奥氏体不锈钢的氮化

作者观察了气体氮化、盐浴碳氮共渗和离子氮化(氮化后不氧化处理及氮化后氧化处理)对AISI 304、316和321奥氏体不锈钢的腐蚀抗力及磨损性能的影响。表明:氮化处理可明显地降低奥氏体不锈钢的腐蚀抗力,但提高它的磨损抗力。对所有钢种,高温氮化处理后,在盐、醋酸中的腐蚀速率都相近。460℃离子氮化后经氧化处理并不能明显改善奥氏体不锈钢的腐蚀抗力,但可提高磨损抗力和降低磨损速率。     

不锈钢的钝化膜对渗氮的影响及其消除措施

本文主要叙述了Cr13型不锈钢表面钝化膜对气体渗氮渗层不均匀的影响及采用以氮气作载体的电解催渗氮化,可消除钝化膜,加速氮化,使渗层均匀。     

提高奥氏体不锈钢磨损和腐蚀抗力的氮化

氮化在制造工业的各个部门得到了广泛的应用，以期改善奥氏体不锈钢表面的擦伤性能，可是，氮化虽提高其耐磨性，但耐蚀性却下降。自八十年代中期以来，不锈钢的氮化有了重大进展。现在，可以获得同时改善耐磨和耐蚀的氮化层。本文重点介绍该领域的最新进展，并讨论气体和离子氮化层的组织和性能。通过控制工艺参数，可获得各种氮化层组织，低温氮化可获得硬度超过1400HV的单相氮化层，并显著改善其耐腐蚀性能。     

提高奥氏体不锈钢磨损和腐蚀抗力的氮化

氮化在制造工业的各个部门得到了广泛的应用，以期改善奥氏体不锈钢表面的擦伤性能，可是，氮化虽提高其耐磨性，但耐蚀性却下降。自八十年代中期以来，不锈钢的氮化有了重大进展。现在，可以获得同时改善耐磨和耐蚀的氮化层。本文重点介绍该领域的最新进展，并讨论气体和离子氮化层的组织和性能。通过控制工艺参数，可获得各种氮化层组织，低温氮化可获得硬度超过1400HV的单相氮化层，并显著改善其耐腐蚀性能。     

用石墨粉加水玻璃涂氮化箱

气体氮化箱大都是用1Cr18Ni9Ti不锈钢焊接而成。实践证明,用这种材料制造的氮化箱成本高、耐用度低,而且用5～8炉次后,氨的分解率和氨的消耗量就会大大提高。东方机械厂研究使用石墨粉加水玻璃涂氮化箱取得     

关于气体氮化的几个工艺操作问题

普通气体氮化是机床制造、柴油机制造等领域中广泛应用的表面强化工艺。但如所周知,普通气体氮化也存在着一些明显不足之处,如周期长、操作较烦、氮化质量不易稳定、尤其是38CrMoAl钢的氮化层比较脆等。为改进这些缺点,采用离子氮化、各种催渗氮化及气体软氮化等新工艺新技术固然在某些方面有一定成效;但就气体氮化本身来说,其工艺操作也是一个不容忽视的问     

马氏体不锈钢活塞环的气体氮化

对6Cr13Mo马氏体不锈钢活塞环进行了加入NH4Cl的洁净气体氮化处理试验，对产品进行了金相与硬度检测及装车试验。结果表明，由于NH4Cl的活化与催渗作用，经520℃x8h氮化，氮化层深可达0．20mm，最高硬度达到1200HV，且大于800HV的有效层深达0．12mm以上，完全能够满足活塞环的使用要求，其使用寿命与镀铬环相当。该处理工艺可以代替传统的有污染的镀铬工艺。     

1Cr11MoNiWVNbN不锈钢氮化组织异常原因分析及解决措施

对1Cr11MoNiWVNbN不锈钢在600℃气体氮化过程中出现的黑色条纹进行了深入研究。结果表明:黑色条纹不是裂纹,而是一种异常组织。分析这种异常组织出现的原因是和γ'相的存在、碳原子远程迁移、硬度落差、腐蚀剂作用下的电化学作用、冷却介质等有密切联系;提出在625℃氮化、640℃退氮、在氮气保护气氛中冷却的气体氮化方法,获得了层深0.36~0.39mm,硬度798HV,脆性1级,无黑色条纹的渗层。并从理论上解释了这种氮化方法不产生黑色条纹的原因。     

