高铁用结构钢淬透性及热处理工艺试验

对高铁用35CrMo钢、40CrNiMo钢和34CrNiMo6钢淬透性、淬硬性及热处理工艺进行了试验研究。试验结果表明,三种材料中34CrNiMo6钢的淬透性最好;40CrNiMo钢淬硬性较好,但淬硬层深度较浅;35CrMo钢的淬硬性低于40CrNiMo钢,淬透性低于34CrNiMo6钢。三种钢的抗拉强度、屈服强度和硬度均随回火温度的提高而下降,而断后伸长率、冲击韧度则随回火温度的升高而上升。     

高铁车轴用结构钢的热处理和力学性能

研究了高铁车轴用35CrMo3、4CrNiMo6和40CrNiMo钢的淬透性、热处理工艺和力学性能。结果表明,34CrNiMo6钢的淬透性优于其余两种钢;三种钢的抗拉强度、屈服强度和硬度均随回火温度的升高而下降,而断后伸长率、冲击韧度随回火温度的升高而上升。     

推土机齿轮弯曲疲劳试验机夹具的设计及热处理

齿轮是常用的机械传动件,被广泛应用于推土机等多种工程机械。弯曲疲劳是齿轮的主要失效形式,严重影响推土机的使用寿命。为了对一种模数为8的推土机齿轮进行弯曲疲劳试验,设计了弯曲疲劳试验积的夹具,包括压头和支撑架。压头和支撑架分别采用5CrNiMo和35CrMo钢制作,并进行了适当的热处理。对推土机的20CrMnTi、20CrMnMo、22CrNi2MoNb钢渗碳齿轮和42CrMo钢离子渗氮齿轮进行了弯曲疲劳试验。结果表明,压头和支撑架的使用效果良好,达到了设计要求。     

Al对42CrMo螺栓钢淬透性的影响

在42CrMo钢的基础成分上增加Al、Ti元素,通过末端淬火试验和截面硬度试验对比分析Al对42CrMo钢淬透性的影响差异,通过常规力学性能检测对比其与42CrMo钢的力学性能差异。结果表明Al、Ti元素添加可进一步提高淬透性,并且使钢的强度达到1200 MPa级,－40 ℃下KV₂≥27 J,满足低温环境下螺栓用钢的使用要求。采用化学相分析方法,对钢中析出相进行了定性、定量分析,结果表明Ti在钢中添加发挥明显固氮作用,提高了Al元素的固溶量,利用热膨胀法对比测定试验钢的等温转变曲线,证明了增加Al含量,降低了奥氏体临界转变温度,使C曲线右移,明显改善了钢的淬透性。     

基于ELM的齿轮钢淬透性预测模型

利用极限学习机(ELM)研究了20Cr齿轮钢端淬硬度曲线和化学成分的预测,并将其预测结果与传统预测模型进行比较。结果表明,ELM可以根据齿轮钢的化学成分预测其淬透性,计算精度明显优于传统线性拟合及神经网络模型,同时ELM也能通过齿轮钢淬透性硬度曲线反测化学成分,元素含量误差在5%以内。     

高铁齿轮用钢18CrNiMo7-6的端淬曲线与模拟计算

采用3种端淬曲线预测模型计算两炉次高铁齿轮用钢18CrNiMo7-6的端淬曲线,对比端淬硬度检测结果,分析了不同模型的预测误差。结果表明,金满模型的预测结果与端淬试验检测结果误差较小,可以用做这类钢的端淬结果预测。根据端淬曲线预测与实测结果的对比分析,结合相关高铁齿轮用钢技术条件的硬度规范对高铁齿轮用钢18CrNiMo7-6的冶炼成分控制给出了建议。     

轴类材料淬透性与心部硬度关系的研究

本文通过测定17CrNiMo6和20CrMnTiH3轴类材料的淬透性以及不同直径棒料渗碳淬火后的硬度,比较了两种材料心部硬度的差异,并分析了同种材料在不同位置端淬值与心部硬度之间的对应关系。分析认为,不同直径棒料的心部硬度与淬透性曲线上对应的位置是较一致的,与材料的种类关系不大。     

