不锈钢焊接冶金的研究进展

介绍了奥氏体不锈钢焊缝中铁素体含量、母材和焊缝中合金元素对焊接接头性能的影响，同时还介绍了双相不锈钢、铁素体不锈钢、马氏体不锈钢焊接冶金的研究进展，并指出了研究不锈钢焊接冶金的重要意义。     

Effect of Sintering Temperature and Atmosphere on Nonlubricated Sliding Wear of Nano-Yttria-Dispersed and Yttria-Free Duplex and Ferritic Stainless Steel Fabricated by Powder Metallurgy

The nonlubricated sliding wear behavior of nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel against a diamond tip was studied. The stainless steel samples were fabricated by a conventional powder metallurgy route in which nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel powders were cold compacted and then conventionally sintered at either 1000, 1200, or 1400°C in an argon atmosphere. For comparison, another set of samples was sintered at 1000°C in a nitrogen atmosphere. The wear behavior of sintered stainless steel samples against a diamond indenter was investigated using a pin-on-disc apparatus at 10 and 20 N loads and at a constant speed of 0.0041 m/s. It is proposed that yttria-dispersed stainless steels showed higher wear resistance compared to yttria-free stainless steel due to their improved hardness and density. Stainless steel sintered in a nitrogen atmosphere exhibited better wear resistance than those sintered in an argon atmosphere due to the formation of hard and brittle Cr₂N. The wear mechanisms of stainless steels against diamond were found to be mainly abrasive and oxidative. Semiquantitative analysis of the worn surfaces and wear debris confirmed the occurrence of oxidation processes during wear.     

Influence of work material proof stress and tool steel microstructure on galling initiation and critical contact pressure

EN 1.4301 (austenitic), EN 1.4509 (ferritic), EN 1.4162 (duplex) and EN 1.4310 C1000 (metastable austenitic) stainless steels were tested in lubricated sliding against an ingot cast EN X153WCrMoV12 and powder metallurgy nitrogen alloyed Uddeholm Vancron 40 tool steels to reveal critical to galling contact pressure, P_cr. The calculated P_cr were higher for steels with higher strength. At P>P_cr, due to plastic flow of sheet material, the tool is damaged substantially and wear-induced matrix damage causes rapid galling initiation. At P<P_cr, galling was not observed. The powder metallurgy tool steel was more resistant to galling against all tested stainless steels. Better performance was associated with fine and homogeneously distributed hard phases preventing intensive wear of the tool steel matrix.     

Galling resistance evaluation of tool steels by two different laboratory test methods for sheet metal forming

Adhesive accumulation of work material on the tool surface is today a major problem in many sheet metal‐forming applications. Different laboratory test methods are used to investigate galling with respect to different tool materials, lubricants and process conditions. In the present study, the galling resistance of a modern nitrogen‐alloyed powder metallurgy tool steel and an conventional ingot cast D2 type tool steel was evaluated under lubricated sliding against ferritic stainless steel sheets using a commercial pin‐on‐disc (POD) and an in‐house made slider‐on‐flat‐surface (SOFS) tribotester. The investigated tool steels ranked similarly in terms of galling resistanc in both test methods. However, sliding distances to galling were longer for the SOFS equipment due to continuous sliding on new lubricated sheet surface. Best performance was demonstrated by the powder metallurgy tool steel treated to 65 HRC. Differences in friction behaviour and galling initiation were analysed on the basis of the two different working conditions, i.e. open (SOFS) and closed (POD) tribosystems. Copyright © 2012 John Wiley & Sons, Ltd.     

