热处理工艺对316L不锈钢微丝组织和性能的影响

分别对 316L不锈钢微丝拉拔过程中的几道丝材进行了退火处理 ,研究了退火温度与保温时间对不同压缩率丝材的显微组织与力学性能的影响。结果表明 ,再结晶后的显微组织为完全奥氏体组织。丝径为0 2 4 5mm(压缩率为 83% )与0 113mm(压缩率为 96 % )的丝材 ,采用 10 5 0℃× 10s的热处理工艺 ,其再结晶后的晶粒度可达 11级 ,并具有优良的力学性能。丝径为0 0 3mm微丝的最佳退火工艺为 10 5 0℃× 1s。     

加热规范对316LN铸态奥氏体不锈钢组织和性能的影响

研究了316LN奥氏体不锈钢在不同温度和不同保温时间下,铁素体的含量、形貌的变化规律以及对力学性能的影响.结果表明:随同溶温度的升高、固溶时间的延长,铁素体的含量逐渐减少,形貌由原来的骨骼状逐渐向比较光滑的圆点状演变,硬度有整体下降的趋势.     

热处理温度对大气等离子喷涂316L不锈钢涂层组织和性能的影响

目的研究316L不锈钢涂层在不同热处理温度下组织结构和性能的变化规律,提高该涂层的摩擦学性能。方法利用大气等离子喷涂(APS)技术制备316L不锈钢涂层,对喷涂态涂层进行300~700℃热处理。通过光学显微镜(OM)和X射线衍射仪(XRD)观察分析涂层的显微组织和相组成,利用维氏硬度计测试涂层的显微硬度值。采用摩擦磨损试验机和三维光学显微镜测试涂层的摩擦系数和磨损率,利用场发射扫描电子显微镜(FE-SEM)观察磨痕表面并对磨损机制进行深入分析。结果喷涂态316L不锈钢涂层的厚度约为350?m,显微硬度值为335HV0.1,涂层组织中含有未熔颗粒、孔隙和氧化物等。在干摩擦条件下,涂层的摩擦系数稳定在0.75左右,磨损率为(1.329±0.14)×10-5 mm3/(N·m)。随着热处理温度的升高,涂层扁平颗粒界面处的氧化行为明显,同时涂层内部的孔隙缩小,涂层结构更加致密,使得涂层显微硬度提高了30%。涂层的耐磨性能在700℃热处理条件下最佳,磨损率为(1.149±0.26)×10-5 mm3/(N·m),较喷涂态涂层降低14%,磨损机制以疲劳磨损和粘着磨损为主。结论热处理有助于提高316L不锈钢涂层的显微硬度,700℃热处理可有效提高涂层的耐磨性。     

生物医用材料316L不锈钢的磨损腐蚀特性研究

对人工关节常用的生物医用材料316L不锈钢在蒸馏水和Hank’s模拟体液条件下的腐蚀磨损行为进行了研究,通过改变载荷和磨损时间考察了不同因素对其腐蚀磨损的影响规律。在Hank’s模拟体液条件下,316L不锈钢在10kg载荷下的磨损比在其他载荷条件下都要小。同载荷条件下,该钢在Hank’s中的磨损量大于蒸馏水中的,并有晶间腐蚀倾向。     

不锈钢表面冷喷涂铜涂层组织和性能研究

采用冷喷涂技术在不锈钢表面喷涂纯铜涂层;涂层的断面形貌和硬度分别通过光学金相显微镜观察和显微硬度计测试,同时研究了涂层的结合机理.结果表明,粉末在沉积过程中存在低速粒子,部分低速粒子沿原路径反弹后影响其他粒子的沉积;纯铜涂层与基体的结合为机械结合;涂层内部兼有部分冶金结合;涂层的硬度分布较均匀,且高于纯铜的硬度.     