27CrMo钢的奥氏体连续冷却转变

利用热膨胀仪测定了27CrMo钢不同冷却速度下的膨胀曲线,并采用切线法确定了各冷速下的相变温度,结合显微组织绘制出试验钢的CCT曲线,并在全自动热处理线上进行了钢管的淬透性试验。结果表明:1℃/s时,开始发生贝氏体(B)转变;2℃/s时,开始发生马氏体(M)转变;冷速≥30℃/s时,组织主要为板条马氏体。说明27CrMo钢具有较高的淬透性,可用于生产厚壁石油套管。     

新型高合金齿轮渗碳钢17CrNiMo6的热处理

研究高合金齿轮钢17CrNiMo6的热处理工艺特性,对17CrNiMo6钢在不同的渗碳工艺和不同的淬火条件进行处理,对渗碳层的显微组织、渗层淬透性、有效硬化层深度及畸变趋势进行探讨.结果表明,17CrNiMo6钢渗碳件表面含碳量控制在0.7wt%~0.9wt%为宜,若考虑渗层的淬透性,则含碳量控制在0.76wt%左右;采用热油并搅拌的淬火均匀性最佳.     

5Cr2NiMoVSi 钢

正5Cr2NiMoVSi钢是在5CrNiMo钢和4Cr5MoSiV(H11)钢的基础上研制的新钢种。强度高于5CrNiMo钢,稍低于4Cr5MoSiV(H11)钢;冲击韧度高于5CrNiMo钢和4Cr5MoSiv(H11)钢;淬透性接近5CrNiMo钢。加热时奥氏体晶粒长大倾向小,热处理温度范围较宽,可在960~1010℃范围内选择,有利于大尺寸模块长时间加热保温。特别是钢的热稳定性高于5CrNiMo钢,接近于4Cr5MoSiV(H11)钢。因此特别适合与锻件接触时间较长的模具工作面温升较高的压力机锻模,和模锻锤锻模。     

齿轮的渗碳和淬火

简述了渗碳淬火齿轮的常见缺陷及其预防措施,齿轮渗碳前的预备热处理,20CrMo、20CrMnMo、20CrNi2Mo、20Cr2Ni4和18Cr2Ni4W等齿轮用钢渗碳气氛的碳势控制和渗碳后淬火温度的选定等。     

PAG淬火介质在齿轮渗碳淬火中的应用

本文通过对20CrMnMo和20CrNiMo齿轮和齿轴渗碳后采用新型淬火介质淬火,获得了很好的回火组织和力学性能。与普通的淬火油淬火相比,采用14%~16%浓度的PAG淬火处理后齿轮和齿轴的强度、冲击韧性均有很大程度提高,金相组织更均匀,淬透性也有较大幅度提高。     

Kurzzeituntersuchungen zur Auswahl von rostbeständigen Cr-Stählen mit verbessertem Widerstand gegen Schwingungsrißkorrosion

Short-time investigations into the selection of stainless chromium steels with improved corrosion fatigue resistance Using the steel X 20 Cr 13 various short-time test methods have been tested for evaluating the corrosion fatigue susceptibility in concentrated air-saturated sodium chloride solution. In addition the steels X 15 CrNi17, X 35 CrMo 17, X 5 CrNiMoCuNb 14 5, X 4 CrNiCuNb 16 4, X 2 CrNiMoN 22 5 3, X 5 CrNiMoCu 25 5, X 8 CrNiMo 27 5 and X 1 CrNiMoNb 28 4 2 have been studied at room temperature of 80° C using crack propagation, constant straining and pitting corrosion methods. The two last mentioned steels are superiour under the test conditions.     

