cr钢淬硬层深度及淬火畸变的影响,将其与普通水淬和油淬进行了比较。结果表明,当量化水淬的工艺参数K=3、Ts=70℃时,主要冷却特性参数分别为Vmax=93℃·s-1、V300=68℃·s-1、t200=20.5s时,40Cr钢量化水淬的冷却能力介于普通水淬和普通油淬之间,其表面硬度为58HRC、硬化层深度为4.60mm、淬火畸变平均值为0.093mm,也介于普通水淬和普通油淬之间。     

45钢量化水淬应用研究

研究了45钢量化水淬的淬硬深度和淬火畸变，并与普通水淬和油淬进行了比较分析。结果表明，调整量化水淬参数，可在水与油之间渊整水的冷却特件，使45钢得到相应的淬硬深度和较小的淬火畸变量。     

用预冷淬火减少杠杆支架畸变

图1所示杠杆支架是某武器控制系统的一个承力件,设计选材为45钢,要求淬火硬度32～37HRC。该零件由于结构复杂、壁薄厚不均,最大壁厚处13mm,最小壁厚处4mm,而且都是直角过渡。曾采用“快速淬火油”淬火、硝盐浴马氏体等温淬火,薄壁处能淬上火,但厚壁处均淬不上火;采用空-水-油预冷双液淬火,薄、厚壁部位都可淬硬53～55HRC,而且尖角处没有出现裂纹,但薄壁处畸变严重,很难校正。因此寻求一种畸变较小的淬火介质和淬火方法是解决问题的唯一途径。     

UCON E水溶液在42CrMo钢中型锻件中的应用

使用PAG类UCON E水溶液作为淬火介质,采用循环控时淬火方法,合理制定淬火冷却控时参数,解决了42CrMo钢中型尺寸锻件及其他中碳合金结构钢工件"油淬不硬,水淬开裂"的问题,工件调质后达到了技术要求的力学性能.     

量化水淬和盐水淬冷却特性及淬火畸变研究

用标准淬火介质冷却性能测试仪，系统地测试了量化淬火参数对介质冷却特性的影响，并通过45钢试样进行了量化淬火畸变的研究。试验结果表明，通过调整量化淬火参数K、Ts和Q值，可有效控制淬火介质的冷却特性，并且量化淬火试样的畸变量明显小于普通水淬和油淬试样的。     

UCON A淬火介质在结构钢工件上的应用

介绍了UCON A水基淬火介质的特性及应用实例。指出采用不同浓度的UCON A水溶液作为淬火冷却介质,应用控时控温强韧化淬火冷却技术,可解决工件油淬不硬、水淬开裂及复杂薄壁件以及细长杆件淬火畸变过大的难题。     

UCON E用于标准件的网带炉淬火

对中碳钢M8-M10标准件用网带炉进行热处理时往往被称为危险开裂尺寸。淬水易开裂,淬油易产生软点或硬度偏低,从而返修率高。长期以来,为了防止出现淬火开裂,大多数企业以油淬为主,但油淬弊端较多。第一,由于网带炉处于24h连续生产,一般新淬火油连续使用2—3个月后,明显老化,这是造成硬度偏低的主要原因。第二,淬火油是我国传统的冷却介质,但易造成环境污染,包括空气污染和水质污染。第三,淬火油安全性差,存在火灾隐患。第四,使用淬火油生产成本相对较高。为此,本试验采用美国陶氏化学公司生产的UCONE型水溶性淬火剂代替淬火油,在网带炉上对ML35钢M8-M10标准件进行淬火冷却处理,经过一年的生产试验,已取得良好的效果。     

热处理工艺对4Cr3Mo2Si1V钢组织与性能的影响

利用热膨胀相变仪测定了新型热作模具钢4Cr3Mo2Si1V的奥氏体连续冷却转变(CCT)曲线,研究了其在不同淬火、回火工艺下的力学性能和显微组织。结果表明:4Cr3Mo2Si1V钢的珠光体与贝氏体的临界冷速分别为0.03 ℃·s^-1和0.8 ℃·s^-1。经淬火试验,发现该钢种在1030 ℃和1060 ℃油淬后具有较高的硬度,且晶粒未发生明显长大。随着回火温度的提高,其硬度呈现先增后降的趋势,在500 ℃回火时由于第二相粒子大量析出,析出强化作用增强,促使二次硬化现象产生,硬度达到峰值,约57 HRC。经过多组工艺对比后,发现1030 ℃淬火和600 ℃回火后的平均冲击吸收能量达到最大值,为265 J,且硬度值仍保持在52 HRC,故最终选定1030 ℃×30 min油淬+600 ℃×2 h回火两次作为4Cr3Mo2Si1V钢的最佳热处理工艺。     

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.     

淬火温度和冷却方式对高速钢轧辊性能的影响

通过改变淬火温度和冷却方式,测定了高速钢轧辊的硬度,并测定了相应条件下对应的残留奥氏体数量;比较了油冷、雾冷和空冷条件下高速钢淬透性的大小;研究分析了不同淬火温度、不同红硬性试验温度对高速钢轧辊红硬性的影响.实验表明,选取合适的淬火温度和冷却方式,可以有效地提高高速钢轧辊材料的性能.     

