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.     

奥氏体不锈钢压力容器焊接裂纹的产生原因及其预防

分析奥氏体不锈钢压力容器在焊接过程中所产生的裂纹性质、形成机理,以及材料的化学成分和工艺措施对裂纹产生的影响,指出产生热裂纹的主要原因;采取了控制材料的化学成分和合理的焊接工艺等措施,以防止热裂纹的产生。     

节镍型奥氏体不锈钢J5裂纹缺陷控制措施

节镍型奥氏体不锈钢是一种以氮代镍来获得稳定奥氏体组织的新钢种,它不仅可以节约镍资源,还可以提高不锈钢的综合性能,其应用范围广泛,主要用于制管、建筑装饰等行业。然而近年来随着应用范围的扩大,对其质量的要求越来越高,铸坯的裂纹问题更显突出,对下游工序的轧制造成了一定影响,同时对质量也产生较严重的影响。文章通过现场实践分析节镍型奥氏体不锈钢的裂纹缺陷原因,并针对性地采取对应措施,满足公司的质量要求和合同要求。     

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。     

深冲用0Crl8Ni9Cu2奥氏体不锈钢冷轧板成形性试验研究

通过单轴拉伸试验求得的应变硬化指数n值和塑性应变比r值，是当今世界公认的用来评定金属薄板成形性优劣的重要参数。本文通过对太钢新开发的深冲用0Crl8Ni9Cu2奥氏体不锈钢冷轧板进行成形性试验研究，探讨了其成形性的优劣并提出了改进措施。     

铬锰氮奥氏体不锈钢热轧钢带横裂纹分析

201Cu是在传统铬锰氮奥氏体节镍不锈钢201的基础上添加一定含量的铜元素而形成的不锈钢，与201相比具有硬度低、塑性和深冲性能好的特点，深得不锈钢制品行业的青睐。但今年4月我公司部分201Cu不锈钢连铸小板坯在轧制成钢带后，固溶酸洗后的No．1钢带卷上出现横裂纹。给生产造成了较大的影响，经过对201Cu进行残余元素分析、缺陷部位金相分析和扫描电镜能谱分析，     

TS21不锈钢板坯纵向凹陷裂纹分析及工艺改进

采用国产不锈钢板坯连铸机生产TS21不锈钢,板坯存在纵向凹陷以及微裂纹缺陷,在分析其产生原因的基础上,提出增大保护渣的粘度、熔点和二元碱度及优化浸入式水口尺寸及水口插入深度等改进措施,通过试验并在生产中应用,效果明显。     

奥氏体不锈钢半成品钢板表面缺陷成因分析

1Cr18Ni9Ti半成品钢板表面常出现“花斑”状缺陷，严重影响了不锈钢中板的表面质量。研究表明：该缺陷宏观上表现为局部重皮状折叠的特征；微观上伴随有α相的数量及分布在缺陷与非缺陷表面显著不同的特点。因此认为“花斑”实质上是一种不均匀变形引起的表层局部折叠；α相的不均匀分布为这类缺陷的产生提供了可能。     

304奥氏体不锈钢带氧化铁皮直接冷轧技术的研究

结合现场生产实际,通过在试验室对奥氏体不锈钢304黑皮卷直接进行压下率分别为10%,20%,30%的冷轧然后退火酸洗的试验,证明在退火酸洗工艺相同的情况下,通过在热轧后进行一定压下率的直接轧制,可以获得与传统No.1产品相比晶粒尺寸等级相同、表面粗糙度更低、力学性能和耐蚀性相近的2E产品,并且获得更大的热轧产品厚度范围,降低冷轧一个轧程后的产品厚度.因此根据不同客户的要求,可以用2E产品替代No.1产品.     

精密不锈钢带冷轧生产工艺

介绍了精密不锈钢带的生产工艺,并对森吉米尔20辊轧机的某些先进技术作了详细的描述,指出精密不锈钢带冷轧生产工艺是目前较为先进的一项冷轧技术。     

Metallurgical Studies of Austenitic Stainless Steel 304 under Warm Deep Drawing

Austenitic stainless steel 304 was deep drawn with different blank diameters under warm conditions using 20 t hydraulic press. A number of deep drawing experiments both at room temperature and at 150 ℃ were conducted to study the metallography. Also, tensile test experiments were conducted on a universal testing machine up to 700 ℃ and the broken specimens were used to study the fractography of the material using scanning electron microscopy in various regions. The microstructure changes were observed at limiting draw ratio （LDR） when the cup is drawn at different temperatures. In austenitic stainless steel, martensite formation takes place that is not only affected by temperature, hut also influenced by the rate at which the material is deformed. In austenitic stainless steel 304, dynamic strain regime appears above 300 ℃ and it decreases the formability of material due to brittle fracture as studied in its fractography. From the metallographic studies, the maximum LDR of the material is observed at 150 ℃ before dynamic strain regime. It is also observed that at 150 ℃, grains are coarse in the drawn cups at LDR.     