氮化和喷涂MoS2涂层的不锈钢试样振动后抗咬死性能分析

目的 研究氮化和喷涂MoS2涂层的异种不锈钢试样,经振动试验后的抗咬死性能及失效原因.方法 利用三角级数法转化得到了振动参数,对底座(Ⅰ型不锈钢)和拉杆(Ⅱ型不锈钢)的模拟件进行了气体氮化和常温喷涂MoS2涂层处理,采用三维显微镜、XRD、SEM、EDS和模拟振动试验平台对试样进行了表征.结果 Ⅰ型和Ⅱ型不锈钢氮化后的表面物相主要是γ′-Fe4N、ε-Fe2-3N和CrN.Ⅰ型不锈钢和Ⅱ型不锈钢表面的MoS2涂层厚度分别为30～40μm、20～30μm,氮化层的总厚度分别约为165、230μm.在模拟振动平台上,底座与拉杆咬死失效时间在30～45 min之间.底座和拉杆的上、下接触面磨损较严重,内接触面发生了轻微磨损.拉杆的下接触面发生旋转,上接触面继续保持接触,上下接触面的摩擦力大于拉杆的重力,从而发生了咬死现象.结论 底座和拉杆局部表面粗糙度增加、拉杆直径比底座内表面高度方向尺寸大0.28 mm、互溶性大且含立方晶体结构氮化物的氮化层之间直接接触,是振动45 min并旋转后试样发生咬死的主要原因.建议改进底座和拉杆的尺寸、表面处理层和工艺参数.     

辉光离子氮化对马氏体不锈钢性能的影响

对1Crl3马氏体不锈钢进行了辉光离子氮化处理试验，并对氮化试样的金相和硬度进行了分析测定。结果表明520℃辉光离子氮化8h，使1Crl3马氏体不锈钢的氮化层浓度达到0.25mm，最高硬度达到HV732，约为基体硬度的4倍。     

马氏体不锈钢不同渗氮方法对比试验

采用离子渗氮、液体渗氮及气体渗氮对耐蚀耐热马氏体型热稳定不锈钢1Cr12Ni2WMoVNb进行表面改性,研究了不同渗氮方法下不锈钢的硬度、组织形貌、物相变化及脆性,并对3种渗氮方法下不锈钢的耐蚀性及耐高温磨损性能进行了比较。结果表明:3种渗氮方法均可大幅度提高不锈钢的表面硬度,且不同渗氮处理后不锈钢的渗层组织结构大致相同,但表面物相有所差异,离子渗氮后的表面物相主要为Fe₄N及少量CrN相,液体渗氮后为Fe₃O₄及ε相,气体渗氮后为Fe₃O₄、Fe₄N及少量ε相;3种渗氮方法均可提高不锈钢的耐磨损性能,特别是在500~600 ℃下的高温耐磨性得到了大幅提升,但不锈钢渗氮后的耐蚀性均有所降低。     

Influence of initial heat treatment of 17-4 PH stainless steel on gas nitriding kinetics

Results of the investigation of nitrided layers on 17-4 PH type precipitation hardening stainless steel are presented in this paper. The layers have been produced in the process of gas nitriding in a partly dissociated ammonia at temperatures between 410 and 570 °C. Hydrogen chloride admixture to active atmosphere was used as a surface activator. Structure of the nitrided layers were examined using scanning and transmission electron microscopy, X-ray microanalysis (EDX and WDX), and X-ray diffraction. The influence of the initial steel heat treatment on the nitriding kinetics has been considered. 17-4 PH stainless steel was nitrided at various heat treatment conditions, i.e. after solution treatment or ageing at different temperatures. The influence of precipitation processes taking place during the heat treatment before nitriding on the diffusive process kinetics was proven. It was found that, that increasing of steel ageing temperature up to 600 °C before nitriding effects on an increasing of the nitriding kinetics.     

Low-Temperature Salt Bath Nitriding of Steels

Nitriding technology has gone a long way, from the old gas nitriding to the relatively recently developed plasma nitriding. The latter has replaced the process of “soft nitriding” in the automotive industry based on nitrocarburizing in cyanide salt baths. It seemed that the high toxicity of the initially used compositions for soft nitriding (Tufftride or Tenifer) should have eliminated salt baths from the industry. However, they are still rather widely used. The replacement of old compositions by nontoxic ones has solved fundamental problems of environment protection. Low-temperature nitriding technology also advanced considerably. Salt bath nitriding is a very active process, more intense than that of gas nitriding and nitrocarburizing including the processes of plasma nitriding. The reactivity of the nitriding medium and the final efficiency of the process with allowance for the cost of the equipment have to be taken into account. An additional advantage of salt bath nitriding is the possibility of treatment of stainless maraging steels. The present work is devoted to comparison of the processes of treatment in a nontoxic salt bath and in a gas medium and discussion of the advantages of nitriding in nontoxic salt baths.     

