真空分级淬火对8Cr4Mo4V钢组织和性能的影响

在真空条件下对航空轴承用8Cr4Mo4V钢进行不同温度的分级淬火并采用扫描电镜观察其微观组织、用XRD谱进行相分析并测试洛氏硬度、冲击性能和旋转弯曲疲劳性能,研究了真空分级淬火对其微观组织和力学性能的影响。结果表明,真空分级淬火后的8Cr4Mo4V钢其微观组织由下贝氏体、马氏体/残余奥氏体和碳化物组成;随着分级淬火温度的提高,淬火和回火态钢中析出碳化物的数量增加,残余奥氏体的含量降低。分级淬火温度为580℃时淬火态钢中贝氏体的含量最高(达到13.87%),残余奥氏体的含量为28.59%。回火后析出碳化物的含量和洛氏硬度均为所有分级温度中的最大值,分别为4.37%和62.38HRC。真空分级淬火能提高8Cr4Mo4V钢的综合力学性能。与未分级真空淬火相比,进行580℃×10 min真空分级淬火的8Cr4Mo4V钢的冲击韧性提高了23.3%,旋转弯曲疲劳极限提高了110 MPa。     

固溶处理对 0Cr17Ni4Cu4Nb钢耐腐蚀性能及组织的影响

运用极化曲线、循环极化曲线等电化学方法研究了0Cr17Ni4Cu4Nb钢经不同工艺固溶处理后的耐海水腐蚀性能,并对显微组织进行了观察和分析。试验结果表明:在1040℃下该不锈钢经60min固溶处理可获最佳的耐海水腐蚀性能和较高的硬度值。其显微组织主要为淬火马氏体+少量的残余奥氏体+δ-铁素体,且晶粒大小均匀。     

Surface treatment of DZ4 directionally solidified nickel-based superalloy by high current pulsed electron beam

Surface treatment of DZ4 directionally solidified nickel-based superalloy was carried out by using high current pulsed electron beam (HCPEB) technique. Microstructure changes in modified surface layer were characterized together with their corrosion property. It is found that the treated surface becomes rougher with increasing the number of HCPEB pulse due to the formation of craters occurring preferentially in the interdendritic areas. The thickness of remelted layer increased slightly when more HCPEB pulses applied and reached about 3 μm after 10 HCPEB pulses. The corrosion resistance of modified surfaces exhibited an effective improvement when measured in 0.5 mol/L sulfuric acid solution. The factors that influence the corrosion resistance of DZ4 alloy were discussed by considering the surface purification effect featured by HCPEB surface treatment.     

Effects of copper content on the machinability and corrosion resistance of martensitic stainless steel

The effects of copper addition on the machinability and corrosion resistance of martensitic stainless steel 4Cr16Mo are presented in the article. The results showed that the machinability of stainless steel 4Cr16Mo was obviously improved by adding Cu. When the content of copper in the stainless steel was 1.4%, the machinability of stainless steel was optimal. With the increase in the content of copper, the corrosion resistance of stainless steel 4Cr16Mo was improved. From the observation of the electron backscattered diffraction (EBSD) and high resolution electron microscopy (HREM), it can be seen that Cu-rich phases were dispersed in the stainless steel, and determined to be about 10 nm.     

Mechanisms of hardening, wear and corrosion improvement of 316 L stainless steel by low energy high current pulsed electron beam surface treatment

The mechanisms of corrosion and wear improvements by low energy high current pulsed electron beam (LEHCPEB) have been investigated for an AISI 316 L steel. Selective purification followed by epitaxial growth occurred in the top surface melted layer (2-3 μm thick) that was softened by tensile stresses and, to a much lower extent, by lower efficiency of MnS precipitation hardening. Electrochemical impedance spectroscopy and potentiodynamic polarization analyses used to model the corrosion behavior revealed that, while craters initiated at MnS inclusions initially served as pitting sites, the resistance was increased by 3 orders of magnitude after sufficient number of pulses by the formation of a homogeneous covering layer. The wear resistance was effectively improved by sub-surface (over 100 μm) work hardening associated with the combine effect of the quasi-static thermal stress and the thermal stress waves. The overall results demonstrate the potential of the LEHCPEB technique for improving concomitantly the corrosion and wear performances of metallic materials.     

