罩式炉退火对430系不锈钢表面质量的影响

 研究了罩式炉退火对430系不锈钢表面氧化铁皮结构变化的影响,并对这种变化在后续冷轧工序中造成的质量问题进行了分析。首次对长期存在的“退火印”缺陷做出了完整的理论解释,并根据现场工艺试验结果,提出了解决方案。     

氢致奥氏体不锈钢晶格畸变

对304L和316L奥氏体不锈钢试样在充氢后和充氢同时进行X射线衍射分析,观察到在充氢过程中存在奥氏体晶格膨胀-收缩-膨胀的现象;在充氢后时效一段时间的情况下,存在奥氏体晶格收缩-膨胀-收缩的现象,并初步讨论了可能的原因。     

提高铁素体不锈钢质量的主要措施

介绍了易于在铁素体不锈钢中出现的主要缺陷,包括室温敏感性高和起皱。总结了改善铁素体不锈钢质量的主要措施。     

Mechanisms of Hydrogen Induced Stress Crack Initiation and Propagation in Super Duplex Stainless Steels

Austenitic and ferritic duplex stainless steels, DSS, have recently suffered from hydrogen stress induced cracking, HISC, in subsea components with a cathodic protection. This paper provides discussions on possible HISC mechanisms. HISC initiation can occur at the ferritic grain boundaries and phase boundaries at a stress lower than the yield strength, but dominantly at phase boundaries at a stress higher than the yield strength. EBSD analysis shows that HISC in DSS results from the interaction between the dynamic plasticity by creep and hydrogen diffusion. A model on the formation of microstresses in these two phases under creep conditions is proposed, which explains why HISC occurs mainly in the ferritic phase. Discontinuous two‐dimensional HISC paths were observed. The austenitic phase acts as obstacles for crack propagation. The fracture covers “valleys” and “peaks” with the cleavage ferrite and the austenite with microfacets or striations due to the hydrogen‐enhanced localized‐plasticity.     

IF钢再结晶退火过程中析出相行为研究

对IF钢在退火过程中二相粒子的演变规律进行了研究,结果表明:退火以前形成的二相粒子,如TiC,在经过罩式退火和连续退火后,其尺寸、形状和分布有较大的区别;在连续退火中不形成新的析出相,而在罩式退火中形成两类新的析出相-FeTiP相和(Ti,Mn)S相。这是首次报道有关FeTiP相在含P,Mn较低(P ≤ 0.01%,Mn<0.2%)的IF钢中析出,以及Mn以(Ti,Mn)S相的形式在罩式退火中析出。还着重研究了这2种新相的粒度、分布、相结构以及析出机制,并探讨了它们对IF钢大生产的意义。     

Effect of Microstructure and Surficial Oxidation on the Wear Behavior of an UNS S41003 Stainless Steel

The UNS S41003 ferritic stainless steel is a low-carbon alloy that has great corrosion and oxidation performances in wet and aqueous environments, as well as it has high mechanical strength and ductility when compared to the most ordinary low-carbon steels. These great characteristics, allied to its relatively low manufacturing cost, have made it a potential option to replace structural steels in many applications. Although it is a current trend, there are still few published studies that relate this steel manufacturing process with microstructural evolution and mechanical behavior, mainly regarding its wear behavior, which is a substantial and sometimes limiting characteristic for its applications. In this context, this article presents a pioneering study about the use of biphasic microstructures (ferrite–martensite) and controlled surficial oxidation to enrich the wear behavior of a UNS S41003 steel type. This study concludes that, if well planned, both the increase of martensite fraction and the controlled growth of an adherent and compact oxide layer on the steel surface significantly improve its wear performance, decreasing its wear rate up to 93%.     

国产不锈钢全氢罩式退火炉的关键技术及实现

将自主开发的关键设备和成套控制系统与软件应用到国产不锈钢全氢强对流罩式退火炉机组,考虑到不锈钢退火炉温度高的特点,对罩式炉关键部分进行了优化设计,同时采用了国产的关键零部件。实践表明,不锈钢罩式退火炉运行安全可靠,各项技术指标均达到设计要求。     

奥氏体不锈钢应力腐蚀断裂诊断专家系统案例库

在收集400多个奥氏体不锈钢应力腐蚀失效的典型断裂事故案例的基础上,建立了应力腐蚀断裂诊断专家系统(Estar-1系统)的案例库,并从这些案例中提取相应的应力腐蚀断裂的经验规则,进行推理设计,运用这个案例库不仅能对奥氏体不锈钢应力腐蚀断裂失效进行辅助诊断,而且能提出相应的防护措施。     

304奥氏体不锈钢高温氧化行为研究

针对304热轧卷高温氧化缺陷问题,通过SEM,EPMA,XRD,EDS和XPS分析了304热轧卷氧化皮的成分和结构,研究了304的氧化行为,探讨了大生产过程中卷取温度对304氧化行为的影响.研究表明304奥氏体不锈钢热轧卷的氧化皮结构比较致密,主要成分为铁铬尖晶石(Fe3-yCryO4).304的抗氧化性较强,温度低于900℃时,氧化极为缓慢;温度高于900℃后,氧化稳步增加.适当降低卷取温度,有利于304氧化皮的去除.     

冷轧不锈钢连续退火在线检测

为快速反馈不锈钢带退火质量,减少退火工艺调整时间,降低取样费用,根据奥氏体不锈钢和铁素体不锈钢的特点,用超声波和剩磁法在线检测退火后晶粒尺寸,有效控制连续退火酸洗线带钢退火性能,目前已在国内外多条冷轧不锈钢连续退火酸洗线上得到了成功应用。     

Influence of Laves Phase Precipitation and Coarsening on High‐Temperature Strength of Ferritic Stainless Steels

Downsizing trends in the design of internal combustion engines require ferritic steels with greater strength at elevated temperatures. One method of improving the high‐temperature strength is precipitation hardening with intermetallic phases such as the Laves phase. Thermodynamic calculations show, that the elements Nb and Si contribute to the Laves phase formation strongly. In this work, the influence of intermetallic precipitates on the mechanical properties of three different ferritic Fe? Cr stainless steels was investigated and compared to a reference material. The three main hardening mechanisms – precipitation–hardening, grain refinement, and solid‐solution strengthening – were studied with appropriate alloy compositions and thermo mechanical treatment. Investigations were performed with uniaxial compression tests of samples aged isothermally at 900°C for up to 1440 h. It is shown that, the solid solution effect of Mo and W increases the high‐temperature strength about 40%, also after long‐term annealing. The contribution of the Laves phase precipitates on the high‐temperature strength is rather small due to their rapid coarsening.