医用不锈钢的研究与发展

不锈钢由于具有优异的力学性能、耐蚀性能和加工性能而被广泛应用于各种医疗器械及手术工具的制造。概述了医用不锈钢的特点和临床应用,以及存在的主要问题,并以高氮无镍奥氏体不锈钢、不锈钢表面改性、抗菌不锈钢为重点,介绍了医用不锈钢近年来在国内外的主要研究进展。表明医用不锈钢的研究与发展,进一步提高或改善了不锈钢的生物安全性、力学性能、耐蚀性能,甚至带来了一些生物功能化,为医用不锈钢的临床应用带来了新的机遇。     

EFFECT OF NON-METALLIC INCLUSIONS ON CORROSION FATIGUE RESISTANCE OF P/M DUPLEX STAINLESS STEELS

Abstract— The effect of non-metallic inclusions on high-cycle fatigue resistance of powder metallurgically (P/M) fabricated and hot isostatically pressed (HIP) duplex stainless steels (DSSs) was investigated with axial fatigue test specimens in a chloride and sulphate containing aqueous solution at room temperature. The inclusion content of the studied materials was analysed with bulk oxygen content measurements as well as with optical and digital inclusion analysis methods. Fatigue crack initiation was observed to take place at material defects, i.e., on contaminated prior powder-particle boundaries or, especially, at oxide inclusions. Localised corrosion was not noticed at the initiation sites. Material defects had an especially pronounced effect on fatigue properties, when the stress ratio was R =0, but their effect decreased, when the calculated stress intensity factor was reduced below a certain value. Moreover, the change of the stress ratio from R =0 to R =-1 decreased the difference in high-cycle corrosion fatigue properties between P/M-HIP DSSs with different inclusion contents.     

Unexpected Corrosion Problems by Organic Fat Charged in Loading Tanks of a Cargo Ship

A failure analysis has been conducted on board a cargo ship to assess the extent of corrosion damage. The damage was classified as unusual by the ship owner since the material, an organic fat (namely tallow), was usually loaded into stainless steels on board tanks without any noticeable corrosion problems. The corrosion phenomenon was classified, by the technical crew, as pitting on the bottom of two tanks, particularly the 6p (port tank) and the 6s (starboard tank). The pitting was defined as anomalous since only two tanks were affected and a total of five tanks were made of same stainless steels and loaded with same organic fat mixture. Corrosion pits were found during final inspection by the captain, following load discharge and tanks cleaning operations. The initial inspection was carried out while the cargo ship was harboured at Algeciras (Spain). Because of the observations, the ship remained in harbour for 3 days awaiting inspection by qualified technicians to evaluate the possibility of resuming navigation. The cargo ship was then inspected by one of the authors in collaboration with two metallurgists acting as consultants to the ship owner. The purpose of the inspection was to investigate on damage phenomena, to evaluate the integrity of cargo structures and to decide on two possible options: resuming navigation or immediately ordering a very expensive stop for urgent maintenance. This paper was structured to show documentation (some details have been omitted for propriety reasons) and visual inspection results used to establish failure mechanisms and probable failure-root causes. These results enabled a decision for the cargo ship to resume travel to next dockyard for maintenance operations.

Nickel-free austenitic stainless steels for medical applications

Abstract

The adverse effects of nickel ions being released into the human body have prompted the development of high-nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel in medical stainless steels, the advantages of nitrogen in stainless steels, and emphatically, the development of high-nitrogen nickel-free stainless steels for medical applications. By combining the benefits of stable austenitic structure, high strength and good plasticity, better corrosion and wear resistances, and superior biocompatibility compared to the currently used 316L stainless steel, the newly developed high-nitrogen nickel-free stainless steel is a reliable substitute for the conventional medical stainless steels.     

Modelling tail effects in creep-crack initiation and growth for 316L stainless steel

For complex loading history (creep and fatigue) applied to engineering components, assessment procedures generally estimate the crack initiation and growth by using the summation of continuous fatigue and pure creep crack growth rates. This text deals with the pure creep correlation established in laboratory tests and applied to components subjected to creep-fatigue loading. The trend of the creep opening displacement history superimposed onto the crack progress is sufficient to predict what kind of tail effect will occur when plotting ? vs. C*. The exponent of this correlation is demonstrated to be very close to unity, whatever creep stage is concerned. The contribution of either the material behaviour or the crack extension to the ? -C* correlation is discussed.     

