Thermomechanical Behavior and Corrosion Resistance of a 316 L Austenitic Stainless Steel

Hot-formed components are constantly exposed to hostile environments with corrosive substances. Microstructural changes caused by thermomechanical processing can be predicted to increase the corrosion resistance of austenitic stainless steels. The objective of this study is to understand the relationship between the dynamic softening mechanisms and corrosion resistance, thus optimizing the hot-forming process. In the current work, the dynamic recrystallization (DRX) behavior of AISI 316 L austenitic stainless steel was studied in the temperature range of 1273 - 1423 K and strain-rate range of 0.1 - 5.0 s-1 using physical simulation. Subsequently, potentiodynamic polarization tests and scanning electron microscopy were performed on the hot-deformed samples to investigate the influence of temperature and strain-rate on the corrosion resistance and mechanical properties. The results indicated that the DRX fractions increased under low-temperature and high strain-rate conditions, resulting in grain refinement. The potentiodynamic polarization tests indicated that the dynamically recovered samples demonstrated high resistance to corrosion compared with the DRX samples. The best route found for the investigated alloy was for the strain to be applied at a temperature of 1423 K and a strain rate of 0.1 s-1.

不同碳含量铸态316L不锈钢的组织和性能研究

利用真空感应熔炼制备了不同碳含量的316 L铸态合金。利用化学分析方法分析了合金的化学成分,利用扫描电镜观察了合金的铸态微观组织,利用显微硬度仪测量了合金的维氏硬度。研究发现,合金的铸态组织由奥氏体和铁素体组成,随合金中的碳含量增加,合金铸态组织中的铁素体含量增加,合金的硬度显著增加。

316L奥氏体不锈钢QPQ盐浴复合处理后的显微组织分析

采用逐层X射线衍射和扫描电镜研究了316L奥氏体不锈钢经QPQ盐浴复合处理后的显微组织。结果表明,渗层组织由表面约10μm厚的Fe3O4和-ξFe2N混合层组成,最内层为含氮扩展奥氏体(S相),在混合层和S相之间为γ-′Fe4N相。在距离表面约10μm的地方,氧含量较高;随着厚度增加并超过10μm时,氧浓度急剧下降,而N浓度随着厚度的增加在约10μm的厚度处达到峰值,之后急剧下降再稍稍升高。

铜包覆石墨烯增强316L奥氏体不锈钢力学性能研究

采用分子水平混合和低速球磨的方法制备铜包裹石墨烯/316 L不锈钢复合粉体,通过放电等离子烧结制备石墨烯增强316 L奥氏体不锈钢复合材料,研究铜及石墨烯对复合材料密度、硬度和拉伸性能的影响,并对拉伸断口形貌进行了分析.结果表明:通过分子混合和球磨混合可制备铜包裹石墨烯与不锈钢均匀混合的复合粉体.烧结过程石墨烯结构保持完整.铜包裹石墨烯增强体可明显改善烧结不锈钢复合材料的密度、硬度、抗拉强度和屈服强度,使其分别提高3.6%、17.4%、35.8%和34.5%.

奥氏体不锈钢316L与双相不锈钢2205的焊接工艺及问题分析

阐述了不锈钢的类型和抗腐蚀原理,介绍了奥氏体不锈钢316L与双相不锈钢2205的焊接工艺,并在分析不锈钢大管道焊接特点的基础上,对氩弧焊打底充氩方式进行调整,保证了焊接过程中不发生背面氧化问题。

Microstructure evolution and mechanical properties of 316L austenitic stainless steel with aluminum addition by warm rolling

Microstructure evolution and mechanical properties of 316L austenitic stainless steel with aluminum addition by warm rolling at 550 ℃ were investigated. It is found that sample is composed of an ashen austenite matrix, a gray black ferrite phase and a small number of NiCx. The average grain sizes are 21.62, 19.66 and 19.49 μm for samples with the rolling deformation of 30%, 50% and 70%, respectively. The yield strength and tensile strength of samples with solid solution time of 30 min and deformation of 70% are higher. The fracture modes are similar and belong to toughness fracture. The fracture surfaces of the samples are composed of relatively large equal-axis ductile dimples （5-15 μm） and fine scattered ones around the dimples （〈 5 μm）. As the rolling deformation increases, the quantity of subgrain boundary increases and the 〈 101 〉 orientation is more prominent. {001 } 〈 110 〉 rotation-cube textures are present in ferrite phase of samples and weak Goss texture is formed in austenite pole images.

Surface modification of 316L stainless steeldiamond-like carbon films

The diamond-like carbon(DLC)film on 316L stainless steel substrate was preparedpulsed plasma-enhanced chemical vapor deposition,and the performance of the films was optimizedregulating the pulse voltage.Microstructure and properties of DLC film on 316L stainless steel were characterizedatomic force microscopy,field-emission scanning electron microscopy,Raman spectra,nano-indenter and electrochemical workstations.The results showed that DLC films with smooth and dense morphology have a low friction coefficient and high nano-indentation hardness,and the surface hardness of 316L stainless steel substrate was enhancedmore than 3 times.The mechanical properties of DLC films and their bond with 316L stainless steel could be further optimizedincreasing pulse voltage.DLC films on 316L stainless steel substrate increased the self-corrosion potential0.173 V and decreased self-corrosion current99%,which significantly improved the anti-corrosive properties of 316L substrate.

Crevice Corrosion Behaviors Between CFRP and Stainless Steel 316L for Automotive Applications

Carbon fiber reinforced plastics (CFRP) are promising lightweight materials for vehicle applications. 316L is one of the most widely used types of austenite stainless steels and applied in lots of automotive applications. The existence of crevices will result in galvanic corrosion and crevice corrosion when CFRPs and 316L are directly connected. A crevice former for the galvanic system was therefore designed and applied to evaluate the crevice corrosion behaviors and study the mechanism of galvanic crevice corrosion through several electrochemical techniques in this research. The results showed that the crevice corrosion of galvanic systems grew from crevice mouth to the inside crevice and could be divided into four steps, metastable pitting corrosion at the crevice mouth, initiating step of crevice corrosion, propagating step and ending step of crevice corrosion. Because of the influences of the galvanic system, electrode reaction rates were speeded up and the passivation region was shortened at the initiating stage of crevice corrosion. Corrosion rate was observed to be higher in the galvanic system than that in normal crevice systems.

纳米多晶316L奥氏体不锈钢高温蠕变行为的原子尺度研究

通过分子动力学模拟研究了纳米多晶316L奥氏体不锈钢在不同峰值应力下的高温蠕变变形行为和蠕变机制.数值模拟结果表明纳米多晶316L奥氏体不锈钢的高温蠕变变形是由位错、晶粒内部和晶界扩散以及晶界滑移之间的交互作用引起.在初始蠕变和稳态蠕变阶段,纳米多晶316L奥氏体不锈钢高温蠕变的主导性机制是晶粒内部和晶界的扩散以及晶界的滑移.在加速蠕变阶段,一些晶界被摧毁后,位错滑移成为纳米多晶316L奥氏体不锈钢的主要蠕变机制.这项工作旨在揭示纳米多晶316L奥氏体不锈钢的高温蠕变机理,为增强型抗蠕变316L奥氏体不锈钢的设计和制造提供指导.