Strain Rate Sensitivity of Pre‐Strained AISI 301LN2B Metastable Austenitic Stainless Steel

The dynamic behavior of AISI 301LN2B (EN 1.4318) metastable austenitic steel grade has been investigated at 296 K by means of servohydraulic tensile and split Hopkinson bar testing in the strain rate range 0.005–1000 s^?1. As delivered, as well as 10% uniaxial, biaxial, and plane strain pre‐strained conditions, without subsequent heat treatment have been tested. A negative strain rate sensitivity is observed in the low strain rate range between 10^?4 and 1–10 s^?1. Pre‐straining reduces the magnitude of the adiabatic tensile strength softening, especially in the plane strain condition with higher triaxility. The thermal activation related dynamic flow stress increase is not dependent on pre‐straining. The γ → α′ induced additional flow stress increase, however, is highly strain rate and pre‐straining sensitive. The amount of pre‐straining determines the overall ductility at fracture, and therefore the adiabatic temperature increase. The pre‐straining stress state influences the amount of α′‐martensite formed before dynamic testing, and consequently the maximum intensity of the TRIP induced flow stress increase by subsequent dynamic testing.     

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。     

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.     

Reverse Martensitic Transformation and Resulting Microstructure in a Cold Rolled Metastable Austenitic Stainless Steel

The reverse martensitic transformation in cold‐rolled metastable austenitic stainless steel has been investigated via heat treatments performed for various temperatures and times. The microstructural evolution was evaluated by differential scanning calorimetry, X‐ray diffraction and microscopy. Upon heat treatment, both diffusionless and diffusion‐controlled mechanisms determine the final microstructure. The diffusion reversion from α′‐martensite to austenite was found to be activated at about 450°C and the shear reversion is activated at higher temperatures with A_f′ ~600°C. The resulting microstructure for isothermal heat treatment at 650°C was austenitic, which inherits the α′‐martensite lath morphology and is highly faulted. For isothermal heat treatments at temperatures above 700°C the faulted austenite was able to recrystallize and new austenite grains with a low defect density were formed. In addition, carbo‐nitride precipitation was observed for samples heat treated at these temperatures, which leads to an increasing M_s‐temperature and new α′‐martensite formation upon cooling.     

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.     

冷变形工艺对SUS301L不锈钢组织性能的影响

对亚稳定奥氏体不锈钢SUS301L进行了不同变形量的冷轧,并分别用X射线衍射仪和MP30铁素体测量仪测出了应变诱导马氏体及其含量.采用金相显微镜观察了试样的组织演变.研究结果表明:形变马氏体在剪切带的交叉点形核,新晶核的不断形成促使了形变马氏体的长大;形变马氏体随着冷轧压下量的增加而增加;另外,抗拉强度和硬度的增加幅度相当;平均抗拉强度与平均显微硬度的比值在2.82～3.17之间.     

冷轧变形量对304不锈钢力学性能的影响

 研究304奥氏体不锈钢薄板的硬度随冷轧变形量的变化规律,为奥氏体不锈钢薄板工业生产提供指导。同时,采用金相显微镜、维氏硬度测量、X-射线衍射仪和透射电镜研究了不同变形量冷轧对304不锈钢显微组织和机械性能的影响。在室温对0.5mm厚退火板材进行冷轧,使冷轧变形量从10%增加到52%。结果表明,形变诱发马氏体相变是导致304不锈钢冷轧时产生加工硬化的主要原因,冷轧可以显著提高钢的强度和硬度。当冷轧变形至40%时,304不锈钢的维氏硬度是未变形时的2.2倍,屈服强度、抗拉强度分别增大到未变形时的4.2倍（880MPa）和1.8倍（1312MPa）。     

304与301B奥氏体不锈钢在线固溶热处理工艺研究

通过双道次热压缩和热轧试验研究了在线固溶热处理工艺对304和301B奥氏体不锈钢组织和性能的影响,提高终了压缩温度、冷却速度,降低卷取温度,可以改善奥氏体不锈钢微观组织,减少碳化物析出,提高抗晶间腐蚀能力和力学性能.将该工艺应用于工业生产的304奥氏体不锈钢热轧卷板,测试结果表明304各项性能得到改善,冷轧前退火工序可被在线固溶取代.     