射频/直流磁控溅射316L不锈钢/陶瓷复合薄膜组织与性能的研究*

利用射频／直流磁控溅射法,制备了316L不锈钢／SiO2(Al2O3)复合膜,研究了薄膜的组织和形貌,测试了薄膜的显微硬度和耐磨性。结果表明,溅射316L不锈钢薄膜和316L／SiO2(Al2O3)复合薄膜都呈柱状晶结构,主要由Fe-Cr和γ-Fe相构成;溅射316L不锈钢薄膜在Fe-Cr（110）晶面出现明显择优取向;由于射频溅射陶瓷的掺合,使316L不锈钢／陶瓷复合薄膜柱装晶细化,并出现二次柱状晶,在Fe-Cr（211）晶面出现明显的掺优取向,尽管316L不锈钢／陶瓷复合膜的显微硬度相对于磁控溅射316L薄膜提高不大,但其抗磨损性能明显提高,以316L／Al2O3复合膜尤为显著。     

0Cr13Ni5Mo/Q345C马氏体不锈钢复合板的焊接性

分析了 0Cr13Ni5Mo/Q345C马氏体不锈钢复合板的焊接性。通过抗裂性试验、复合板补焊及复合板对接焊、焊接工艺评定 ,提出了该复合板配套的焊接材料及可行的焊接工艺 ,按此工艺焊接的 0Cr13Ni5Mo/Q345C复合钢板接头的力学性能满足技术指标的要求。     

Factors affecting the oxidation mode of stainless steels

Abstract

Studies have been made to investigate what effect different factors have on oxide formation on stainless steels at 600–1,000°C in air. The factors include the effect of microstructure, airflow rate, surface preparations, residual oxides and variations of the dew point of the air. Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and light optical microscope (LOM) were used to characterise the oxides.     

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.     

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.     

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.     

不锈钢中15个元素的ED—XRF分析

不锈钢是应用十分广泛的合金钢,成份的含量对性能有重要影响,湿式化学法材料消耗多,慢,采用ED—XRF同时分析其中15个元素,速度快,效率高,能满足分析要求。     

A new high temperature life correlation model for austenitic and ferritic stainless steels

Low-cycle fatigue tests on 429EM ferritic stainless steel and 316L austenitic stainless steel were carried out in a wide range of temperatures from room temperature to 750 °C. The Tomkins fatigue life model was applied to correlate the fatigue life with crack propagation rate and this model matched well with the fatigue life of 429EM stainless steel but not for the 316L stainless steel. A new life prediction model was developed to consider the temperature effect on fatigue life. The predictions show good agreement with experimental results for both materials. The predicted lives were within a±2X scatter band at all test temperatures.     

含不锈钢纤维机织物电磁屏蔽机理及其效能的仿真研究

依照电磁屏蔽理论,介绍了金属织物电磁屏蔽的机理。在此基础上,利用多物理场耦合分析软件COMSOL Multiphysics,建立三维仿真模型,分析了不同电磁波极化方向、不同半径和不同嵌织间距的奥氏体304不锈钢长丝,在不同辐射频率下对织物屏蔽效能的影响。仿真结果表明,极化方向、半径大小、嵌织间距和频率,对屏蔽织物都有显著的影响,这对不锈钢长丝防电磁辐射织物的开发和设计提供理论依据。     

超低碳含铜铸造不锈钢的组织与腐蚀行为

采用金相显微镜、Ｘ射线衍射、透射电镜、电子探针显微分析手段和多种腐蚀试验方法研究了超低碳含铜铸造不锈钢的析出相种类、成分、结构、形貌、分布及其腐蚀行为。结果表明，含Ｃｕ为２．０％的００Ｃｒ２０Ｎｉ２５Ｍｏ５钢经１１５０℃固溶处理可得到单相奥氏体组织，并具有优良的耐全面腐蚀、晶间腐蚀、点蚀和电化学腐蚀性能。     

