双相不锈钢热塑性的研究

本文采用落锤试验法，研究了在不同试验温度下镍、氮合金元素含量和α／γ两相比例对高铬镍双相不锈钢热塑性的影响。     

双相不锈钢的开发和应用现状

本文综述了双相不锈钢的开发和应用现状。介绍了新发展的含氮双相不锈钢和粉末冶金双相不锈钢,还叙述了双相不锈钢在改善热加工性方面,以及晶粒细化和超塑性化等方面的概况。     

On Phase Equilibria in Duplex Stainless Steels

The equilibrium conditions of four duplex stainless steels; Fe‐23Cr‐4.5Ni‐0.1N, Fe‐22Cr‐5.5Ni‐3Mo‐0.17N, Fe‐25Cr‐7Ni‐4Mo‐0.27N and Fe‐25Cr‐7Ni‐4Mo‐1W‐1.5Cu‐0.27N were studied in the temperature region from 700 to 1000 °C. Phase compositions were determined with SEM EDS and the phase fractions using image analysis on backscattered SEM images. The results showed that below 1000 °C the steels develop an inverse duplex structure with austenite and sigma phase, of which the former is the matrix phase. With decreasing temperature, the microstructure will be more and more complex and finely dispersed. The ferrite is, for the higher alloyed steels, only stable above 1000 °C and at lower temperatures disappears in favour of intermetallic phases. The major intermetallic phase is sigma phase with small amounts of chi phase, the latter primarily in high Mo and W grades. Nitrides, not a focus in this investigation, were present as rounded particles and acicular precipitates at lower temperatures. The results were compared to theoretical predictions using the TCFE5 and TCFE6 databases.     

电站锅炉用 TP347H 不锈钢无缝管工艺的开发

太钢采用铁水预处理+30 t电弧炉熔化合金钢水-75 t K-OBM-S吹炼-VOD处理-LF精炼-5．6 t铸锭开坯(或220 mm×220 mm铸坯)-Φ100 mm管坯穿孔-冷轧(冷拔)流程,生产了Φ38 mm×6．6 mm TP347H (1Cr19Ni11Nb)钢无缝管。结果表明,通过控制[O]≤30×10^-6、[H]≤3×10^-6、As≤0.003 0％、Pb、Sn、Sb、Bi分别≤0．001 0％以及钢中C含量0.06％～0.08％、Nb含量0．6％-0.8％,钢管具有优良的冷、热加工性能,其各项性能均满足ASME和GB标准的使用要求。     

超塑性奥氏体-铁素体双相不锈钢00Cr25Ni7Mo3N的研制

通过电弧炉-电渣重熔工艺开发研制了成分为(%):0.021C,24.16Cr,7.21Ni,2.87Mo,0.17N,0.48Cu超塑性双相不锈钢00Cr25Ni7Mo3N。试验结果表明,00Cr25Ni7Mo3N超塑性双相不锈钢的耐孔蚀性和耐缝隙腐蚀性远高于传统的304L和316L奥氏体不锈钢。在变形温度960℃、应变速率2×10^-3/s时,00Cr25Ni7Mo3N超塑性双相不锈钢的最高延伸率为960%,该钢超塑性变形的均匀性优于TC4钛合金,可显著减轻构件的重量。     

不锈钢冶炼设备和工艺路线

通过对不锈钢主要冶炼设备———初炼炉、精炼炉、真空吹氧装置的分析以及一步法、二步法、三步法不锈钢工艺路线的比较 ,提出应根据不锈钢的生产规模、产品大纲、原料供应、现有车间条件和动力供应状况 ,合理选择相应的主要冶炼设备和工艺路线 ,以便达到最佳的经济、技术效果。文中列出不锈钢冶炼设备和工艺路线选择一览表。     

S31803 双相不锈钢酸洗工艺的试验

S31803奥氏体-铁素体双相不锈钢(%:0.03C、22.05Cr、5.23Ni、3.10Mo、0.16N)合金含量高,氧化层中所含的合金元素多,氧化物结构复杂,不易酸洗.通过正交试验得出H2SO4 220 g/L,NaCl 30g/L,添加剂10 g/L,在60℃平均酸洗时间57.2 min,使酸洗后的钢板表面色泽均匀,酸洗合格率达100%.     

焊接用双相不锈钢ER2209线材的生产实践

通过对焊接用双相不锈钢ER2209线材生产实践过程中的冶炼、轧制、固溶及酸洗工艺的研究,结果表明：最佳的热加工温度为1000～1050℃,可有效避免σ相析出导致的轧制开裂;热处理温度为1050～1100℃,材料的强度较低,塑性较高,冷拉拔性能优异;采用(H₂SO₄+HF)溶液预处理及(HNO₃+HF)混酸洗的工艺进行酸洗,线材表面质量优异,无酸洗晶间腐蚀。     

Duplex Stainless Steels ‐ a Review after DSS ‘07 held in Grado

Duplex stainless have always been an exiting area of interest for researchers, stainless steel producers, fabricators and end users. They present very diversified technical challenges and simultaneously attractive in‐service properties at excellent cost/properties ratios, particularly in critical markets including oil and gas, chemical industry, pulp and paper industry, water systems, desalination plants, pollution control equipments, chemical tankers, etc. This explains why although they still remain a marginal production in the stainless steel business (less than 1%) dedicated international conferences have been organised since about 25 years. The purpose of this paper is to present a review of the 100 scientific contributions presented during the latest international duplex stainless steel conference witch took place in Grado, Italy, on 18‐20 June 2007. The main topics concerned microstructure and mechanical properties, weldability, corrosion resistance and in‐service properties. The “standard” duplex stainless steels, i.e. the 2304, 2205, and the family of 2507 (Cu,W, ...) grades were confirmed as very valuable grades with outstanding performances proven in more than 20 years successful in‐service applications. New grades including the so‐called lean duplex dedicated to volume oriented markets (possible replacement of 304/316 grades) and some “niche” grades dedicated to very specific markets were presented. It was pointed out that the duplex grades start to be well established products particularly suitable for corrosion resistance applications. They show a two‐digit yearly growth thanks to the production of new grades and production ranges (coils and bars) targeting the replacement of the more costly 300 series including 304 but also rusty carbon steel in e.g. structural application.     

2507超级双相不锈钢的热变形行为

用MMS-200热模拟实验机对2507超级双相不锈钢(/%:0.022C、0.58Si、25.35Cr、7.17Ni、4.05Mo、0.28N)12 mm热轧板在1 000～1150℃、应变速率0.01～10s^-1下进行了热压缩实验。实验结果表明,在应变速率一定的条件下,变形温度越高,2507超级双相不锈钢峰值应力越低;在变形温度一定的条件下,峰值应力随着应变速率的增加而增加。根据热变形方程计算得到压缩变形时的平均表观应力指数n=3.25,热变形激活能Q=460kJ/mol。基于实验数据构建了2507超级双相不锈钢在相应变形条件下的热变形方程。     

热卷箱在2250热连轧不锈钢带生产中的应用

热卷箱是置于热连轧钢带生产线上粗轧机与精轧机之间,将中间坯卷取和开卷的一种设备。通过设备和工艺攻关,太钢2250热连轧生产线成功地应用热卷箱规模化生产热轧2～5.2 mm 300系和400系不锈钢带,提高了钢带的表面质量和生产效率。文中探讨了热卷箱应用于不锈钢带生产的优劣势和生产中易出现的划伤和花印等问题。     

近终形连铸在不锈钢生产中的应用

目前全世界已投产、在建和计划建设的薄板坯连铸生产设备达５２套，其中主要用于或一部分用于生产不锈钢的设备有６套。