退火温度对微纳结构316L不锈钢组织和性能的影响

采用铝热熔化法制备了纳米晶/微米晶复相316L不锈钢,研究了铸态和600~1 000℃退火态下钢的组织和力学性能特征。结果表明:随退火温度升高,纳米晶和微米晶的平均晶粒尺寸逐渐增大,微米晶的体积分数逐渐提高。1 000℃退火后组织中出现了FeNiCrAl金属间化合物相。600℃退火后抗拉强度最大,约574 MPa,伸长率为6.5%。800℃退火后,拉伸屈服强度和抗拉强度分别降至240 MPa和515 MPa,伸长率升高至18.2%。1 000℃退火后拉伸屈服强度和抗拉强度进一步降低,但塑性提高,伸长率达到41.2%。     

Production of Annealed Cold-Sprayed 316L Stainless Steel Coatings for Biomedical Applications and Their in-vitro Corrosion Response

316L powders were successfully deposited onto Al5052 aluminium substrates by cold spray method. Annealing was treated on the coated samples at 250–1000°C temperatures under Ar atmosphere. The in vitro performances of the coatings have been compared with using electrochemical corrosion test technique in the simulated body fluid (SBF) at body temperature (37°C). A scanning electron microscope (SEM-EDS) and X-ray diffraction (XRD) have been used for microstructural characterization and phases identifications of the coatings, respectively. The results were shown that there are high adhesions at particle and substrate interfaces and between the particles deposited as well. Also, the increasing annealing temperature increases corrosion resistance of the cold sprayed 316L stainless steel coatings. The corrosion susceptibility of the coating annealed at 1000°C was similar that of standard 316L stainless steel implant material in Ringer’s solution. The microstructural observations revealed that corrosion starts between the inter-splat powders and continues throughout the surface not in-depth.     

Microstructure and Mechanical Properties of 316L Stainless Steel Filling Friction Stir-Welded Joints

Keyhole left at 316L stainless steel friction stir welding/friction stir processing seam was repaired by filling friction stir welding (FFSW). Both metallurgical and mechanical bonding characteristics were obtained by the combined plastic deformation and flow between the consumable filling tool and the wall of the keyhole. Two ways based on the original conical and modified spherical keyholes, together with corresponding filling tools and process parameters were investigated. Microstructure and mechanical properties of 316L stainless steel FFSW joints were evaluated. The results showed that void defects existed at the bottom of the refilled original conical keyhole, while excellent bonding interface was obtained on the refilled modified spherical keyhole. The FFSW joint with defect-free interface obtained on the modified spherical keyhole fractured at the base metal side during the tensile test due to microstructural refinement and hardness increase in the refilled keyhole. Moreover, no σ phase but few Cr carbides were formed in the refilled zone, which would not result in obvious corrosion resistance degradation of 316L stainless steel.     

超声纳米晶表面改性对选区激光熔化316L不锈钢微观结构和力学性能的影响

目的 改善选区激光熔化（Selectivelasermelting,SLM）316L不锈钢的表面完整性和力学性能。方法采用超声纳米晶表面改性（Ultrasonic Nanocrystal Surface Modification,UNSM）这一新兴表面塑性变形方法对SLM 316L不锈钢进行超声冲击强化,利用维氏硬度计、扫描电镜、白光干涉仪、EBSD、XRD等对处理前后材料的表面完整性、微观组织演变和塑性变形行为进行表征和分析。结果 经过UNSM处理后,SLM316L不锈钢的微观缺陷明显减少,初始未熔合孔隙发生闭合,表面粗糙度Ra由5.374μm降至0.510μm,表面硬度从230HV增至461.16HV;同时,材料表层发生了剧烈的塑性变形,形变诱导材料微观组织从γ相向α相转变,微观结构由初始不规则柱状粗晶转变为等轴状细晶。从EBSD表征结果可知,在材料表面形成了深度约为20μm的梯度纳米晶,材料内部存在明显的不均匀变形;与初始SLM试样相比,通过UNSM处理在材料表面引入了最大为932 MPa的残余压应力。结论 超声纳米晶表面改性能够显著改善SLM 316L不锈钢的表面完整性,形成较...     