45 钢表面激光相变硬化改性组织及耐蚀性能

目的为了改善45钢表面状态,提高其表面性能,采用CO2激光器对其表面进行激光相变硬化处理。方法利用带有能谱的扫描电子显微镜(SEM/EDS)、盐雾试验机等,对激光相变硬化层组织及耐蚀性能进行了观察和分析。结果激光相变硬化层由熔化区、相变硬化区和热影响区三部分组成,其组织依次为:混合马氏体+未溶碳化物、针状马氏体、残余奥氏体。随扫描速度增加,耐蚀性先变好而后变差。结论激光相变硬化处理可改善45钢的表面性能,显著提高其耐蚀性能。     

Konzept zur Verbesserung der Meerwasserbeständigkeit von Wälzlagerstahl

To develop corrosion‐resistant hardenable bearing steels for seawater applications the contents of Mo and Cr were raised in respect to X65Cr14 and the carbon content was lowered by making use of the soluble N content. The steels X51CrN(14)14 and X51CrMoN(14)15‐3, to be molten under normal pressure, and steel X33CrMoN(32)15‐3, to be processed under an N₂ pressure of = 4.7 bar, promise a higher resistance to pitting corrosion and a lower liability of coarse eutectic carbides in segregated areas without discernible disadvantages in respect to hardness and retained austenite. The study has led to a pre‐selection of promising new steels just by thermodynamic calculations and empirical equations without time‐consuming and costly experiments.     

铸造双相不锈钢点腐蚀行为研究

采用化学浸泡腐蚀试验及微观组织和化学成分分析研究了5种铸造双相不锈钢在6%Fe Cl3溶液中的点腐蚀行为,并与316L奥氏体不锈钢进行了对比。结果表明,铸造双相不锈钢的抗点腐蚀性能均优于316L的,腐蚀速率和点腐蚀深度均小于316L奥氏体不锈钢的;双相不锈钢主要耐点蚀能力合金元素在奥氏体和铁素体相内分布不均匀,铬、钼更多地分配于铁素体相内,而镍、氮则更多地分配于奥氏体相内,铁素体相的耐点蚀指数PRE(Cr%+3.3Mo%+16N%)大于奥氏体相;双相不锈钢的耐点腐蚀性能与化学成分有关,随着PRE的增加,双相不锈钢的耐点腐蚀性能提高,铜元素在铁素体内析出的富铜相导致点蚀优先在铁素体内发生和发展。     

高速钢高温变形再结晶规律研究

本文研究了W9Mo~3Cr~4V钢的热变形奥氏体动态再结晶规律。结果表明:由于形变诱发析出碳化物的影响,W9Mo~3Cr~4V钢热变形奥氏体动态再结晶方式与低碳低合金钢的晶界弓出机构和晶界生核机构不同,是通过亚晶合并形成再结晶晶粒的,即亚晶合并机构。当形变速率较低时,可由亚晶粒直接形成再结晶晶粒。形变温度和形变速率对W9Mo~3Cr~4V钢热变形奥氏体动态再结晶影响比较复杂,不能简单地用Z参数来统一描述。     

Corrosion resistance of multilayer coatings of nanolayered Cr/Ni electrodeposited from Cr(III)-Ni(II) bath

In this study the corrosion resistance of chromium and nickel single layers and multilayer coatings of nanolayered Cr/Ni, electrodeposited from Cr(III)-Ni(II) baths on low carbon steel substrates, has been studied. The coatings were electrodeposited from a bath using pulse current and modulated agitation. The total thickness of single layer and multilayer coatings was fixed at 5 μm and multilayer coatings with different modulation wavelengths and Cr to Ni thickness ratio were electrodeposited. Corrosion behavior of coatings was then studied by using potentiodynamic polarization test and electrochemical impedance spectroscopy in 0.1 M H₂SO₄. The results showed that Cr and Ni single layers had low corrosion resistance due to the presence of surface cracks and pores, respectively. On the other hand, optimized 20 nm Cr/50 nm Ni multilayer deposition significantly improved corrosion resistance.     

