奥氏体不锈钢保护渣的研制

针对奥氏体不锈钢成分的特殊性及可能产生的夹杂物,提出了连铸保护渣的相应研制思路,以此开发的保护渣在宝钢集团浦钢公司进行了数十炉的工业试验。结果证明,研制的奥氏体连铸保护渣各项性能均取得了较为满意的结果,铸坯质量及轧制性能达到了用户要求。     

粉末锻造制备含氮奥氏体不锈钢

介绍粉末包套烧结-自由锻造法制备含氮钢的过程。它包括含氮粉末准备→装粉→烧结→包套焊封→自由锻造等技术措施。本工艺比较简单，易于操作，对相应设备要求低。通过本技术制备的含氮奥氏体不锈钢材料相对密度达99％以上，且氮含量能满足含氮钢要求，其拉伸性能与粉末注射成形、高压熔炼等工艺制得的含氮奥氏体材料相当。     

Development and application of nitrogen-alloyed austenitic stainless steels in Baosteel

In recent years,nitrogen-alloyed stainless steels have been a research hotspot in the field of stainless steel product and technology. Nitrogen-alloyed austenitic stainless steels developed by Baosteel and their applications are introduced. These steels are nitrogen-controlled products 304 N and 316 LN,nitrogen containing economical products BN series and high-nitrogen stainless steel( HNS) series. The results show that the presence of nitrogen can significantly improve the strength and corrosion resistance of steel produced. By nitrogen alloying,economical austenitic stainless steels w ith considerably less nickel than 304 can be obtained; the corrosion resistances of these steels are almost the same as 304. Furthermore,by a scientific approach of nitrogen alloying,high-nitrogen steel of0. 8% nitrogen content is fabricated under the non-pressurized conditions,and the pitting potential of this steel is 1. 0 V. At present,nitrogen-alloyed steels developed by Baosteel are w idely utilized in the manufacture of cryogenic storage containers,transportation containers,and many household w ares.     

Use of elastic constants based on ab initio computation in materials optimisation of austenitic stainless steels

The use of ab initio quantum mechanics methods to compute elastic constants of austenitic stainless steels is reviewed. It is demonstrated that the elastic constants can be predicted accurately as a function of composition. This enables the use of materials optimisation techniques to develop new materials that are systematically adapted to specific components. After the design criteria and the target function to be optimised have been formulated, the optimum property combination can be searched for. The properties involved constitute a property space, where domains with active design criteria are identified. In the present paper, the domain where the stiffness is the controlling property is considered. Cost, weight and environmental impact minimisation is analysed. It turns out that for all three target functions, austenitic stainless steels with low chromium and nickel contents are preferred materials.

On examine l’utilisation des méthodes de mécanique quantique ab initio pour le calcul des constantes d’élasticité des aciers inoxydables austénitiques. On démontre que l’on peut prédire avec précision la constante d’élasticité en fonction de la composition. Ceci rend possible l’utilisation des techniques d’optimisation des matériaux dans le développement de nouveaux matériaux qui sont adaptés systématiquement à des composantes spécifiques. Après l’identification des critères de conception et de la fonction cible à optimiser, on peut chercher la combinaison optimale de propriétés. Les propriétés impliquées constituent un espace de propriété, où l’on identifie les domaines avec critères de conception actifs. Dans cet article, on considère le domaine où la rigidité est la propriété de contrôle. On analyse la minimisation du coût, du poids et de l’impact environnemental. En fin de compte, il se trouve que pour les trois fonctions cible, les aciers inoxydables austénitiques à faible teneur en chrome et en nickel sont les matériaux préférés.     

Recent developments in stainless steels:austenitic,ferritic,duplex

A review is given concerning some of the recent industrial developments of stainless steels. In austenitic stainless steels,two different directions of alloy development are noticeable:low nickel austenitic stainless steels and high nitrogen stainless steels.In these two cases the aims are different,particularly in terms of strength,but the philosophy of alloy development and the scientific approaches are very similar and they all revolve about the role of nitrogen as an alloying element and how this affects strength,ductility and corrosion resistance. There is now a broad and useful basis of information as to how nitrogen affects solid solution hardening,grain boundary hardening and work hardening and how to make use of these effects in developing materials required by the world market. In the field of corrosion resistance,ferritic,duplex and austenitic stainless steels compete with each other and now there is a growing body of information concerning the relative corrosion resistance based on laboratory data. However,for practical applications and for alloy selection,more than just laboratory data are needed,and thus,the first results are presented here of a many years comparison of the corrosion resistance of 24 commercial stainless steels exposed to corrosion in outdoors marine atmosphere.Hope is expressed to involve in the near future even more steels from a wider range of manufacturers in such corrosion studies.This might help consumers in appropriate alloy selection.It might also help steel makers in developing appropriate stainless steel grades.     

