钒对Cr12Mo模具钢渗氮层及其摩擦学行为的影响

在Cr12Mo和Cr12MoV模具钢表面进行气体渗氮处理,对比分析了V对Cr12Mo模具钢渗氮层显微结构及其摩擦学行为的影响。结果表明,气体渗氮后两种模具钢的表面均制备出深度约120 μm的渗氮层,由表及里依次为渗氮层、扩散层和基体;V提高了模具钢的耐磨性,Cr12MoV表现出较好的耐磨效果;相比V对模具钢基体和扩散层硬度的提升而言,V对渗氮层最大硬度值附近区域的硬度提升幅度更为明显;V对两种模具钢渗氮层耐磨性的影响并不明显,但V的主要贡献在于促进了渗氮时N的有效渗入,大大提高了渗氮层与扩散层间的界面结合力,避免了渗氮层与扩散层间的开裂,促使磨损机制由疲劳磨损转变为黏着磨损,进一步提高了渗氮层的服役寿命。     

2Cr13钢的表面气体渗氮处理

用光学金相显微镜、扫描电子显微镜、X射线衍射(XRD)仪及显微硬度计对经气体渗氮处理的2Cr13钢试样进行了组织结构分析,并利用销-盘摩擦磨损试验机对渗氮的盘与未渗氮销摩擦副进行摩擦磨损试验.结果表明,520℃×20 h渗氮可使2Cr13马氏体不锈钢的渗氮层深度达到165 μm,处理后试样的显微硬度约为处理前的2.5倍.处理后试样的耐磨性能得到了较大的提高,渗氮盘试样的磨损表面未出现裂纹,而未渗氮销的磨损表面存在严重的裂纹.     

Characterization and tribological properties of composite 3Cr13/FeS layer

The 3Cr13 coating was prepared on the surface of 1045 steel by high velocity arc spraying method, and then treated by low temperature ion sulfuration to obtain the solid lubrication composite 3Cr13/FeS layer. SEM was used to observe the surface, cross-section and worn scar morphologies. XRD was utilized to analyze the phase structure. X-ray stress determinator was utilized to measure its residual stress. The nano-hardness and elastic modulus of composite 3Cr13/FeS layer were surveyed by the nano-indentation tester. The tribological properties were investigated on a ball-on-disk wear tester under dry and oil lubrication conditions. The results showed that the friction coefficient and wear scar depth of the composite 3Cr13/FeS layer were always lower than those of FeS film and 1045 steel under dry and oil lubrication conditions. Therefore the composite 3Cr13/FeS layer had excellent Friction-reduction and anti-wear properties.     

淬火温度对2Cr13不锈钢组织和性能的影响

对2Cr13不锈钢进行水淬火实验,研究了淬火温度对2Cr13不锈钢组织和性能之间的关系.发现在1050℃淬火时,试样的硬度值基本达到了最高,其原因是因为碳化物大多被溶解,铁素体的含量已经非常低.在1050℃淬火时,奥氏体晶粒开始长大,不过晶粒长大的幅度并不是很大,所以2Cr13不锈钢在1050～1070℃淬火对于要求高硬度用钢是比较理想的.     

2Cr13不锈钢的回火脆性

研究2Cr13不锈钢在回火脆性温度区间附近进行回火后,硬度、冲击性能的变化和断口形貌演变。结果表明,2Cr13不锈钢在490~550 ℃回火后,硬度处于40~50 HRC之间,相应的冲击性能呈现下降趋势;在570~620 ℃回火后,不锈钢的硬度在30~38 HRC范围内,冲击性能逐渐升高。通过对冲击断口形貌进行观察,在490~560 ℃回火,不锈钢断裂模式由解理断裂向沿晶断裂转变;随着回火温度升高,最终转变为沿晶+解离的断裂模式,微观上沿晶断裂断面尺寸逐渐缩小,解离数量逐渐增多,表现为宏观上冲击性能的提高。     

20Cr2Ni4A钢和17Cr2Ni2MoVNb钢渗碳层的组织与性能

研究了相同热处理工艺下20Cr2Ni4A和17Cr2Ni2MoVNb钢渗碳层的组织和性能特点。结果表明,17Cr2Ni2MoVNb钢的原材料和热处理后的晶粒比20Cr2Ni4A钢的均匀细小,经淬火+低温回火后,20Cr2Ni4A钢心部晶粒度等级为7级,17Cr2Ni2MoVNb钢心部晶粒度等级为8级。渗碳层晶粒呈梯度变化,最外层最粗但仍与心部晶粒尺寸相当;这得益于V、Nb等微量元素形成的碳化物对晶界的钉扎作用,同时因为含有更多的碳化物颗粒使得17Cr2Ni2MoVNb钢的显微硬度略高于20Cr2Ni4A钢。17Cr2Ni2MoVNb钢的渗层比20Cr2Ni4A钢的具有更高的硬度和更多的碳化物使其耐磨性更优。     