Electrochemical corrosion behavior of carbon-based thin films in chloride ions containing electrolytes

Commercially available carbon-based thin films consisting of single layers of amorphous diamond-like carbon or multilayers of crystalline TiAlN or CrN with diamond-like carbon top coatings were evaluated in relation to their electrochemical corrosion behavior in chloride ions containing electrolytes. The hardened working steel (an alloy of 0.9% C, 4.1% Cr, 4.9% Mo, 1.8% V, 6.4% W) was used as a substrate material.The potentiodynamic corrosion behavior of coated samples was tested in 3.5 wt.% NaCl solution and Hank's balanced body solution, HBBS (0.89 wt.% NaCl, further chlorides, sulfates, carbonates and phosphates). The multi-layers TiAlN + a-C:H:W and CrN + a-C:H:W exhibited only a minor improvement in corrosion resistance. Single layers of amorphous diamond-like carbon coating without hydrogen (a-C) spall off during the corrosion tests in chloride containing media. A minor improvement of the corrosion resistance is possible. The a-C:H and the a-C:H:Si, which contain hydrogen, showed the best corrosion resistance with a 100 times lower corrosion current density.     

1Cr12Ni2W1Mo1V不锈钢表面等离子堆焊司太立熔覆层的组织及性能

为提高1Cr12Ni2W1Mo1V不锈钢的耐水蚀性能,采用等离子堆焊方法在其表面制备司太立熔覆层。研究了涂层的显微组织和显微硬度分布,分析了涂层的抗微粒冲蚀性能和耐水蚀性能。结果表明:司太立熔覆层与基体材料冶金结合良好,熔覆层组织细小、分布均匀,基体为枝晶状Co-Cr固溶体,枝晶间较均匀地分布着黑色碳化物,主要为M7C3和少量WC颗粒;司太立熔覆层的平均显微硬度(382.38 HV4.9 N)约为基材平均硬度(195.29HV4.9 N)的1.96倍,最高硬度值达到了421.00 HV4.9 N;堆焊第2层的硬度明显高于第1层的;司太立熔覆层合金的抗微粒冲蚀性能优于基材,其水蚀速度比基材小,在基材1Cr12Ni2W1Mo1V上堆焊司太立合金能有效提高其耐水蚀性能。     

Corrosion-resistant analogue of Hadfield steel

The concept of alloying austenitic steels with carbon + nitrogen is used for the development of a corrosion-resistant austenitic CrMn steel having an impact wear resistance close to that of the Hadfield steel. A higher stabilization of the austenitic phase by C + N, as compared to carbon or nitrogen alone, is substantiated by ab initio calculation of the electron structure, measurements of the concentration of free electrons and calculations of the phase equilibrium. Based on these results, the compositions (mass%) Cr18Mn18C0.34N0.61 and Cr18Mn18C0.49N0.58 were melted and tested along with Hadfield steel Mn12C1.2. Mechanical tests have shown that, as compared to the Hadfield steel, the experimental steels possess a higher strength, plasticity, hardness and the same resistance to impact wear. TEM studies of the surface layer after impact treatment revealed a mixture of the amorphous phase, nanocrystals and fine-twinned austenite. At the same time, using Mössbauer spectroscopy of conversion electrons, the ferromagnetic ordering was found in the surface layer of up to 10 μm in depth, which is the sign of the strain-induced martensitic phase. The hypothesis of a transition from the low-spin to the high-spin state of the iron atoms within the thin twins in austenite was proposed in order to interpret the discrepancy between TEM and Mössbauer studies. Potentiodynamic measurements and immersion tests show that the CrMnCN steels possess a significantly higher pitting potential and resistance to general corrosion in comparison with Hadfield steel.     

Study on the Tribological Properties and Composition of W6Mo5Cr4V2 High Speed Steel Implanted by Boron

Boron atoms were implanted into W6Mo5Cr4V2 high-speed steel (HSS) in CC-60 ion implantation machine to improve its tribological properties. The influence of boron implantation dose on the microhardness, friction coefficient and wear resistance of HSS were investigated. The experiment results showed that the implantation of boron can improve the tribological properties of W6Mo5Cr4V2 steel greatly. Then the phase and composition of implanted layer were analyzed by XRD and XPS. The analysisresult revealed that the interface between the implantation layer and substrate appeared to be mixed.With the increase of boron dose, the compound of δ-WB, CrB, BFe3 are the main additive phases, which supposed to be the main reason to improve the tribological properties of W6Mo5Cr4V2 steel.     