Effect of strain-induced martensitic phase transformation on the formability of nitrogen-alloyed metastable austenitic stainless steels

Strain-induced martensitic phase transformation and its influence on the formability of newly developed nitrogen-alloyed metastable austenitic stainless steels were systematically investigated. Yield strength for the asreceived steels bearing lownickel content was around 300 MPa and their elongation ratios varied from 55. 2% to61. 7%. Erichsen numbers of these samples differed from 13. 82 to 14. 57 mm. Although its Cu content was lower than that of other samples,steel D2 exhibited better plasticity and formability,which was attributed to γ→α'martensitic phase transformation. EBSD,XRD,and magnetism tests showed that increases in deformation ratio gradually increased the α' martensite phase of a sample,thereby contributing to its strain and inducing the optimal transformation-induced plasticity effect. An M_(d30/50) temperature of around 20 ℃,which is close to the deformation temperature,provided the austenite with adequate stability and gradually transformed it into martensite,thereby endowing lean ASS with better formability.     

铸造奥氏体不锈钢的疲劳裂纹扩展

用紧凑拉伸试样研究了载荷比、单峰过载和两步高-低幅加载对Z3CN20-09M铸造奥氏体不锈钢疲劳裂纹扩展速率的影响.当应力强度因子范围相同时,疲劳裂纹扩展速率随载荷比的增大而增大.单峰过载使裂纹扩展速率先有短暂的增加后长距离的减速扩展,出现裂纹扩展迟滞现象.两步高-低幅加载时,若两步的最大载荷不同,第二步裂纹扩展也会出现迟滞现象.用两参数模型和Wheeler模型能够预测恒幅载荷和变幅载荷下的疲劳裂纹扩展行为.     

奥氏体耐热不锈钢的焊接实践

通过对奥氏体耐热不锈钢的焊接性分析，提出奥氏体耐热不锈钢焊接应采取的焊接工艺及应注意的问题．     

晶粒细化对奥氏体不锈钢高温力学性能的影响

摘要：对粗晶201LN奥氏体不锈钢采用60%冷变形结合700℃退火120s工艺制备超细晶奥氏体不锈钢,研究晶粒细化对奥氏体不锈钢高温力学性能的影响。利用光学显微镜、扫描电子显微镜、透射电子显微镜、电子背散射衍射技术对粗晶和超细晶奥氏体钢进行了组织表征,并使用万能试验机测试20和650℃环境下力学性能。结果显示粗晶奥氏体不锈钢经过冷变形结合退火工艺处理,平均晶粒尺寸由18μm细化为0.9μm,屈服强度由383MPa提高到704MPa,而伸长率由63.8%下降到46.3%,表明晶粒细化能有效提高奥氏体不锈钢屈服强度的同时较小损害塑性,TEM证实其形变机制均为形变诱导马氏体和孪生协同作用。当温度由20℃提高到650℃时,粗晶奥氏体不锈钢屈服强度和伸长率分别下降到180MPa和28.1%,超细晶奥氏体不锈钢屈服强度和伸长率分别为384MPa和24.2%。这表明在650℃高温环境下细晶强化作用仍然有效,粗晶和超细晶奥氏体不锈钢也有较好的塑性,其形变机制分别变为位错滑移和位错滑移+层错+孪生。     

高氮奥氏体不锈钢强韧化及抗弹性能研究进展

高氮奥氏体不锈钢(high nitrogen austenitic stainless steel,HNASS)是一种目前正在蓬勃发展的新型不锈钢,被广泛运用到交通运输、海洋工程、建筑材料、医疗器材和军事工业等领域.节镍高氮的奥氏体不锈钢相比于传统奥氏体不锈钢,其具有优良的综合力学性能,如高强度、高韧性、大的蠕变抗力、...     

粉末注射成形奥氏体不锈钢的疲劳和冲击强度

本文的目的是研究粉末性能对粉末注射成形奥氏体不锈钢的力学性能(特别是疲劳和冲击强度)的影响。试样用混有聚酰氨粘结剂系的水雾化(WA)和气雾化(GA)粉末制成。注射坯在空气中脱粘，而后在不同温度、不同保温时间下真空烧结。粉末性能对烧结体的密度、显微组织和力学性能有显著影响。孔和析出物显示出Ostward时效，而孔和析出物的长大满足Lifshitz-Wagner方程。WA和GA粉末试样的疲劳极限分别约为300MPa和310MPa。它们的疲劳强度略低于常规锻材。烧结体的冲击值随密度增加线性增大。     

不锈钢生产现状及广钢开发不锈钢的探讨

分析国内外不锈钢的生产现状和消费情况及广东省对不锈钢的需求，并对广钢集团介入不锈钢的生产提出了建议；最后就珠钢续建工程生产不锈钢的生产规模、生产品种、装备配置提出了初步设想。     

奥氏体不锈钢中硫含量的研究

通过对不同硫含量铸坯和成品硫化物夹杂大小以及等级进行分析,研究了奥氏体不锈钢中硫含量对性能的影响。结果表明,随着硫含量的增加,不锈钢铸坯和成品中最大夹杂物尺寸逐步增加,成品夹杂物等级也相应提高,当硫的质量分数不大于21×10~(-6)时,成品硫化物夹杂低于最小评级要求;奥氏体不锈钢冲击性能与硫含量呈反比例关系,当硫的质量分数高于75×10~(-6)时,可能导致304不锈钢脆断。     

Cr-Mn-N奥氏体不锈钢的晶间腐蚀性能研究

晶间腐蚀性能是钻铤结构件用奥氏体无磁不锈钢的重要性能之一.采用不锈钢10％草酸浸蚀试验方法、不锈钢65％硝酸腐蚀试验方法以及不锈钢硫酸-硫酸铜试验方法对三种不同成分的Cr - Mn -N奥氏体不锈钢做了晶间腐蚀试验.试验结果表明,A钢种在不同的腐蚀条件下均具有良好的耐晶间腐蚀性能,该材料按0.03％C、18.96％ Cr、0.57％N的化学成分设计可以达到优良的耐晶间腐蚀性能.     

