不锈钢真空钎焊

简述了不锈钢真空钎焊技术的应用、原理、工艺及设备情况,并概述了不锈钢真空钎焊技术的发展趋势.     

高温熔融玻璃介质中耐热不锈钢腐蚀行为EI北大核心CSCD

核工业发展及核能的不断开发促使人们开始大力研究绿色环保且安全的核废料处理技术。利用金属容器填装玻璃固化核废料并进行填埋是目前国际上主流的核废料处理技术之一。然而,高温熔融玻璃对金属容器表面产生的高温腐蚀成为加速容器失效的重要原因。因此,深入理解金属在高温熔融玻璃介质中的腐蚀行为是保障核废料安全处理的关键之一。本研究选用S30815耐热不锈钢作为研究对象,深入分析S30815耐热不锈钢在1100℃熔融玻璃中保温不同时间后材料表面腐蚀形态、成分及物相结构。研究结果表明,熔融玻璃首先沿晶界向内腐蚀,然后逐步替代金属材料占据晶界位置并进一步向晶内扩渗,形成腐蚀坑。耐热不锈钢中的Cr,Si元素在腐蚀过程中向熔融玻璃扩渗并导致金属表层元素含量下降,最终促使金属表面由奥氏体转变为马氏体。熔融玻璃对耐热不锈钢的腐蚀属于碱性溶解,金属表面无法形成连续稳定的氧化膜,因此,随着保温时间延长腐蚀将会不断进行。     

酸性盐溶液中复合缓蚀剂对304不锈钢缓蚀作用的研究

为了研究不同缓蚀剂及复合型缓蚀剂对304不锈钢在酸性(pH=1)3.5%氯化钠溶液中的最佳缓蚀效果、最佳复配效果和最佳复配比例,采用失重法、电化学方法、表面形貌观察法、表面接触角和表面张力等表征方法对咪唑、硫脲、铬酸钾这三种物质的缓蚀效果及复配效果进行了研究.结果表明:失重法和表面形貌观察法均显示出三种物质都有一定的缓蚀效果,其缓蚀效率的大小关系为:硫脲铬酸钾咪唑,最佳缓蚀时间为24 h;通过极化曲线Tafel外推法、电化学阻抗谱法和表面形貌观察法等均可得出最佳复配效果为硫脲与铬酸钾复配;将100 ppm的硫脲5 mL和100 ppm的铬酸钾5 mL进行复配时(复配比为1∶1)通过表面接触角和表面张力的方法可得最小接触角为46.5°,最小表面张力71.9 mN/m,故最佳复配比为1∶1,即在硫脲与铬酸钾配比为1∶1且时间为24 h时,这种复合型缓蚀剂对304不锈钢的缓蚀效果最佳.     

Ferritic stainless steel — A coinage material

General economic and metallurgical requirements, and processing methods for coinage materials are reviewed. The Indian effort at the development of ferritic stainless steels for coinage is discussed. The results of several trials at the Salem Steel Plant towards establishing the appropriate composition and processing route are presented and evaluated.     

Spectral-directional emittance of thermally oxidized 316 stainless steel

The spectral-directional emittance of thermally oxidized stainless steel is measured for angles from normal to grazing, wavelengths between 2 and 10m, and temperatures between 773 and 973 K. The oxide is grown by holding the steel substrate at a high temperature over a long period while exposed to normal atmospheric conditions, until the measured emissive power of the surface achieves an asymptotic level. It is found that the emittance decreases with angle away from the surface normal at the lower end of the measured spectral range and increases with angle at the higher end. The emittance decreases with wavelength, although there is evidence of a peak near 2 pill. The variation with temperature within the measured range is insignificant. Overall higher values for the oxidized steel are measured than those reported in previous work.     