合金元素Mn、Cr对SWRCH45K钢组织和性能的影响

研究了Mn、Cr含量对SWRCH45K钢组织和性能的影响。试验钢的淬火温度为860 ℃,分别进行油冷和水冷,同时利用模拟软件对淬火后硬度进行模拟计算。试验结果表明,Mn、Cr含量提高导致试验钢的抗拉强度有所增加;油冷试验钢组织均为铁素体+屈氏体,心部组织中铁素体比例略高;水冷试验钢近表面处组织为马氏体+少量的屈氏体,心部组织中屈氏体随Mn、Cr含量增加而减少。油冷试验钢硬度沿直径方向上的变化较小,0.70%Mn-0.04%Cr试验钢硬度在22~24 HRC之间,且明显低于其它试验钢;水冷试验钢近表面处硬度差异较小,心部硬度下降明显。试验结果与模拟结果对比表明,试验钢近表面处硬度值与模拟结果具有较好相符性。     

FEM modeling of induction hardening processes in steel

A modeling system for analyzing the integrated induction hardening processes was developed based on a general-purpose finite element program, with the capability to analyze the whole process from electromagnetic-induced thermal heating to final hardening. A coupled electromagnetic-thermal model was applied to study the induction heating process, which includes consideration of nonlinear material characteristics on temperature. Also, arrangement of AC current density distribution was conducted to simulate practical induction coil structure and magnetic concentrator effects to achieve desired heating patterns for later quenching and hardening analysis. Quenching analysis can provide cooling curve at any location in a heat-treated workpiece based on heat transfer principles. In hardening analysis, phase transformation was studied and an algorithm was developed to determine volumetric content of micro-structural constituents formed from austenitized phase in quenching process, based on analysis of the interaction between cooling curve and material time-temperature-transformation (TTT) diagram. Finally, hardness value was converted from martensite content based on a developed formulation. Validation was preliminary conducted based on comparison of hardening pattern of induction hardening of an automotive spindle with complex surface.     

Cooling Characteristic of Polymeric Quenchant: Calculation of HTC and Prediction of Microstructure and Hardness

The present paper discusses the influence of experimental conditions on the quenching performance of poly(2-ethyl-2-oxazoline) (PEOX) aqueous solutions used as cooling medium, using a standard ISO Inconel alloy probe for measurements of cooling rate. The evaluation procedure is demonstrated on characterization of cooling power of water-based polymer (PEOX) solutions by using different concentration, temperatures, and agitation conditions of the cooling media. The results show that the different experimental conditions have a significant effect on the cooling performance. The polymer quenching mechanism and the comparative cooling characteristics of water, and water-based PEOX polymer solution with concentrations from 2.5 to 15 wt.% were discussed. The study involved the assessment of the quenching severity by calculating the hardening power (HP) via empirical equations. Calculation of heat transfer coefficients as well as prediction of microstructural constituents and the hardness profile in a cross-section of steel sample were carried out on the basis of inverse calculation from the recorded cooling curve.     

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.     

表面淬火工艺对大型轴承套圈用42CrMo钢淬硬层的影响

对42CrMo中碳轴承钢进行不同温度中频感应加热及淬火介质的表面淬火处理,并使用洛氏硬度计、光学显微镜、扫描电镜及透射电镜对淬火试样不同区域组织及硬度进行测试分析。结果表明,经表面淬火处理后,按硬度由大到小试样可分为淬硬区、过渡区及基体3个区域,随着表面淬火加热温度的升高,表面淬硬层的深度增加,并且相对于水淬,油淬的淬硬层深度显著减少。组织分析表明,水淬淬硬区组织均为马氏体,而油淬工艺由于冷速较慢,淬硬层组织为马氏体+铁素体组织,不同表面淬火工艺条件下过渡区组织均为马氏体+回火索氏体,基体为原始调质态的回火索氏体。淬硬区、过渡区及基体的组织差异导致不同区域的硬度差异。实际应用中应根据所需淬硬层深度选择合适的水淬加热温度。     

Effect of hardening conditions on mechanical properties of high speed steels

Abstract

Hardness and toughness are the main properties determining wear resistance and performance of high speed steel tools. The objective of the present paper was to study the effect of hardening conditions on the toughness of high speed steels, mainly concerning the hardening temperature and cooling rate during quenching. Several conditions were simulated in laboratory and industrial heat treatment furnaces and toughness was evaluated through the static bend test. Under the same tempering condition, the higher the hardening temperature, the higher the attained hardness. The results also point out a compromise situation between hardness and toughness, until 1200°C hardening temperature is reached; for temperatures over this value, the loss in toughness become more accentuated, without a considerable increase in hardness. The present paper also describes the mechanical properties of M2 high speed steel heat treated to lower hardness, necessary in some cold work tooling applications. In this case, hardening at lower temperatures and tempering close to the peak hardness has shown the best results. And lastly, regarding cooling conditions during nitrogen hardening in a vacuum furnace, the results point out that low quenching pressures might reduce the cooling rate and decreases material toughness, but the differences are very small for pressures between 6 and 9 bar.