Prodigy DC Arc直流电弧光谱法测定纯钽及钽制品中铁元素

试验探讨了DC Arc直流电弧光谱仪测定纯钽及钽制品中Fe元素的条件,并建立了测定方法。通过试验确定了Fe元素的分析线波长、积分时间及背景点位置。按照实验方法测得样品中Fe元素的加标回收率在92.73%—107.27%之间,含量测定的相对标准偏差(RSD,n=10)为4.8%,Fe元素的检出限为1.41μg/g。本法对标准样品的测定结果与GE-340光栅光谱法、DV-5直流电弧光谱法的测定结果基本一致。     

The specific cost of the surface grinding of vanadium high-speed steel with superabrasive wheels

The processes of grinding the R6M5F3-grade steel with kubonit and diamond wheels dressed by the electroerosion method have been compared using a criterion for a minimum unitary grinding cost. It has been shown that the unitary grinding costs for wheels being compared are practically equal, which gives the possibility to equally use wheels of the compared superabrasives in grinding the R6M5F3 steel.     

钛和18/8不锈钢冶金结合层的研究

用金相、显微硬度,扫描电镜、X 射线能谱及 X 射线衍射等方法研究了钛和18/8不锈钢之间的扩散结合层和爆炸结合层。确定了结合层中各相的成份和晶体结构。扩散结合层中分为六层,它们是靠近不锈钢侧的α—Fe、Fe_(35)、Cr_(13)、Ni_3、Ti_7和 Ti(Fe_(0.75)Cr_(0.15)Ni_(0.1))_2三层和靠近Ti 侧的β一Ti 和含有 Fe、Cr、Ni 的α—Ti 两层,在这之间是一层液相凝固层,其中又有 Ti(Fe_(0.81)Cr_(0.13)Ni_(0.06))和β一Ti 两相。爆炸焊熔区的成份大约相当于钛与不锈钢以1∶1混合而成,其中主要的相是 Ti(Fe_(0.75)Cr_(0.15)Ni_(0.1))_2。本文并讨论了各相层的形成规律。     

Zn-Se/不锈钢薄膜的电沉积及其应用研究

研究了Zn-Se/不锈钢薄膜的电沉积工艺条件及其在染料废水处理中的应用.讨论了电流密度、初始浓度比(c(ZnSO4):c(Na2SeO2))、pH值、柠檬酸钠加入量、电沉积时间、电沉积温度以及超声功率对镀层的影响.经扫描电镜及能谱仪分析测试表明,在电流密度为3.8mA/cm2、初始浓度比为250:1、pH=2.9、柠檬酸钠加入量为14.71g、电沉积时间为7min、电沉积温度为55℃、超声功率为160W条件下制备出的Zn-Se/不锈钢薄膜,其表面结晶致密、均匀,Zn与se的化学计量比为1:1.25.用所制备的薄膜材料作阴极,采用电化学复合技术处理罗丹明B模拟染料废水,可使模拟废水的脱色率接近99%,COD去除率接近90%.     

316L/S32101异种金属焊接接头的显微组织与力学性能研究

目的 研究乏燃料水池用钢板316L与覆板S32101双相不锈钢的焊接性、接头不同区域显微组织特征及接头与母材之间的性能差异.方法 利用氩弧焊接技术对5 mm厚的316L底板与3 mm厚的S32101覆板以搭接的形式进行焊接,利用金相显微镜、扫描电镜、维氏显微硬度仪和电子万能材料试验机对焊接接头的宏观形貌、显微组织以及力学性能进行研究.结果 316L/S32101焊缝组织主要由铁素体基体、晶界树枝状奥氏体以及晶内细小片状奥氏体所组成;316L侧靠近焊缝处存在一个较窄的熔合区,其组织由奥氏体基体和少许细小分散的铁素体组成,而S32101侧靠近焊缝处组织则由粗大铁素体晶粒和沿晶粒边界分布的若干小块状奥氏体组成.从316L母材区到焊缝区,硬度显著增大,而从焊缝区到S32101母材区,硬度变化很小;焊接接头的抗拉强度高达510 MPa,为两侧316L和S32101母材强度的87.9％和88.6％.结论 在焊接电流为240 A和焊接速度为300 mm/min的条件下,可以通过氩弧焊获得成形良好的搭接接头,且接头的力学性能优异.