Preparation and biological evaluation of hydroxyapatite-coated nickel-free high-nitrogen stainless steel

Abstract

Calcium phosphate was formed on nickel-free high-nitrogen stainless steel (HNS) by chemical solution deposition. The calcium phosphate deposition was enhanced by glutamic acid covalently immobilized on the surface of HNS with trisuccinimidyl citrate as a linker. X-ray diffraction patterns and Fourier transform infrared spectra showed that the material deposited on glutamic acid-immobilized HNS within 24 h was low-crystallinity calcium-deficient carbonate-containing hydroxyapatite (HAp). The biological activity of the resulting HAp-coated HNS was investigated by using a human osteoblast-like MG-63 cell culture. The HAp-coated HNS stimulated the alkaline-phosphate activity of the MG-63 culture after 7 days. Therefore, HAp-coated HNS is suitable for orthopedic devices and soft tissue adhesion materials.     

Preparation and biological evaluation of hydroxyapatite-coated nickel-free high-nitrogen stainless steel

Calcium phosphate was formed on nickel-free high-nitrogen stainless steel (HNS) by chemical solution deposition. The calcium phosphate deposition was enhanced by glutamic acid covalently immobilized on the surface of HNS with trisuccinimidyl citrate as a linker. X-ray diffraction patterns and Fourier transform infrared spectra showed that the material deposited on glutamic acid-immobilized HNS within 24 h was low-crystallinity calcium-deficient carbonate-containing hydroxyapatite (HAp). The biological activity of the resulting HAp-coated HNS was investigated by using a human osteoblast-like MG-63 cell culture. The HAp-coated HNS stimulated the alkaline-phosphate activity of the MG-63 culture after 7 days. Therefore, HAp-coated HNS is suitable for orthopedic devices and soft tissue adhesion materials.     

Carbon deposition on stainless steel in oxidising environments

Abstract

The formation of low-density carbon deposits onto metallic heat transfer surfaces in industrial environments of high carbon activity can have a deleterious effect on thermal efficiency. Often this deposition occurs under reducing conditions and involves carbide (typically of iron) formation as part of the process. It is possible, however, for filamentous carbon deposits to form at much higher oxygen potentials where carbide formation is not favoured thermodynamically. This study considers one such situation by examining the behaviour of a 20Cr25Ni austenitic steel used as fuel cladding in Advanced Gas-cooled nuclear reactors (AGRs). Carbon deposition has been produced in laboratory by exposure at 550°C to CO₂ containing 1%CO and 1000 vppm C₂H₄; the dissociation of the latter additive generates carbon activities much greater than unity. The oxygen potential of this gas is sufficient to oxidise iron and chromium, of the major alloy constituents, but not nickel. The deposition takes place onto substrates that are prepared as electron microscope samples which are subsequently examined by SEM and HREM (high resolution electron microscopy) techniques. The deposits formed consist of solid carbon filaments, approximately 30 nm in diameter, with turbostratic atomic layering. Each filament contains a 10–20 nm metallic nickel particle near its tip. It is argued, and supported by HREM evidence, that such particles are produced as a direct result of the oxidation of the alloy and that prior oxidation is necessary to produce the observed carbon deposition. It is also shown that inhibition of carbon deposition occurs when the oxygen potential of the depositing gas is increased sufficiently to oxidise nickel.     

Corrosion fatigue behaviour of 304 stainless steel under proportional and non‐proportional multiaxial loading condition

Corrosion fatigue and electrochemical tests under proportional loading and non‐proportional loading were conducted on 304 stainless steel in 0.63 mol L^?1 NaCl solution at room temperature. Two biaxial loading paths were applied to study the effect of proportional loading and non‐proportional loading on corrosion fatigue behaviour. Surface and fractographic observations of multiaxial corrosion fatigue specimens were carried out by scanning electron microscopy. It was shown that proportional loading had a more significant effect on the occurrence of local corrosion compared with non‐proportional loading because the continuous rotation of the principal stress plane under non‐proportional loading inhibits the pit formation.     

