Development of New Sliver Probe for Cooling Power Test of Polymer Quenchants

Working group on cooling power test of quenchants of Japanese Heat Treatment Society hits studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new sliver rod probe, which has a metal-sheathed thermocouple at its geometrical center. The experimental study has clarified that the new silver probe has more excellent durability than the JIS silver probe employed for cooling power test of heat treating oils (JIS K 2242) and an aluminum alloy probe. Good repeatability, and reproducibility of the cooling curves during polymer quenching have been confirmed. This new method is useful especially for cooling power test of aqueous quenchants used for solution heat treatment of aluminum alloys. This new silver rod probe is expected to be adopted for the revised version of JIS K 2242 as the cooling power test method for aqueous quenchants.     

淬火剂冷却性能的测试

论述了按照JB/T7951-2004《测定工业淬火油冷却性能的镍合金实验方法》和SH/T0220-92《热处理油冷却性能测试方法》测定淬火油和水溶性淬火剂的冷却性能的方法,其中包括测试中的一些关键点,例如探头的标定、打磨、清洗和电磁干扰的影响,热电偶的线性补偿,淬火油冷却性能的评定,以及注意事项等。     

Quenchant Characterization System Based on Application of Thermal Probes of Typical Steels

A system was developed to identify characteristics of quenchants. It consists of computerized hardware,temperature acquisition software as well as changeable probes of steels. The feature of the ability to use probes made of any metallic material enables evaluation of hardening power of quenchants. Three thermal couples located on the same cross-section plane in the middle of probe‘s length give cooling curves that present cooling behavior at different depths from the surface of probe. Microstructure and hardness of the quenched probes on the same plane in the middle of probe‘s length from surface to center was investigated to estimate hardening effect. A number of quenchants were tested by this characterization system with several thermal probes of typical steels. Experimental data were stored in QuenDB quenchant database, which was designed for quenchants identification and hardness distribution storage.     

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.     

Effect of composition on oil quenchant performance

Abstract

Quenching is the most common method of hardening metals and involves continuous cooling from a given austenitising temperature to achieve full transformation into a martensitic structure. The cooling rate depends mainly on the thermal characteristics of the metal, the section thickness of the workpieces and the heat removal properties of the quenching medium. Oils, when used as quenching media contain a base oil and different types of additives according to the application requirements. As the base oil, it is possible to use mineral, synthetic and natural oils, either separately or in combination. Mineral base oils are widely used because of their advantages in stability in comparison with natural oils, or lower price in comparison with synthetic oils. There are numerous additives available for use but, besides functional properties, the environmental and safety requirements have to be considered in their selection, e.g. barium additives must be replaced with less harmful compounds. Additionally, petroleum derivatives should be replaced by renewable base stocks that are biodegradable, which is a general trend in lubricant development. By changing the composition of the base oils and additives, heat transfer characteristics are also changed. This study presents the results of the analysis of physical and chemical properties, as well as of cooling characteristics of new quenching oils with different compositions. Cooling curves have been evaluated according to ISO 9950 standard.     

Numerical Methods for Safeguarding the Performance of the Quenching Process

A new numerical technique for testing and evaluation of quenching media and quenching systems is outlined. The measured time-temperature samples as a result of cooling curve test are analyzed by the new software developed, in order to characterize quantitatively the quenchants. The method applied is based on Fourier analysis. Examples for evaluation and comparison of cooling performance of quenchants are presented the applicability of the computational technique.     