超声波冷锻对Cr12MoV钢渗氮组织与性能的影响

为优化渗氮工艺,提高渗氮层的厚度与硬度,提出用超声波冷锻技术(Ultrasonic cold forging technology,UCFT)对Cr12MoV模具钢进行表面纳米化预处理,并在450℃和520℃两个温度条件下离子渗氮.采用扫描电镜、金相显微镜、白光形貌仪、X射线衍射仪和维氏显微硬度计对样品的微观组织结构和性能进行表征.结果表明:UCFT是一种能与离子渗氮有效复合的预处理工艺,经UCFT表面纳米化预处理后,Cr12MoV模具钢表面形成表面硬度约520 HV,厚度为350 μm的塑性变形影响层;经UCFT表面纳米化预处理后和离子渗氮复合处理后,渗氮层厚度与硬度与原始样品直接渗氮相比有显著提高;UCFT预处理后在520℃离子渗氮4h,材料表面硬度可高达1350 HV,复合改性层厚度也可增至约400 μm.     

Microstructure and vacuum tribological properties of 1Cr18Ni9Ti steel with combined surface treatments

A sulfide film was fabricated on the nanocrystalline layer of 1Cr18Ni9Ti stainless steel by a two-step method of supersonic fine particles bombarding (SFPB) and low temperature ion sulfurization treatments. The microstructure and mechanical properties of the nanocrystallized surface and the sulfide film were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy (equipped with EDS), augur energy spectroscopy, X-ray photoelectron spectroscope, and nano-indenter. The tribological behaviour of the treated (after SFPB and sulfurizing treatments) 1Cr18Ni9Ti steel in vacuum was investigated on a ball-on-disk tribometer. The results showed that, randomly oriented equiaxial nanograins with the mean grain size less than 30 nm were formed in the top surface layer of the SFPB treated sample, and a compact and uniform sulfide film mainly composed of FeS was obtained after the succedent sulfurizing treatment. Compared to the original 1Cr18Ni9Ti steel, the treated surface revealed lower friction coefficient and better wear resistance in vacuum, and the variation of tribological properties with atmospheric pressure of the treated samples was not significant. The dominant wear mechanisms of the treated 1Cr18Ni9Ti in vacuum were abrasive wear and fatigue wear.     

Influence of forming atmosphere on the deposition characteristics of 2Cr13 stainless steel during laser solid forming

A series of single track clads and bulk samples were prepared by laser solid forming under atmospheres of air, argon and nitrogen. The forming atmosphere has little effect on the variation of the width and height of a single track clad with scanning velocity, laser power and feeding rate. Under air, the width and height of single track clads are the largest. Under argon, they are slightly larger than those under nitrogen when the laser energy density is high. For bulk samples prepared under air and nitrogen, both sidewalls of the cross-section tilt inward in the lower part; with an increase in the deposition height, the sidewalls tend to be oriented vertically. Under argon, the sidewalls maintain their severe inward tilts from the bottom to top of the bulk sample. Under air, the bulk sample is covered by oxide dross. Fine and dense metal beads are attached to the lower sidewalls under argon, but these beads are coarse and sparse under nitrogen. The effects of the forming atmosphere on the effective energy, effective mass and deformation of the molten pool during laser solid forming were analyzed. The influence of the atmosphere is attributed to the exothermic oxidation reaction under air, the more extensive plasma plume effect under argon and the larger deformation of the molten pool under air and nitrogen.     

3Cr钢和13Cr钢在高矿化度CO2环境中的腐蚀行为

为了预测油井管钢在高矿化度、含CO2的储层环境中可能发生的腐蚀,为该储层推荐在开发周期内安全经济的材质,采用高温高压反应釜研究了3Cr钢和13Cr钢在模拟储层环境中的腐蚀行为,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量色散X射线能谱(EDS)分析了3Cr钢和13Cr钢的腐蚀产物膜特征.从腐蚀速率、清理腐蚀产物后试样的表观特征、腐蚀产物的表面形貌、横截面腐蚀试样形貌和腐蚀产物化学成分方面探讨了3Cr钢和13Cr钢在CO2环境中的腐蚀特征随温度和含水率的变化规律及反应时间对其的影响.结果表明,3Cr钢在CO2分压为0.2 MPa,Cl-含量139 552mg/L的环境中会发生极严重腐蚀,且试样表面产物膜在微观上分布不均匀,存在局部不完整;13Cr钢发生轻度腐蚀,在所测试样中未观测到点蚀,即3Cr钢不适用于该高矿化度CO2环境而13Cr钢能够满足要求.     