双电极奥氏体不锈钢焊条单弧焊工艺研究

本文研究了双电极奥氏体不锈钢焊条单弧焊电弧的静特性、焊接电流、电弧电压、焊芯间隙对双电极焊条单弧焊的工艺性能和焊缝成形的影响;通过热电偶测试技术,对双电极焊条单弧焊焊接过程中不同部位焊芯表面温升进行了测定.研究结果表明焊芯直径为φ4.0mm的双电极A102焊条,其合适焊接工艺参数为:焊接电流140～160A,电弧电压45V左右,焊条两芯间隙1.2～1.5mm,焊接板厚8mm的1Cr18Ni9Ti材料,焊缝成形良好.     

Corrosion in water supply pipe stainless steel 304 and a supply line of helium in stainless steel 316

A corrosion spreading throughout the 304 stainless steel tubing of a water system to supply various buildings was observed, and also leaks were detected in welding zones. The same place is also crossed by a gas distribution network, with a helium pipe 316 of stainless steel that required periodic repairs more or less every two years, due to the presence of leaks. The tests showed that both types of stainless steel have suffered localized corrosion induced by hypochlorite ion, in a mechanism of dry/wet, and that the welding procedure performed on the 304 stainless steel is unacceptable. Some immediate procedures were undertaken to keep systems running, but recommendations were given for a final resolution of the problems.     

Cr-Ni-Mo双相不锈钢的空泡腐蚀行为

利用超声波空蚀实验装置对Cr-Ni-Mo奥氏体-铁素体不锈钢及其同质材料堆焊后的堆层金属在自来水溶液中的空蚀行为进行了研究.通过扫描电镜（SEM）、显微硬度计等检测设备研究了材料空蚀表面形貌和微观结构.结果表明：Cr-Ni-Mo双相不锈钢的抗空蚀性能明显优于经TIG（钨极惰性气体保护焊）表面堆焊后的堆层金属试样;双相不...     

Fretting fatigue behaviour of Ni-free high-nitrogen stainless steel in a simulated body fluid

Abstract

Fretting fatigue behaviour of Ni-free high-nitrogen steel (HNS) with a yield strength of about 800 MPa, which was prepared by nitrogen gas pressurized electroslag remelting, was studied in air and in phosphate-buffered saline (PBS(-)). For comparison, fretting fatigue behaviour of cold-rolled SUS316L steel (SUS316L(CR)) with similar yield strength was examined. The plain fatigue limit of HNS was slightly lower than that of SUS316L(CR) although the former had a higher tensile strength than the latter. The fretting fatigue limit of HNS was higher than that of SUS316L(CR) both in air and in PBS(-). A decrease in fatigue limit of HNS by fretting was significantly smaller than that of SUS316L(CR) in both environments, indicating that HNS has better fretting fatigue resistance than SUS316L(CR). The decrease in fatigue limit by fretting is discussed taking into account the effect of friction stress due to fretting and the additional influences of wear, tribocorrosion and plastic deformation in the fretted area.     

一种新型铁素体不锈钢的深冲性能研究

为探究一种新型铁素体不锈钢的深冲性能,在840~920℃不同温度下对新型铁素体不锈钢的冷轧板做再结晶退火处理,通过XRD、SEM和EBSD等分析方法研究了退火2 min或4 min后,材料微观组织、宏观织构的变化规律对深冲性能的影响及其内在机理.研究表明:保持退火时间2 min,退火温度900℃时,试验钢拥有较多的有利γ纤维织构,主要为{111}112取向,并有少量α纤维织构,此时平均塑性应变比r-=1.77,高于其他退火温度下的值;延长退火时间,在900℃下保温4 min,不同取向晶粒获得了长大机会,晶粒尺寸均匀性显著改善,r-值提高至1.82,试验钢有望取得理想深冲性能.     