Heat Treatment Properties of 42CrMo Steel for Bearing Ring of Varisized Shield Tunneling Machine

The heat treatment properties of 42 CrMo steel for bearing ring of varisized shield tunneling machine were investigated by optical microscope(OM), scanning electron microscope(SEM), transmission electron microscope(TEM),and impact tests. The addition of 0.03 wt% C into 42 CrMo steel can increase the hardness. But it reduces the impact energy by 46 J because of the appearance of coarser carbides in the matrix and the carbides along the austenite grain boundary.The addition of 0.40 wt% Mn into 42 CrMo steel can improve hardenability. However, the toughness of steel is also reduced by 26 J mainly because of the coarsening of carbides and the strengthening of matrix. Both hardenability and toughness of 42 CrMo steel can be improved by adding 1.49 wt% Ni and reducing 0.32 wt% Cr. The depth of hardening layer can be raised to 45 mm, and the impact energy at-20 °C is 120 J. Thus, it is concluded that a good combination of hardness, hardenability, and toughness of 42 CrMo steel can be achieved by alloying with adding some content of C and Ni.Detailed content of C and Ni should be on the requirements of heat treatment properties of steel for bearing ring of varisized shield tunneling machine.     

The Effect of Hardenability Variation on Phase Transformation of Spiral Bevel Gear in Quenching Process

The hardenability of gear steel is dependent on the composition of alloying elements and is one of important criteria to assess process of phase transformation. The variation of hardenability has to be considered in control of the microstructures and distortion during gear quenching. In this paper, the quantitative effect of hardenability has been investigated on phase transformations of spiral bevel gears in die quenching. The hardenability deviation of 22CrMoH steel was assessed by using Jominy test. The dilatometry experiments were conducted to build phase transformation kinetic models for steels with low and high hardenability, respectively. The complete die quenching process of spiral bevel gear was modeled to reveal the significant difference on microstructures and temperature history with variation of hardenability. The final microstructures of the gear are martensite in surface layer after quenching process. There are bainite inside the gear tooth and the mixture of bainite and ferrite inside gear for the gear with low hardenability. The microstructure is bainite inside the gear with high hardenability.     

Vergleichende Untersuchungen des SwRK-Verhaltens verschiedener Dampfturbinenschaufelstähle

Comparative investigations into the corrosion fatigue behaviour of different steam-turbine-blade steels Corrosion fatigue tests in NaCl-solution in the temperature range from ambient temperature to 150°C revealed a decrease of the corrosion fatigue strength of the steels X20Cr13 with 1% resp. 2.5% Mo, X4CrNiMo 16 5 1 and X2CrNiMoN 22 5 with increasing temperature; a minimum of the corrosion fatigue strength is reached at 150°C. At temperatures of about 80°C it was found an optimum corrosion fatigue behaviour of the Mo-alloyed steel X20CrMo13 2.5 in comparison with the other investigated steels. It was observed that crack initiation of the ferritic, Mo-alloyed steel is caused by Cl-induced pitting, of the soft martensitic steel by oxide inclusions and of the duplex steel by non metallic, brittle inclusions and/or by grain boundarys of the ferritic/austenitic microstructure. Crack initiation caused by pre-deformation at slip bands was observed on the duplex steel. All materials investigated failed at elevated temperatures. At temperatures higher than 80°C an optimum corrosion fatigue behaviour was not found.     

Schwingungsrißkorrosionsuntersuchungen an ferritischen rostfreien Stählen

Investigation into corrosion fatigue of ferritic stainless steels The corrosion fatigue behaviour has been studied under cyclic flexural load in air and in concentrated NaCl solutions. The materials of construction used in the rest were the steels X 20 Cr 13 and X 20 CrMo 13, and the recently developed steels Inconel X 744 and PV 520 B which are used for turbine blades. The results show that the two last mentioned steels containing, in addition to 26 and 13% Cr respectively, 6 to 7% Ni are characterized by much higher corrosion fatigue resistance (10⁷ cycles). In view of the differences found in the results with respect to the ratio between unnotched and notched specimens, on the one hand in the group X 20 Cr 13 and X 20 CrMo 13, on the other hand in the group Inconel X 744 and PV 520 B the necessity becomes evident of using for corrosion fatigue tests notched specimens too. Nitrided surface layers may exert a considerable influence in the case of short test durations, particularly in the case of the steel X 20 CrMo 13. At test durations exceeding some 100 hours, however, the protective effect of the nitrided layers disappears.