焊后热处理对1Cr18Ni9Ti与2Cr13钢焊接接头组织和性能的影响

通过钨极氩弧焊方法,对1Cr18Ni9Ti与2Cr13钢实施焊接,并对焊接接头整体进行焊后热处理。采用OM、SEM对2Cr13与1Cr18Ni9Ti钢热处理前后的焊接接头组织进行分析,利用显微硬度计、电子万能拉伸机测量了焊接接头的力学性能。结果表明,1Cr18Ni9Ti和2Cr13钢焊接接头热处理前焊缝组织为典型的柱状晶,组织为板条马氏体+残留奥氏体+碳化物;热处理后焊缝组织为回火索氏体,而且碳化物析出量也明显增多。拉伸时,热处理前后焊接接头断裂的部位都发生在奥氏体不锈钢热影响区一侧,热处理前后焊接接头的抗拉强度分别约为635.56、649.44 MPa;焊缝区的显微硬度分别约为276、222 HV0.5,热处理后焊接接头的整体显微硬度比热处理前的明显降低。     

Tribology and cyclic oxidation behavior of plasma nitrided valve steel

In this study, the tribology and cyclic oxidation behavior of plasma nitrided DIN 1.4871 austenitic valve steel were investigated. For this purpose plasma nitriding treatments were carried out in nitrogen and hydrogen with ratio N₂/H₂: 1/3 at 10 Torr pressure. Nitriding cycles of 400, 450, 500 and 550 °C for 7 h were selected. To remove oxide layer and to enhance diffusion, an effective sputter cleaning procedure was applied in argon and hydrogen gases. The pin-on-disc sliding wear experiments were performed at a load of 6 N and sliding velocity of 0.1 m/s in normal atmosphere under dry condition. Cyclic oxidation tests used to evaluate the oxidation characteristics of the samples consisted of 50 cycles each 30 min at 750 °C. The structure and properties of the samples were examined by optical and scanning electron microscopy (SEM), microhardness measurements and X-ray diffraction. The results indicated plasma nitriding at all temperatures increased the wear resistance of valve steel when sliding against bearing steel. The 550 °C nitrided layer, with CrN, Fe₄N and Fe_2-3N on the surface, was most effective in improving wear resistance. In the case of cyclic oxidation, the results showed that oxidation resistance depends strongly on nitriding temperature. Nitriding at 450 °C produced a layer of predominantly “S” phase which was more effective in improving the oxidation resistance of valve steel.     

基于第一性原理掺杂稀土Ce的Cr13钢组织及其抗CO_2腐蚀性能

基于第一性原理计算法,采用CASTEP模块计算稀土Ce掺杂Cr13钢的吸附能,分析稀土Ce对Cr13钢耐CO2腐蚀性能的微观影响机制。通过等离子电弧炉制备添加不同含量Ce元素的Cr13钢,测试合金的显微组织及其在含饱和CO2的3.5%(质量分数)Na Cl液中的腐蚀电化学行为。结果表明:Cr13钢掺杂稀土Ce后,吸附结构的稳定性减小,Ce含量为0.1%(质量分数)时,吸附结构的稳定性最小。适量稀土Ce添加可细化基体铁素体晶粒、减小碳化物的数量及偏聚。稀土Ce掺杂Cr13钢在含饱和CO2介质中呈现出明显的钝化行为,Ce的添加量与钝化稳定性间存在临界值,当稀土Ce添加量为0.1%时,钝化电流密度最小、钝化区间最宽,具有最优的抗CO2腐蚀性能。第一性原理计算方法在预见材料耐CO2腐蚀性能方面具有很强的可靠性,对设计耐蚀材料具有较强的指导意义。     

30Cr2MnSiNi2WMo钢组织研究

研究了不同温度回火后30Cr2MnSiNi2WMo钢的微观组织。结果表明,210 ℃回火后钢的组织为具有高密度位错的板条马氏体及与基体共格的M₂C;510 ℃回火后α相发生明显回复,M₂C长大弥散分布于基体。Cr含量的增加,Mo、W元素的加入,提高了30Cr2MnSiNi2WMo钢的回火抗力。     