Distinct beneficial effect of Sn on the corrosion resistance of Cr-Mo low alloy steel

In this work,the beneficial effect of Sn addition on the corrosion resistance mechanism of Cr-Mo low alloy steel was studied.Results demonstrated that Sn improves the corrosion resistance of the steel matrix mainly by influencing the microstructural transformation.Sn addition and the synergistic effect of Sn,Cr,and Mo promote the formation of α-FeOOH,SnO2,SnO,Cr(OH)3,and molybdates,lead to the improved protection and stability of the rust layer.This synergistic effect also endows the inner rust layer with cation selectivity,preventing the further penetration of Cl-and inhibiting the localized corrosion of steel.     

10Cr4Ni4Mo4V钢和Cr4Mo4V钢的特性与断裂行为

对１０Ｃｒ４Ｎｉ４Ｍｏ４Ｖ钢和Ｃｒ４Ｍｏ４Ｖ钢的特性与断裂行为进行了试验研究。结果表明,１０Ｃｒ４Ｎｉ４Ｍｏ４Ｖ钢经微氮渗碳热处理后,其表面硬度、残余应力、断裂韧性及裂纹扩展速率均优于Ｃｒ４Ｍｏ４Ｖ钢的。     

0Cr13Ni5Mo不锈钢电火花强化表面耐腐蚀性能研究

针对我国水轮机过流部件长时间运行后表面腐蚀严重这一问题,选用YG8电极材料对水轮机叶片用0Cr13Ni5Mo不锈钢进行电火花表面强化处理,基于电化学测试技术和交流阻抗测试方法,对强化层的电化学腐蚀性能进行了深入研究.结果表明,强化过程中电极材料与基体材料元素相互熔渗和扩散,强化层内有新的相结构生成,且强化层为冶金结合.与基体材料相比,在腐蚀溶液中电火花强化后试件的自腐蚀电位增大,自腐蚀电流密度减小,试件腐蚀速度变慢,耐腐蚀性能明显提高.     

Effect of alloy elements on the anticorrosion properties of low alloy steel

Effect of alloy elements on corrosion of low alloy steel was studied under simulated offshore conditions. The results showed that the elements Cu, P, Mo, W, V had evident effect on corrosion resistance in the atmosphere zone; Cu, P, V, Mo in the splash zone and Cr, Al, Mo in the submerged zone.     

Dry sliding wear behavior and corrosion resistance of NiCrBSi coating deposited by activated combustion-high velocity air fuel spray process

NiCrBSi is a Ni-based superalloy widely used to obtain high wear and corrosion resistant coatings. This Ni-based alloy coating has been deposited onto 0Cr13Ni5Mo stainless steel using the AC-HVAF technique. The structure and morphologies of the Ni-based coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The wear resistance and corrosion resistance were studied. The tribological behaviors were evaluated using a HT-600 wear test rig. The wear resistance of the Ni-based coating was shown to be higher than that of the 0Cr13Ni5Mo stainless steel because Fe₃B, with high hardness, was distributed in the coating so the dispersion strengthening in the Ni-based coating was obvious and this increased the wear resistance of the Ni-based coating in a dry sliding wear test. Under the same conditions, the worn volume of 0Cr13Ni5Mo stainless steel was 4.1 times greater than that of the Ni-based coating. The wear mechanism is mainly fatigue wear. A series of the electrochemical tests was carried out in a 3.5 wt.% NaCl solution in order to examine the corrosion behavior. The mechanisms for corrosion resistance are discussed.     

双相不锈钢00Cr25Ni7Mo4N敏化过程中的脆化机理研究

研究了双相不锈钢00Cr25Ni7Mo4N在晶间腐蚀试验中发生的脆断现象,采用金相法、扫描电镜和透射电镜对材料的脆断机理进行了分析。研究发现双相不锈钢00Cr25Ni7Mo4N在敏化时有R相、Fe3Cr3Mo2Si2相等脆性相析出,导致材料脆化,冲击韧性下降。最后,给出了双相不锈钢00Cr25Ni7Mo4N热加工后的使用要求。