Corrosion and cracking characteristics upon aging of hyper duplex stainless steel weld

ABSTRACT

In this study, the effects of Mo content and aging temperature on the corrosion characteristics of newly designed hyper duplex stainless steel welds were investigated. Each specimen was aged at 600°C for 1–100?h, and weld cracking occurred when the 6?wt-% Mo specimen was aged for more than 40?h. In addition, electron backscatter diffraction and X-ray diffraction analysis found that the number of secondary phases increased as aging time increased. Based on the potentiodynamic polarisation test for assessing the corrosion characteristics according to the aging time, the corrosion resistance decreased sharply after 40?h, when cracking occurred.

Highlights

• When aging treatment for more than 40?h was performed on 6?wt-% Mo specimen, weld crack occurred.

• High hardness values above 450 Hv0.5 were measured in specimens aged more than 40?h.

• Secondary phases such as σ-phase and χ-phase were observed in specimens aged for more than 40?h.

• The specimens aged for more than 40?h showed a rapid decrease in corrosion resistance.

     

水雾化304L粉末材料的表面化学反应研究

研究了水雾化奥氏体不锈钢粉末在致密时的表面化学反应.研究发现颗粒表面和孔隙表面的化学反应受致密温度的强烈影响,材料的力学性能与表面化学反应产物及其形态和分布有关.     

表面纳米化与离子渗氮对304不锈钢的影响

为解决304不锈钢硬度低、耐磨性差的问题,本文采用预先表面纳米化,温度400、450℃,保温时间4、6 h,氮氢比1∶3的离子渗氮工艺对试样进行处理,研究纳米化以及渗氮工艺对304不锈钢渗氮层形貌和深度、硬度以及摩擦磨损性能的影响.利用金相显微镜、电子探针显微分析仪(EPMA)、能谱仪(EDS)、显微硬度计和磨损试验机对样品的显微组织、微观形貌、硬度及耐磨性进行了表征.结果表明:304不锈钢经表面纳米化与离子渗氮工艺处理后,渗氮层为0.1～0.2 mm,表面硬度约为1 200 HV0.1,比基体硬度提高了6～7倍,耐磨性也大大增强;但渗氮温度越高,保温时间越长,材料表面耐磨性越差.综合各种影响因素得出在本实验条件下最佳处理工艺为:预先表面纳米化,渗氮温度400℃、保温时间6 h.     

含Cu铁素体抗菌不锈钢的抗菌性能

含Cu铁素体抗菌不锈钢在抗菌热处理过程中析出ε-Cu相,具有抗菌功能.抗菌处理的条件影响析出相的数量和形貌,从而影响其抗菌特性.在时效温度较低时,抗菌析出相基本上呈球形,随着时效温度的升高,析出相逐渐变为长条形并与铁素体基体保持某种取向关系.在抗菌不锈钢抗菌过程的前期,抗菌性能表现为对细菌生长和繁殖的抑制,后期表现为对细菌的杀灭.     

赛普特不锈钢膜分离系统及应用

膜分离是近年发展较快的一门高新技术。叙述一种新型膜－赛普特不锈钢膜的基本结构和特性及其在各种领域的应用。     

温度对40Cr13钢等离子表面渗铌层组织的影响

为提高马氏体不锈钢的耐蚀和耐磨性能,选择40Cr13不锈钢为基材、纯铌板为靶材,采用双辉等离子表面冶金技术在不锈钢表面制备合金化层.用SEM、GDOES、XRD等方法分析渗铌温度对铌合金层组织、成分、相组成、表面形貌及硬度的影响,并对渗层形成机制及表面硬化机理进行了研究.结果表明:在900~1 000℃形成的铌合金层组织均匀致密,合金层主要由Nb2C、Nb C、Fe2Nb、Cr2Nb及铌组成;合金层表面粗糙度随渗铌温度的提高而增加;合金层厚度随渗铌温度改变发生不同变化规律,950℃渗铌形成的渗层约13μm,900和1 000℃渗铌后合金层厚度均为7μm左右;不同温度渗铌后试样的表面硬度与基体相比均有较大幅度的提高,1 000℃渗铌后试样表面硬度高达约985 HV0.025,900℃渗铌后约758 HV0.025,而950℃渗铌后表面硬度最低,约698 HV0.025.