热处理对1Cr18Ni9Ti与2Cr13钢板焊接接头耐腐蚀性的影响

通过填丝钨极氩弧焊方法对1Cr18Ni9Ti与2Cr13钢板进行焊接,并对焊接接头进行焊后热处理.采用SEM对焊接接头热处理前后的组织进行观察及分析;采用模拟海水浸泡试验,测量了焊接接头的交流抗阻和极化曲线.结果表明,1Cr18Ni9Ti和2Cr13钢板焊接接头热处理前焊缝为典型的柱状晶,组织为板条马氏体+奥氏体+第二...     

1Cr11Ni2W2MoV钢的离子渗氮

利用脉冲直流辉光等离子技术,对1Cr11Ni2W2MoV马氏体热强不锈钢进行不同工艺参数的离子渗氮。利用光学显微镜、显微硬度计、XRD对渗氮层的显微组织及硬度进行了分析。结果表明,在所选用的离子渗氮工艺参数下,1Cr11Ni2W2MoV钢渗层只由扩散层组成,渗氮温度≤560℃时,渗层主要由固溶N原子的α相组成,并伴有少量的γ'-Fe4N和CrN析出;随着渗氮温度的升高和渗氮时间的延长,固溶N原子的α相逐渐转变成γ'-Fe4N相,当处理温度达到590℃时,渗层主要由γ'-Fe4N和Cr N组成。离子渗氮后渗层的表面硬度较未渗氮前有显著的提高,在一定范围内,渗层的表面硬度和渗层深度都随着渗氮温度和渗氮时间的增加而增加,渗层硬度梯度分布也随着渗氮时间的延长变得平缓。     

ZGMn13Cr2钢水韧处理中的脱碳行为

研究了不同水韧条件下ZGMn13Cr2钢的脱碳行为,分析了实际脱碳深度与理论计算之间的关系,并对传统的计算模型进行了修正.结果表明,水韧处理加热温度越高,保温时间越长,脱碳越严重.当加热温度为1000℃时,实际脱碳深度与理论脱碳深度相似;加热温度为1050℃和1100℃时,由于氧化反应的加剧以及碳化物的作用,实际脱碳深...     

00Cr12Ni9Mo4Cu2Ti马氏体时效不锈钢离子渗氮组织和性能

对00Cr12Ni9Mo4Cu2Ti马氏体时效不锈钢进行了离子渗氮处理,研究了不同渗氮条件下所形成的渗氮层的相结构与性能。结果表明:经离子渗氮后的00Cr12Ni9Mo4Cu2Ti马氏体时效不锈钢的表面硬度、耐磨性都有明显的提高,表面硬度最高达到了1350HV0.05。当样品在400℃渗氮时,表层新相主要由α相组成;当渗氮温度上升至500℃时,表层新相主要由αN相、γ′-Fe4N相、ε相组成,并有大量的CrN相形成;当渗氮温度高于600℃时,ε相、CrN的含量继续增加,γ′-Fe4N相逐渐减少,αN相几乎完全分解。伴随着CrN相的生成,样品的耐磨性得到了提高,表面耐腐蚀性能有一定下降。实验还观察到该马氏体时效不锈钢渗氮层中有微裂纹产生,裂纹的形成与样品的残余内应力和氮化物相生成有关。     

2Cr13钢机械性能的回归分析

本文利用电子计算机,对长期生产中积累的大量2Cr13钢机械性能数据进行了回归分析。建立了性能之间显著性很高(α=0.01)的回归方程。可辅助设计、指导生产。     

回火温度对2Cr13不锈钢应力腐蚀开裂和力学滞后的影响

采用慢应变试验法(SSRT)测试了2Cr13不锈钢在1020℃淬火及不同回火温度条件下的应力腐蚀开裂(SCC)特性,并利用电阻应变计传感器设计原理,测试了回火温度对2Cr13钢力学滞后的影响。结果表明,在270~420℃回火区间,随着回火温度升高,2Cr13钢强度略有增加,滞后略微减小,而应力腐蚀抗力则显著降低。分析认为,在试验温度区间,随温度升高,回火温度接近2Cr13钢敏化和第一类回火脆性温度,加之二次硬化效应,使得该材料应力腐蚀抗力随回火温度升高而显著降低;2Cr13钢力学滞后和其强度及亚结构有关,滞后误差随着材料强度增加而减少。