高压预冷器2205异种钢焊接制造工艺技术探讨

某天然气处理厂的高压预冷器,采用固定薄管板结构,由于管程介质中Cl-含量较高,管箱材质采用2205双相钢复合钢板,管板采用2205双相钢纯材,壳程材质为16MnR(或09MnNiDR)。阐述和分析了管板与管箱、壳程在焊接制造过程中遇到的技术难题和采取的有效措施,从而为双相钢设备的焊接制造提供经验。     

Effect of sliding wear on tribocorrosion behaviour of stainless steels in a Ringer's solution

The dependence of the tribocorrosion of stainless steels AISI 304L and SS 3M^® orthodontic archwires sliding against corundum in a Ringer's solution on applied normal force, and sliding velocity, has been investigated using in situ electrochemical noise measurements. Applied normal force and sliding velocity were found to greatly affect current and potential during fretting-corrosion. An increase in normal force and sliding velocity induce an increase in current and a decrease in potential accelerating the depassivation rate of the tested stainless steels. The fluctuations in potential and current during fretting-corrosion are more pronounced at increasing sliding frequency than at increasing applied normal force. Sliding wear affects the repassivation behaviour of the tested materials by increasing the anodic current in the wear track area.     

粉末冶金工艺制备不锈钢的研究进展

制备不锈钢的粉末冶金工艺与传统熔炼工艺相比具有成本低的优势,其生产的零件接近净成形且尺寸精度较高。主要介绍了近年来国内外利用粉末冶金工艺制备不锈钢的研究进展,包括烧结理论、成形和烧结技术的发展及成分添加剂对不锈钢组织和性能的改善。最后结合粉末冶金不锈钢的应用现状,提出了今后研究应重点关注的方向。     

双相不锈钢S31803的焊接性研究

焊接双相不锈钢S31803时容易出现焊接裂纹、热影响区脆化以及形成气孔等问题.文中从化学成分、组织状态、焊接冶金方面研究双相不锈钢S31803的焊接性,提出了合理选择焊接材料和制定焊接工艺的优化焊接性的途径.     

不同环境介质下氧化铝陶瓷与耐蚀金属摩擦磨损行为

为优选海水淡化高压泵关键零部件耐磨性能材料,以Al_2O_3陶瓷与TC4钛合金、316不锈钢、2205双相不锈钢组成的配对摩擦副作为研究对象,利用立式万能摩擦磨损试验机开展干摩擦、纯水及海水3种环境介质下配对材料的摩擦磨损试验,定量得到各摩擦副摩擦因数、磨损量,并对摩擦试样的表面形貌进行分析;采用正交试验法分析载荷、转速、环境介质对摩擦因数和磨损量的影响规律。结果表明:在相同的条件下,TC4钛合金与陶瓷配副摩擦因数较小,2205双相不锈钢与陶瓷配副磨损量较小;环境介质对摩擦因数影响较大,载荷对磨损量的影响较大;海水环境下2205双相不锈钢和316不锈钢磨痕较浅,磨损机制为疲劳磨损、磨粒磨损和腐蚀磨损的交互作用。     

Application of Taguchi coupled Fuzzy Multi Attribute Decision Making (FMADM) for optimizing surface quality in turning austenitic and duplex stainless steels

In the present study, Taguchi approach is coupled with fuzzy-multiple attribute decision making methods for achieving better surface quality in constant cutting speed face turning of EN 1.4404 austenitic, EN 1.4462 standard duplex and EN 1.4410 super duplex stainless steels. Two typical multiple attribute decision making techniques were simultaneously adopted to determine multi-surface quality characteristics indices. The differences in rankings among derived indices are solved through converting each crisp values into trapezoidal fuzzy number and unifying them using fuzzy simple additive weight method. The fuzzy numbers are then deffuzified into crisp values employing techniques like; the spread, mode and area between centroid of centroids. Through this procedure, the decision maker is provided with necessary decision tools to optimize the cutting conditions with less sensitivity to the change of weights and no difference in ranking among the deffuzification techniques. Additionally, results of analyses of means and the validation experiments confirm that the optimum cutting conditions derived by this method produce far better surface finish than the best finish obtained during the course of experimentation. Analyses of variance results have shown the predominant effect of feed rate on surface quality. Finally, the collected chip at constant cutting speed and varying feed rates and depth of cuts has shown that friendlier-to-machine chips are obtained when machining austenitic stainless steels than duplex stainless steel grades.     

