硫碳氮三元共渗试验

任何机器的性能和寿命,在很大程度上都决定于一些主要摩擦零件表面金属薄层的状态,即主要决定于该层的耐磨性,因此,采用强化金属表面的方法是最合理的。     

碳氮共渗剂

对于表面要求硬而耐磨、芯部要求有良好的韧性、整体有满意的疲劳寿命的零件 ,最好采用低碳钢或经碳氮共渗处理过的低合金钢。（１）共渗剂欲进行碳氮共渗 ,首先应解决共渗剂的问题。共渗剂的配方各不相同 ,常用的有氨 煤油、甲醇 尿素 丙酮 ,以及三乙醇氨等几种。使用这些共渗剂 ,往往存在下面的问题 :或是附加设备多 ,或是原料供应困难 ,或是出现黑色组织 ,或是氮浓度太低 ,或是价格昂贵等等。因此必须研制简便而可靠的碳氮共渗剂。由于尿素在工业纯甲醇或酒精中的室温饱和溶解度分别为１５ %和１０ % ,所以直接采用此种溶液作共渗剂难…     

4Cr13不锈钢膏剂法低温氮碳共渗

一、前言 钢件在560℃左右氮碳共渗后,抗擦伤性能、疲劳强度和耐磨性大为提高,且处理时间较短,广泛应用于对调质、精加工后变形敏感的工件。 氮碳共渗有固体、液体和气体等方法。固体法又分粉末装箱法和膏剂法,它们各有优缺点。就单件、小批量生产规模而言,膏剂法较为经济,可以灵活地     

低、高温氮碳共渗的应用

由Fe-C相图可知,在723℃时α-Fe中C的最大溶量是0.02％;由Fe-N相图可知,在590℃时α-Fe中N的最大溶量是0.1％。因此,用铁基材料,在它们共渗温度590～723℃之间,都可进行氮碳共渗处理。其共渗层组织由表面到心部随N浓度变化主要有ε、γ′、γ、α等几个相。从工厂应用的角度出发,希望得到两个相:一个是ε相,即     

镍系低温用钢缺口韧性的研究

通过对材料的试验检测及金相与电子断口分析,总结出调质工艺、正火 调质及不同的加热与回火温度对LF3锻钢和LC3铸钢低温韧性的影响。为改善这2种钢低温韧性的稳定性提供了良好的方法。     

Cavitation erosion resistance of high nitrogen stainless steel in comparison with low N content CrMnN stainless steel

Abstract

The cavitation erosion (CE) of a high nitrogen stainless steel (HNS) and a low nitrogen CrMnN stainless steel in both distilled water and 3%NaCl solution at 20±1°C was investigated by using a magnetostrictive induced cavitation facility. The evolution of CE with test time was analysed by morphology observation by SEM and roughness measurement after different CE intervals. The possible phase transformation of austenite to martensite due to cavitation was analysed by XRD, and cross-sectional microhardness after cavitation was also measured to evaluate the work hardening ability. The role of corrosion was analysed by polarisation curve. The test results indicated that HNS had a relatively higher CE resistance than CrMnN steel, which was mainly attributed to its higher work hardening ability, thicker wok hardening layer and lower stacking fault energy. Different from that of the HNS, many tiny cracks could be clearly seen in the cross-section of eroded CrMnN steel especially at the ferrite zones. The pure erosion dominated the whole cavitation damage process, and the synergistic effect between corrosion and erosion was relatively small for both steels. The CE behaviour of HNS was relatively more sensitive to the corrosion media than that of CrMnN steel. Therefore, it should be a little bit careful when HNS was used in corrosive media.     

不锈钢垫片的磨削加工

介绍了组合砂轮磨削不锈钢垫片时砂轮对加工表面质量和磨削力的影响。     

高温高压阀门的带压堵漏

简述了高温高压阀门泄漏对生产的影响，分析了阀门泄漏的原因。通过一起成功的实例。介绍了在不停车条件下对高温高压阀门进行带压堵漏的技巧。     

Effects of temperature and pressure on stress corrosion cracking behavior of 310S stainless steel in chloride solution