New Stainless Steel Solutions as Economic Alternatives to Classical 1.4301 Austenitic Grades

In the recent situation of a historically high nickel price, austenitic stainless steels, such as 1.4301, became too expensive compared to their actual technical value in many applications. This paper presents two new stainless steel grades developed by ArcelorMittal to replace 1.4301. The first one is a 20%Cr ferritic grade. The second one is a low‐Ni Cu‐bearing austenitic grade. The choices in the compositions are described as a function of the technical requirements, economical target and the production process limitations. The final properties are discussed as a function of the composition and compared with 1.4301 and other existing stainless steels. Finally, the complementarities of these two new grades are highlighted in regard to the different application markets considered.     

Effect of Cold Deformation on Phase Evolution and Mechanical Properties in an Austenitic Stainless Steel for Structural and Safety Applications

 Abstract： The effects of cold deformation on the formation of strain induced α′ martensite and mechanical properties of an austenitic stainless steel have been examined. X-ray diffraction analysis has revealed that 30% and 40% cold rolling have resulted in the formation of 24% and 315% martensite respectively. Microstructural investigation has demonstrated that the formation of martensite is enhanced with increase in the percent deformation at 0 ℃. Investigation of mechanical properties reveals that hardness, yield strength and tensile strength values increase where as percent elongation drops with increasing deformation. The fractographic observation corroborates the tensile results. Examination of sub-surface at the fractured end of the tensile sample manifests that void/microcrack nucleation occurs in the interfacial regions of the martensite phase as well as at the austenite-martensite interface.     

不同冷轧压下量对亚稳态奥氏体不锈钢00Cr17Ni7织构的影响

 采用X射线衍射技术(XRD)研究了不同冷轧压下量对亚稳态奥氏体不锈钢00Cr17Ni7织构的影响,分析了亚稳态奥氏体不锈钢00Cr17Ni7中马氏体相和奥氏体相的织构变化情况。研究结果表明,不同冷轧压下量下,00Cr17Ni7中的奥氏体相织构主要由Brass{110}<112>、Goss{110}<001>和少量的Copper{112}<111>、S{123}<634>组成,并且随着压下量的增加Brass和Goss织构强度显著提高;同时马氏体相织构主要以{115}<110>、{112}<110> 、{111}<112>、{332}<113>组成,织构的形成主要归因于“Kurdjumov-Sachs取向关系”和“体心立方金属轧制织构类型演变的特点”共同作用的结果。     

Fracture Behavior of Cold Sprayed 304 Stainless Steel Coating During Cold Rolling

 The fracture behavior of cold sprayed 304 stainless steel coating in cold rolling process was studied. The 304 stainless steel coatings were deposited on low carbon steel substrate by cold gas dynamic spray (CGDS) and then cold rolled, respectively. The fracture morphology of the coatings was observed and analyzed, and the crack distributions along the longitudinal rolling direction of the coatings were also investigated and discussed. The results showed that the cohesive strength of the cold sprayed 304 stainless steel coating was too low to be cold rolled. Microcracks were formed in the as-sprayed coatings and ran perpendicularly to the rolling direction. The spacing distance between these cracks decreased with the increase of the cold rolling reduction. In addition, it was also found that the initial crack generated at the surface of the coating and propagated from the surface to the interface along the weakly bonded particles. A theoretical analysis was developed for the coating fracture. It gave a critical minimum cohesive bonding strength of the coating for non-breaking in cold rolling process. The crack propagation manner of the cold rolled coatings was also discussed.     

奥 氏 体 不 锈 钢 的 再 结 晶 动 力 学

 采用双道次压缩和应力松弛2种实验方法,研究了含铌奥氏体不锈钢347热变形后的再结晶动力学特征,确定了AVRAMI方程表达式,同时通过定量金相技术分析了对应2种实验方法的淬火试样中再结晶组织所占份数。比较不同实验方法所得结果可知：定量金相分析结果与应力松弛法结果较吻合,而与双道次压缩实验结果差异较大。仅进行1次应力松弛实验就可以得到一条再结晶率与时间的关系曲线,可大大减少实验量。     

海湾地区第1个不锈钢冷轧厂低成本生产优质不锈钢冷轧产品

讨论了即将建在海湾地区的第1个不锈钢冷轧厂的有关投资准则,重点包括影响工厂的初始投资成本以及运行成本的因素,所有这些与选择可生产高质量产品的设备有关.本项目代表着海湾投资公司在大型项目投资建设方面向前迈进了一大步.海湾公司将这一全部交钥匙项目建设合同交给达涅利公司本身就表明双方的相互信任.这种相互信任是两家公司在项目执行运作过程建立起来的.目前已经组建了1家新公司来经营和运作新建的冷轧厂,这家公司就是联合不锈钢公司(USCO).     

热轧奥氏体不锈钢带钢酸洗工艺机理分析

 详细分析了热轧奥氏体不锈钢带钢的表面氧化皮形成机理、退火对氧化皮特性的影响机理、酸洗工艺机理。结论是：热轧奥氏体不锈钢带钢表面氧化皮外层主要以铁氧化物为主,内层主要以交替分布的Cr2O3和FeCr2O4层为主;退火后,氧化皮结构变得疏松多孔,且易脱落,贫铬层厚度增加,带钢更加容易酸洗;酸洗时,带钢表面的氧化皮主要通过机械剥离作用去除。分析结果对热轧奥氏体不锈钢带钢酸洗技术的改进具有一定的理论指导意义。