Abrasive wear behaviour of sintered composite austenitic stainless steels having γ-Fe and M23C6 phases

Abstract

Using powder metallurgy, composites of austenitic stainless steel were produced along with unreinforced stainless steel mixed with titanium, cobalt and molybdenum particles. Wear resistance of the materials was measured by a two body pin on disc wear tester. SiC abrasive papers of 80 and 220 mesh sizes were used as abrasive media. Wear tests were performed under loads of 10, 20 and 30 N at room temperature. The abrasive wear measurements showed that the softer, unreinforced austenitic stainless steel exhibited higher mass loss than the composites. Furthermore, the abrasive wear resistance of the reinforced austenitic stainless steel composites increased with increasing FeTi, FeMo, or Co volume content. In addition, the wear rate against the 80 grade SiC abrasive paper increased more than against the 220 grade SiC abrasive paper.     

不锈钢在压力容器中的应用及焊接技术(一)

通过对我国20世纪尿素不锈钢的焊接、腐蚀性能的研究及大型尿素设备、双相钢设备和高级不锈钢设备及管道的制造与焊接技术的回顾，介绍不锈钢在一些典型压力容器中的应用并展望其扩大应用的前景。     

Revision of cavitation erosion database and analysis of stainless steel data

Cavitation erosion data have been accumulated in our laboratory for about 32 years since 1970. The database was constructed as electronic data in MS Excel files. The data files are able to offer quick search in terms of the test material, test method and test conditions from among 859 data. In this study, 131 data since 2003 were newly added to the database constructed in our previous study. The stainless steel data were analyzed, including various stainless steels such as ferritic, austenitic, duplex and martensitic stainless steels. Vibratory cavitation test results for different stainless steels, obtained with varying test conditions of frequency, amplitude and attachment of specimen, were converted analytically to obtain average erosion rates under assumed standardized conditions of a stationary specimen test with 1 mm standoff distance, and with frequency and amplitude as specified by ASTM G32. The average of erosion rate under the standardized condition (ASTM G32, stationary specimen method, standoff distance 1 mm) was determined for different stainless steels. The erosion resistance was defined as a reciprocal of erosion rate, and the correlation between erosion resistance and hardness of the specimen after erosion test was better than with the other mechanical properties. The erosion resistance is equal to 2.6E?07 × (HV × F_mat)^2.4 (HV; Vickers hardness, F_mat; material factor), and the correlation coefficient is 0.98. It was concluded that the erosion resistance of different stainless steels could be estimated with high reliability from the material hardness and the material factor.     

The abrasive-corrosive wear of stainless steels

Laboratory abrasive and abrasive-corrosive testing has been carried out on a range of ferritic, austenitic and martensitic stainless steels and the results compared with the testing of similar materials in situ in the abrasivecorrosive conditions of a gold mine. All grades were found to have better abrasive-corrosive resistance than proprietary abrasion-resistant alloys.The austenitic grades derive their outstanding properties from their capacity to resist unstable fracture of microshear lips on the abraded surface. This is due to the strain capacity afforded by the mechanical inducement of the martensitic phase transformations and the high work-hardening characteristics of the transformation product. The influence of this transformation has been studied as a function of prior cold work and velocity of abrasion on a range of austenitic grades of stainless steels.Notwithstanding these advantages of the austenitic grades, the ferritic grades are superior in terms of cost per unit volume lost and the new duplex ferritic-martensitic steel designated 3CR12 has potential as an abrasionresisting material in corrosive environments.     

Adhesive and abrasive wear behaviour of TiC alloyed,sintered, austenitic stainless steels

Abstract

This study examines abrasive and adhesive wear behaviour of austenitic stainless steel and its TiC alloyed composite produced through powder metallurgy technique. Abrasive wear tests have been carried out using a pin on disc wear tester under loads of 10, 20 and 30 N. For adhesive wear tests, a block on ring wear tester has been used under loads of 20, 40, 60 and 80 N. A possible correlation between the hardness, microstructure and wear behaviour of the samples has been investigated. The abrasive wear tests have revealed that the highest rate of mass loss occurred in the austenitic matrix stainless steel sample; also, mass losses decreased with an increased rate of reinforcing material in the composite. In adhesive wear tests, interparticle spacing developed from severe wear and extreme plastic deformation under heavy loads; however, at low loads, oxidation type wear was shown to be dominant.     