固溶时效后高氮奥氏体不锈钢的物理化学相分析

采用物理化学相分析技术研究了高氮奥氏体不锈钢固溶时效后的碳、氮化物析出行为,确定了析出相的类型、粒度分布、含量及组成结构式.结果表明:氮含量低的1Cr22Mn15N0.6以M₂₃C₆型碳化物析出为主,氮含量高的1Cr22Mn15N0.9以(CrFe)₂N_1-x型氮化物析出为主,高氮奥氏体不锈钢中析出物的总量随时效时间的延长而增加.     

409L和430铁素体不锈钢耐局部腐蚀性能

采用电化学测试技术与化学浸泡实验相结合,对比研究了409L和430铁素体不锈钢热轧板材耐点蚀和耐晶间腐蚀的能力.结果表明:409L不锈钢的击穿电位与保护电位的差小、钝化膜的修复能力较强,表现为小尺度的浅点蚀孔;430不锈钢的击穿电位较高,耐点蚀能力高于409L不锈钢,但430不锈钢热轧态的条带组织有明显的腐蚀微电池效应,表现为比较严重的全面腐蚀;409L不锈钢含Cr量低,且其热轧态未经过稳定化处理,使得409L不锈钢耐晶间腐蚀能力劣于430不锈钢.经微观分析:409L不锈钢为沿着基体等轴晶界的典型晶间腐蚀形貌特征,而430不锈钢在轧向碳化物(M₂₃C₆)与基体的相界面上呈现分层腐蚀痕迹.     

Structure and properties of powder austenitic die steels

Possibilities are considered for using powder metallurgy in order to prepare effective austenitic die steels exhibiting high hardness and heat resistance (at temperatures not less than 850 °C). It is shown that in strength properties the material developed are as good as the best austenitic steels used as die tools, and in the level of heat resistance and hardness at room temperature they a considerably better. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(450), pp. 26–30, July–August, 2006.     

Development of high strength ferrite-martensite stainless steels (FMSSs) for railway cargo transportation

Two ferrite-martensite stainless steels(FMSSs)were developed by Baosteel based on the T4003 composition,through optimizing the manganese and nickel contents,reducing silicon,carbon and nitrogen contents,controlling remnant niobium and molybdenum,adding sufficient titanium and controlling the processing.In this study,the physical metallurgy of such FMSSs was investigated with the emphasis on the alloying effect on the phase balance during processing and the transformation behavior during welding for different microstructures.In addition,the mechanical behavior and the weldability were investigated.The results indicate that such steels have a good combination of strength and toughness and better weldability compared with the traditional 1.4003 steel.Such high strength steels are highly suitable for railway cargo transportation where the wall thickness of the wagons can be reduced,resulting in weight savings.     

改进310奥氏体不锈钢长期时效后的组织与性能

借助扫描电子显微镜、透射电子显微镜以及高温、室温拉伸和硬度测试研究了实验室研发的改进310奥氏体不锈钢在700℃长期时效后的组织与性能.700℃时效1000 h后,实验钢在晶界和晶内析出了大量(Cr,Fe,Mo)₂₃C₆、(Cr,Fe)₂₃C₆、σ相和少量的χ相.析出相对实验钢的室温力学性能有明显的强化作用.强度增加,硬度升高20 Hv,同时延伸率仍保持在30%以上.高温下,析出强化效应减弱,延伸率轻微下降.通过断口表面和剖面观察发现,时效1000 h后,实验钢的高温拉伸断口为韧性断裂,未观察到裂纹和孔洞;而室温拉伸断口为脆性断裂,断口附近则观察到σ相中出现裂纹和孔洞.从σ相的脆-韧转变和实验钢基体的室温和高温强度的不同,讨论了在室温拉伸过程中产生裂纹和孔洞的原因,以及时效对室温和高温力学行为的不同影响.     

Precipitation of carbide and its effects on the properties of nickel-saving austenitic stainless steel

In this work,the effects of temperature and cooling rate on the precipitation of carbides in nickel-saving metastable austenitic stainless steel were studied.The test results show that the temperature range of carbide precipitation in the test steel was 500-950℃,and 750℃was the most sensitive temperature.However,when completely solution treated samples were cooled from high to room temperature at a cooling rate of more than 50 K/s,no carbides precipitated.The carbide precipitates increased the yield strength but decreased the corrosion resistance of the steel,with little impact on toughness.