铜对奥氏体抗菌不锈钢性能的影响

 研究了不同铜含量的奥氏体抗菌不锈钢的抗菌性能、腐蚀性能和力学性能。样品经过热轧、抗菌热处理、冷轧、退火处理后,进行了抗菌试验、腐蚀试验等。试验结果表明,随着铜含量的增加,抗菌性逐渐提高;其耐点蚀性随着铜含量的增加呈提高的趋势;强度随着铜含量的增加先减后增,塑性先增后减。     

301奥氏体不锈钢薄板拉伸强度与冷轧硬度之间的关系

 为对冷轧不锈钢薄板的产品硬度控制提供指导,尝试用一个新的方法来取代试轧,既达到控制冷轧板硬度的目的,又能降低成本、提高效率。对099mm厚的经过退火的301奥氏体不锈钢薄板进行冷轧减薄,并进行室温拉伸试验,测量其维氏硬度。通过观察金相和利用X射线衍射,验证了应变诱导马氏体相变是导致301奥氏体不锈钢冷轧和拉伸时产生加工硬化的主要原因。试验结果表明,冷轧和拉伸有着相似的加工硬化趋势,综合拉伸与轧制试验数据,确定了拉伸强度与冷轧硬度之间的关系,实现了通过拉伸强度来得到对应应变下的冷轧硬度,具有很好的预见性。冷轧可以提高301不锈钢的强度和硬度,显著改善其力学性能。     

氮对304奥氏体不锈钢组织和力学性能的影响

在０Ｃｒ１８Ｎｉ９奥氏体不锈钢成分基础上，加入一定的氮，并使钢中的镍含量控制在标准下限含量的条件下，研究了氮对组织和力学性能的影响。结果表明：加氮后钢的强度提高，奥氏体稳定不变，固溶态组织不变，而敏化后晶界析出物类型有所不同。     

快冷工艺对冷轧双相钢组织性能的影响

以C-Si-Mn系相变强化冷轧高强度钢板为研究对象,研究了连续退火快速冷却工艺对冷轧双相钢组织和力学性能的影响。研究发现,对于双相钢,在连退冷却能力不足的情况下,需添加合金元素,使CCT曲线右移,降低双相钢的临界冷却速率;在提高连退快冷冷却速率的情况下,可以减少合金元素的添加量,节约成本。冷却速率越高,双相钢的强度越高,延性下降。     

Static Recrystallization Behavior of 316LN Austenitic Stainless Steel

The static recrystallization of 316LN austenitic stainless steel was studied by double-pass hot compression tests on a Gleeble-3500 thermomechanical simulator. The specimens were compressed at the deformation temperatures of 950, 1050, 1150 °C, strain rates of 0.01, 0.1, 1s^?1, strains of 0.1, 0.15, 0.2, and intervals of 1 — 100 s. The results show that the volume fraction of static recrystallization of 316LN increases with the increase of deformation temperature, strain rate, strain and interval, which indicates that static recrystallization occurs easily under the conditions of higher deformation temperature, higher strain rate and larger strain. Deformation temperature has significant influence on static recrystallization of 316LN. The volume fraction of static recrystallization could easily reach 100% at higher deformation temperatures. By microstructure analysis, it can be concluded that the larger the volume fraction of static recrystallization, the more obvious the grain refinement. The static recrystallization activation energy of 317 882 J/mol and the exponent n of 0.46 were obtained. The static recrystallization kinetics was established. The predicted volume fraction of static recrystallization is in good agreement with the experimental results.     

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。     

Sensitization Behaviour of Manganese‐Alloyed Austenitic Stainless Steels

Manganese is an essential alloying element in advanced austenitic stainless steels with specific properties such as high resistance to harsh corrosive environments, high strength or low material costs. These materials are often used for welded constructions which have to be highly corrosion resistant. Hence it has to be ensured that the heat input during welding does not initiate the precipitation of chromium carbide resulting in a susceptibility to intergranular corrosion. This leads to the question whether the sensitization behaviour of manganese‐alloyed austenitic stainless steels is comparable to that of the well‐known conventional chromium nickel austenites. In the present work the effect of heat‐input on the susceptibility of the CrNi‐steel 1.4301 and the CrNiMn‐steel 1.4376 to intergranular corrosion (IGC) was considered. Investigations were carried out by corrosion testing in the so‐called Strauss‐Test to elucidate the effect of the annealing temperatures on the microstructure. Furthermore, the influence of heat treatment on the mechanical properties was evaluated by tensile testing. As a result, it could be demonstrated that manganese‐alloyed austenitic stainless steels like grade 1.4376 exhibit a sensitization behaviour very similar to the conventional austenitic steel grades. The same kinds of tests on intergranular corrosion resistance can be applied for both types of materials.     

Microstructure Evolution of Laser Welded 301LN and AISI 304 Austenitic Stainless Steel

Metallurgical and Materials Transactions A - Cold-rolled plates of metastable austenitic stainless steel (SS) 301LN are the main materials for manufacturing lightweight railway passenger cars,...