Wear characteristics of ceramic cutting tools in machining steel

Some ceramic materials such as Al₂O₃ which have a high compressive strength, hardness and chemical stability came into use industrially in the middle of this century as powder metallurgy produced indexable cutting tool inserts. These early ceramic tools were inherently weak in tension, impact and dynamic loading owing to their low tensile strength, toughness and transverse rupture strength; because of this their application was limited to medium productivity operations and work materials of softer grades. However, the technology of ceramic cutting tools has made great strides in the last few years through substantial improvements in their strength, toughness and wear resistivity. These modern ceramic tools have found wide and economic applications in high production machining of both cast iron and steels.In this paper the constructional characteristics of some modern ceramic tools and their wear behaviour and overall performances in machining mild steel at both low and high speeds are presented. The comparative results obtained are reported and discussed.     

Wear Mechanisms in Galling: Cold Work Tool Materials Sliding Against High-strength Carbon Steel Sheets

Transfer and accumulation of adhered sheet material, generally referred to as galling, is the major cause for tool failure in sheet metal forming. In this study, the galling resistances of several tool steels were evaluated against dual-phase high-strength carbon steel using a SOFS tribometer, in which disc-shaped tools were slid against a real sheet surface in dry sliding test conditions. Three different frictional regimes were identified and characterized during sliding, and any transition in friction corresponded to a transition in wear mechanisms of the sheets. The performance of the tools depended on load, material and the particular frictional regime. Best overall performance was obtained by nitrogen-alloyed powder metallurgy tool steel.     

Influence of friction on the local mechanical and electrochemical behaviour of duplex stainless steels

The electrochemical behaviour of ferritic and austenitic phases in duplex stainless steel (UNS S32304) and the modifications induced by straining during sliding were studied by potentiodynamic polarisation curves determined at the microscale in a 1 M NaCl (pH 3) solution, using an electrochemical microcell. The mechanical properties and stress state of each phase were determined by microhardness and X-ray microdiffraction measurements, before and after straining. The results show that sliding generates elastic straining of the ferrite and plastic deformation of the austenite. The electrochemical behaviour of these phases is dramatically altered, inducing a reduction of the corrosion resistance and of the passivation properties.     

Characterization of Passive Films Formed on As-received and Sensitized AISI 304 Stainless Steel

The current research of corrosion resistance of stainless steels mainly focuses on characterization of the passive films by point defect mode and mixed-conduction model. The corrosion resistance of the passive films formed on asreceived and sensitized AISI304 stainless steel in borate bu er solution were evaluated in this paper. The degree of sensitization and corrosion resistance of AISI304 stainless steels was evaluated by double loop electrochemical potentiodynamic reactivation and electrochemical impedance spectroscopy. The passive films formed on the stainless steels were studied by XPS technique. It was found that as-received specimen had higher pitting corrosion potential and corrosion resistance than sensitized one. The Mott-Schottky results showed that sensitized stainless steel had more defects in the passive film than as-received one. The compositions of the passive films were mainly Cr and Fe oxides according to XPS results.     

Microstructural aspects determining the adhesive wear of tool steels

In many machining applications, adhesion of the workpiece to the tool is a major problem. Adhesion may be reduced by changing the microstructure of the tool steel, e.g. by increasing the carbide content. The present work deals with the influence of some microstructural parameters in the adhesive wear of tool steels. The investigations were conducted using six model alloys based on the powder metallurgy high speed steel AISI M4, all of which had the same martensitic matrix composition after heat treatment. The alloys had MC carbide contents which varied between 0 and 25 mol% in 5 mol% increments. Ball-on-disc experiments were carried out in ambient air at room temperature using austenitic stainless steel and aluminum balls as counterfaces. Wear tracks on the disks were characterized using both a scanning electron microscope and an optical profiler. The results show that two main parameters determine the adhesive wear behavior: the carbide content and the distance between carbides.