310S is an austenitic stainless steel for high temperature applications, having strong resistance of oxidation, hydrogen embrittlement and corrosion. Stress corrosion cracking(SCC) is the main corrosion failure mode for 310 S stainless steel. Past researched about SCC of 310 S primarily focus on the corrosion mechanism and influence of temperature and corrosive media, but few studies concern the combined influence of temperature, pressure and chloride. For a better understanding of temperature and pressure's effects on SCC of 310 S stainless steel, prepared samples are investigated via slow strain rate tensile test(SSRT) in different temperature and pressure in NACE A solution. The result shows that the SCC sensibility indexes of 310 S stainless steel increase with the rise of temperature and reach maximum at 10 MPa and 160℃, increasing by 22.3% compared with that at 10 MPa and 80 ℃. Instead, the sensibility decreases with the pressure up. Besides, the fractures begin to transform from the ductile fracture to the brittle fracture with the increase of temperature. 310 S stainless steel has an obvious tendency of stress corrosion at 10 MPa and 160℃ and the fracture surface exists cleavage steps, river patterns and some local secondary cracks, having obvious brittle fracture characteristics. The SCC cracks initiate from inclusions and tiny pits in the matrix and propagate into the matrix along the cross section gradually until rupture. In particular, the oxygen and chloride play an important role on the SCC of 310 S stainless steel in NACE A solution. The chloride damages passivating film, causing pitting corrosion, concentrating in the cracks and accelerated SSC ultimately. The research reveals the combined influence of temperature, pressure and chloride on the SCC of 310 S, which can be a guide to the application of 310 S stainless steel in super-heater tube.     

Effect of contact pressure on fretting fatigue of austenitic stainless steel

The effect of contact pressure on fretting fatigue in solution-treated austenitic stainless steel was studied. With an increase in contact pressure, fretting fatigue life was almost unchanged at low contact pressures, however it decreased drastically at high contact pressures. At low contact pressures, stress concentration due to fretting damage occurred at the middle portion of the fretted area and the main crack responsible for failure was initiated there. At high contact pressures, concavity was formed at the fretted area without accompanying heavy wear. The main crack was initiated at the outer edge corner of the concavity which probably acted as a notch. Plain fatigue prior to the fretting fatigue test increased the fretting fatigue life at high contact pressures since the concavity formation was suppressed by the cyclic strain hardening.     

Erosion–corrosion and corrosion properties of DLC coated low temperature gas-nitrided austenitic stainless steel

Low temperature nitriding of stainless steel leads to the formation of a surface zone of so-called expanded austenite, i.e. by dissolution of large amounts of nitrogen in solid solution. In the present work the possibility of using nitrogen expanded austenite “layers” obtained by gaseous nitriding of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature nitriding dramatically reduces the amount of erosion–corrosion of stainless steel under impingement of particles in a corrosive medium.     

全模拟油田深井高温超高压射孔效能试验装置研制

在石油开采过程中,射孔器材的改进和射孔工艺的改善对提高油田采收率和稳定油田产能具有重要意义。为评价射孔器材和射孔工艺的效能,在地面上建立了一套可对较深地层环境全模拟的高温超高压模拟井射孔试验装置。通过合理选用材料及结构设计,该装置能够模拟地下三维空间受压状态,进行多发弹射孔和流动性测试试验。文中对大直径超高压容器及其内部三腔压力分隔结构、温度和压力控制系统等作了介绍,对主要受压元件设计结构进行了强度、刚度的有限元分析计算。试验结果表明:该装置能够较好地模拟井下作业环境,为射孔效能评估分析研究提供了可靠的试验手段。     

不锈钢的ELID磨削实验研究

在实验的基础上,对磨削不锈钢时磨削力的变化规律进行分析,并将磨削力、工件表面粗糙度与普通磨削进行比较.结果表明,采用铸铁基金刚石砂轮进行ELID磨削时,磨削力随时间的增加量较小,而采用普通磨削方式进行磨削时,磨削力随时间的增加量较大.在线电解修整使砂轮在磨削中始终保持良好的磨削状态,有利于节省砂轮修整时间,提高加工效率.采用相同砂轮进行磨削实验,ELID磨削可获得更低的表面粗糙度值,实现了对不锈钢的精密镜面磨削.     

Influence of temperature on the fretting response between AISI 301 stainless steel and AISI 52100 steel

Fretting of AISI 301 stainless steel sheet in contact with AISI 52100 steel from 20 °C to 550 °C in air and argon has been studied. Transitions in the mechanical properties of 301SS and oxidative behavior of this pair have been identified as a function of temperature. Strength and ductility of 301SS is reduced from 20 °C to 250 °C, increasing susceptibility to fretting damage. Steady state friction decreases as temperature increases, reducing cyclic stresses. Wear resistance increases in this temperature range, increasing fatigue damage due to the increase in fatigue life associated with increased wear. This study aims to identify the causes of the transitions in behavior and determine the net outcome of the competing effects with regard to fatigue damage.