微碳铬铁渗氮的动力学研究

氮能提高某些钢种的耐磨性和抗疲劳性,在不锈钢中氮还可代替镍,而氮化铬铁合金中的氮是含氮钢冶炼中主要氮源之一。本课题对固态微碳铬铁合金在高温电阻炉中气体（氨气和氮气）渗氮的动力学进行了研究。通过改变各种渗氮条件,可以发现合金氢化时的温度对铬铁合金氮化速率及氮含量有很大影响;并且随着合金颗粒度减小,渗氮速率加快;在相同条件下氨气的渗氮效果要远远好于氮气。研究结果为最终获得好的渗氮效果提供了数据和方法。     

不锈钢低温渗氮/渗碳S相渗层技术的研究进展

奥氏体不锈钢通过低温渗氮/渗碳,获得含氮/碳固溶饱和的扩散层,即S相渗层,不仅提高了不锈钢表面硬度,而且还提高了不锈钢的耐蚀性。本文综述了不锈钢S相渗层研究与应用技术的最新研究进展,分析了低温离子渗氮/渗碳、气体低温渗氮/渗碳、高温渗氮固溶淬火及离子注入渗氮技术的工艺特点。讨论了S相渗层的力学性能和耐蚀性能,分析了国内S相低温渗层技术工业应用存在的问题,展望了S相技术的发展前景。     

Effect of Electric Potentials on Microstructure,Corrosion and Wear Characteristic of the Nitrided Layer Prepared on 2Cr13 Stainless Steel by Plasma Nitriding

Plasma nitriding is a widely used technology to enhance the surface performance and extend the service life of alloy parts.The current research mainly focuses on the influences of time, temperature, gas type and pressure parameters on nitriding behavior, while fewer studies have been conducted on the electric potential. This paper mainly reports the effect of the electric potential on nitriding behavior. Test conditions were set using cathodic, anodic and floating potentials in a plasma nitriding furnace. 2Cr13 stainless steel was nitrided at 450 °C for 5h in an NH_3 atmosphere. The experimental results show that the nitriding treatment can be well performed under the different electric potentials, but differences exist in microstructures, morphologies and performance results of the modified layers. The thickness and hardness values of the nitrided layer are ranked as follows: cathodic [ anodic [ floating potential. The anodic nitrided surface has an obvious particle deposition layer composed of nitrides and oxides. Electrochemical and tribological experiments show that the corrosion resistance and wear resistance were significantly improved after a nitriding treatment using the three electric potentials. Moreover, the floating nitriding treatment resulted in the best tribological performance and corrosion resistance.     

离子渗氮对304L不锈钢组织及高温耐磨性能的影响

以焚烧炉用热电偶304L不锈钢套管为研究对象,开展了不同温度的离子渗氮试验研究。采用光学显微镜、扫描电镜、显微硬度计等分析了304L不锈钢离子渗氮前后的微观结构与力学性能,并研究了其在400 ℃的耐磨损性能。结果表明,304L不锈钢离子渗氮后,可形成硬度1300 HV以上的表面硬化层。随着渗氮温度的提高,表面硬度有所提升,同时硬化层厚度显著增加。离子渗氮可提高304L不锈钢的磨损性能及耐高温氧化性能。     

氮化处理改善1Cr18Ni9Ti钢在MgCl_2溶液中应力腐蚀破裂性能的研究

<正> 一、前言 利用表面处理作为防止不锈钢应力腐蚀破裂(SCC)的有效途径已得到人们的普遍重视。我们以1Cr18Ni9Ti钢为基材,分别进行了电镀Ni-P、喷铝、离子氮化等表面处理,然后在42％MgCl_2沸腾(143℃)溶液中作恒载荷拉伸试验,结果表明离子氮化处理对改善不锈钢抗SCC性能的效果最明显。     

Low temperature nitriding of AISI 316L stainless steel and titanium in a low pressure arc discharge

AISI 316L stainless steel (SS) and titanium nitriding were studied in a low pressure arc-assisted nitriding process where the substrate temperature and the plasma parameters are uncoupled. Lower nitriding temperature limits were explored for constant plasma parameters in Ar–N₂ gas mixtures and substrates at floating potential. Nitrogen superficial concentration, layer thicknesses and X-ray diffraction analyses were performed on SS specimens nitrided at two temperatures (580 and 680 K) for different times and titanium nitriding was studied in the temperature range 750–1025 K. At low temperature, the nitriding performances are limited by a plasma–surface phenomenon that probably involves recombination of nitrogen atoms.     

304奥氏体不锈钢氮离子注入层的组织与性能研究

对具有抗磁性的304奥氏体不锈钢进行离子渗氮处理,以提高其硬度和耐磨性.研究了奥氏体不锈钢渗氮前后的金相组织、显微硬度、耐磨性和耐腐蚀性等,并与常用高硬度、高耐磨性GCr15钢进行了对比.结果表明:304奥氏体不锈钢通过一定时间的离子渗氮后,依然具有很好的抗磁性能,且表层硬度约为基体硬度的6倍,耐磨性能大大提高,其性能...