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。     

新型淬火剂SST201冷却特性研究

本文简述了淬火剂SST201的基本特性,并对其冷却特性进行了探讨。结果表明:SST201的冷却能力随其浓度增大,温度升高,重复使用次数增多而降低,并揭示了该介质在冷却金属时能在金属表面形成一层聚合物隔离膜,此膜能避免因零件的几何形态的差异造成的冷却不均匀现象,有效地防止开裂与变形。     

淬火油的淬火烈度分类

钢的淬火是最常见的热处理工艺之一，淬火的目的是为了获得马氏体组织，使之具有优良的硬度和强度。最常见的淬火介质有水溶液、聚合物溶液和矿物油。在整个淬火剂市场中，估计矿物油占了80％的份额。在巴西，人们对淬火油及其冷却特性的了解不够，因此作者试图确定淬火油的适用性及其分类。     

植物油的氧化及其对淬火特性的影响

传统上,矿物油是常用淬火剂中最重要的一类淬火剂。然而,它们在本质上缺乏环保性,又有毒性,再从长期低价供应角度考虑,有必要寻找新的替代介质。石油制品油的淬火特性与其成分很有关系,因而受其氧化降解性能的限制。由于不断暴露在钢与油接触面问相对较高的温度中,石油制品油遭受热降解和氧化降解,使得其淬火特性发生明显变化。因此,淬火特性是任何一种可选择的淬火介质都必须要检验的一个非常重要的性能参数。可供选择的一类液态物质为植物油,它们具有典型的生物降解特性并且无毒。然而,植物油具有相对较差的抗氧化稳定性能,因此测定氧化对其淬火特性的潜在影响具有重要意义。本文报导的结果仅是这项巨大研究中的第一步,在这项工作中,对不受禁止的植物油的试验是在实验室设备上进行的,以前报告的促使石油制品油早期氧化的过程接近实际使用条件。依照ASTM D 6200标准,使用粘度计、红外线分光镜、^13CMR分光镜以及冷却曲线特性测定方法对所研究的液态植物油进行了性能检测并和典型的石油制品油作了成分比较。所得的结果表明,作为淬火介质,植物油是有前景的石油制品油的替代品,但在商业上要可行,同时必须使用适当的抗氧化剂。     

淬火介质换热系数的计算机测算

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探头上某些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．     

冷却过程的动态特性与钢的实际淬火冷却

采用带中心电偶的钢探头在淬冷过程中产生的电势信号和信号处理技术获得了冷却过程的瞬时动态曲线。研究了不同尺寸探头和在不同淬火介质中的动态曲线,并与TTT和CCT曲线作了比较。结果表明,钢在具有物态变化的介质中淬火时,冷却速度剧烈波动主要出现在钢被浸入淬火剂的初始阶段,探头尺寸越小,冷却介质的冷却能力越强,冷却过程越不稳定;此外,冷却三阶段在动态曲线上没有明确的分界。在实际淬火操作中,宜选用特性点较高的淬火剂,以利于工件在动态特性变化大的范围内进行自适应调整。而在过冷奥氏体转变的快冷阶段,宜保持匀速冷却,以减少动态波动的干扰。动态波动程度低而又无物态变化的单一阶段冷却最有利于过程控制和减小工件畸变。     

熔模铸件凝固过程冷却曲线的测量方法

熔模铸件凝固过程冷却曲线对ProCAST模拟参数的反算求解和优化有重要作用。通过对熔模铸钢件凝固过程冷却曲线的测量方法进行研究并确定铸件内部冷却曲线的测量方法,试验测试出了精度较高的铸件冷却曲线。     

Influence of Steel Grade on Surface Cooling Rates and Heat Flux during Quenching

Immersion quenching is one of the most widely used processes for achieving martensitic and bainitic steels. The efficiency and quality of quenching are generally tested using standard quench probes for obtaining the cooling curves. A host of parameters like quenchant type, steel grade, bath agitation, section thickness, etc., affect the cooling curves. Cooling curve analyses covered under ASTM standards cannot be used to assess the performance of a quenchant for different grades of steel, as they use a common material for the probe. This article reports the development of equipment, which, in conjunction with mathematical models, can be used for obtaining cooling curves for a specific steel/quenchant combination. The mathematical models couple nonlinear transient inverse heat transfer with phase transformation, resulting in cooling curves specific to the steel grade-quenchant combination. The austenite decomposition models were based on an approach consistent with both the TTT diagram of the steel and Fe-C equilibrium phase diagrams. The TTT diagrams for the specific chemistry of the specimens and the thermophysical properties of the individual phases as functions of temperature were obtained using JMatPro software. Experiments were conducted in the laboratory for computing surface temperature and heat flux at the mid-section of a 25-mm diameter by 100-mm-long cylindrical specimen of two types of steels in two different quenchants. A low alloy steel (EN19) and a plain carbon steel (C45) were used for bringing out the influence of austenite transformation on surface cooling rates and heat flux. Two types of industrial quenchants (i) a mineral oil, and (ii) an aqueous solution of polymer were used. The results showed that the cooling curves, cooling rate curves, and the surface heat flux depended on the steel grade with the quenchant remaining the same.     

聚合物冷却介质和热处理冷却技术（二）

冷却技术是热处理中的重要和关键问题。聚合物冷却介质的应用和发展与冷却技术紧密相关。概要介绍PVA、PAG、PSA、PVP、PEOX、PEG、PMI和PAM等聚合物冷却介质及它们对冷却机理的影响。最后阐述聚合物冷却介质的维护。     

聚合物冷却介质和热处理冷却技术（一）

冷却技术是热处理中的重要和关键问题。聚合物冷却介质的应用和发展与冷却技术紧密相关。概要介绍PVA、PAG、PSA、PVP、PEOX、PEG、PMI和PAM等聚合物冷却介质及它们对冷却机理的影响。最后阐述聚合物冷却介质的维护。     

Epoxidized Soybean Oil: Evaluation of Oxidative Stabilization and Metal Quenching/Heat Transfer Performance

Vegetable and animal oils as a class of fluids have been used for hundreds of years, if not longer, as quenchants for hardening steel. However, when petroleum oils became available in the late 1800s and early 1900s, the use of these fluids as quenchants, in addition to their use in other industrial oil applications, quickly diminished. This was primarily, but not exclusively, due to their generally very poor thermal-oxidative instability and the difficulty for formulating fluid analogs with varying viscosity properties. Interest in the use of renewable fluids, such as vegetable oils, has increased dramatically in recent years as alternatives to the use of relatively non-biodegradable and toxic petroleum oils. However, the relatively poor thermal-oxidative stability has continued to be a significant reason for their general non-acceptance in the marketplace. Soybean oil (SO) is one of the most highly produced vegetable oils in Brazil. Currently, there are commercially produced epoxidized versions of SO which are available. The objective of this paper is to discuss the potential use of epoxidized SO and its heat transfer properties as a viable alternative to petroleum oils for hardening steel.     

弹簧钢淬火残余应力模拟

对AISI 5160H弹簧钢圆柱试样在不同温度的25％水溶性聚(亚烷基)二醇UCONHT淬火液和Arco521淬火油中淬火产生的残余应力及畸变进行了对比性研究。试棒的直径分φ20．56mm(0．81 inches)和φ13．45mm(0．53 inches)两种。先用INC-PHATRAN代码计算出试样随时间变化的传热系数，并用ABAQUSA际准有限元软件估算热处理过程中的残余应力和畸变。在试样中心放置热电偶，测出冷却曲线，根据所测的冷却曲线，用INC-PHATRAN解决了伴随相变时的逆向热传导问题。试验了这两种淬火介质，力图将热处理畸变和开裂减少到最少,并得出了颇有价值的结论。     

UCON E型淬火介质在大模块工件上的应用

测定和分析了包括UCONE在内的几种冷却介质的冷却速度,讨论了UCONE淬火剂的应用技术问题,如介质浓度、温度以及消耗量和环境因素等。结果表明,UCONE水基淬火剂在低温区的冷却性能接近油,可作为油的代用介质。经多年生产实践,证明浓度为15％的UCONE水基淬火剂可用于模具钢、结构钢等大件的淬火处理,并取得良好的效果。     

滑槽淬火系统的推荐设计

上前聚合淬火剂在各类热处理中的应用日益增加,本文提供了一系列推荐的设计指导原则及一些已成功动用的滑槽淬火装置的示意图例。