Microstructure and Size-Dependent Mechanical Properties of Additively Manufactured 316L Stainless Steels Produced by Laser Metal Deposition

Metal additive manufacturing (AM), as a disruptive technology in the field of fabricating metallic parts, has shown its ability to design component with macrostructural complexity. However, some of these functionally complex structures typically contain a wide range of feature sizes, namely, the characteristic length of elements in AM-produced components can vary from millimeter to meter-scale. The requisite for controlling performance covers nearly six orders of magnitude, from the microstructure to macro scale structure. Understanding the mechanical variation with the feature size is of critical importance for topology optimization engineers to make required design decisions. In this work, laser metal deposition (LMD) is adopted to manufacture 316L stainless steel (SS) samples. To evaluate the effect of defects and specimen size on mechanical properties of LMD-produced samples, five rectangular sample sizes which ranged from non-standard miniature size to ASTM standard sub-sized samples were machined from the block. Tensile test reveals that the mechanical properties including yield strength (YS), ultimate tensile strength (UTS), and elongation to failure (ε_f) are almost the identical for samples with ASTM standard size. Whilst, relatively lower YS and UTS values, except for ε_f, are observed for samples with a miniature size compared with that of ASTM standard samples. The ε_f values of LMD-produced 316L SS samples show a more complex trend with sample size, and are affected by three key influencing factors, namely, slimness ratio, cluster of pores, and occupancy location of lack of fusion defects. In general, the ε_f values exhibit a decreasing trend with the increase of slimness ratio. Microstructure characterization reveals that the LMD-produced 316L samples exhibited a high stress status at low angle grain boundaries, whilst its location changed to high angle grain boundaries after plastic deformation. The grain size refinement and austenite-to-martensite phase transformation occurred during plastic deformation might be responsible for the very high YS and UTS attained in this study. The experimental works carried out in this study is expected to provide a guideline for evaluating the mechanical properties of LMD-produced parts with complex structure, where critical parameter such as a certain slimness ratio has to be considered.     

Effect of Heat Treatment on Microstructure and Mechanical Properties of A380 Aluminum Alloy Deposited by Cold Spray

The microstructure and mechanical properties of cold-sprayed bulk A380 alloy were investigated after heat treatment at various conditions, using optical and electron microscopy and tensile and hardness tests, respectively. The results revealed that heat treatment increased the strength and ductility of the cold-sprayed A380 alloy deposits compared with as-sprayed state. Heat treatment showed two different effects on the mechanical properties of the deposits. On the one hand, it resulted in effective diffusion at interparticle boundaries that altered the particle bonding mechanism from pure mechanical interlocking to metallurgical bonding. Thus, the strength and ductility of the material were greatly enhanced. On the other hand, interparticle diffusion during high-temperature heat treatment resulted in growth of the Si phase and pores, which ultimately reduced the strength and elongation of the alloy. This observation was consistent with the hardness results, which showed a decreasing trend with increase of the heat treatment temperature.     

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10 μm 厚的Fe3O4和ξ-Fe2N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10 μm的地方,氧含量较高;随着厚度增加并超过10 μm时,氧浓度急剧下降,而N浓度随着厚度的增加在约10 μm的厚度处达到峰值,之后急剧下降再稍稍升高.     

Al含量对316L不锈钢显微组织和力学性能的影响

研究了Al含量对316L不锈钢显微组织、力学性能和抗腐蚀性能的影响。结果表明,Al元素在热轧态316L不锈钢中的主要存在形式是固溶和第二相Al4C3。随着Al含量的增加,316L不锈钢的耐蚀性、屈服强度和抗拉强度升高,但其塑性降低。     

Effect of Heat Treatment on the Microstructure,Mechanical Properties and Corrosion Resistance of Selective Laser Melted 304L Stainless Steel

The influence of heat treatment holding temperatures from 600 to 1300 °C on the microstructure, mechanical properties and corrosion resistance in selective laser melted(SLMed) 304L stainless steel is investigated in this work. The results reveal that there is no remarkable microstructure change after holding at 600 °C for 2 h, while recrystallization leads to a slight decrease in grain size in the temperature range of 700–900 °C. The heat treatment at temperatures from 1000 to 1300 °C for 2 h ob...     

热处理对多层不锈钢复合材料组织和性能的影响

研究了用累积复合轧制技术制备的8层不锈钢复合材料,经(200～900)℃×(0.5～2)h热处理后,微观组织以及力学性能的变化。结果表明:在保温时间不变的条件下,随热处理温度升高,微观组织逐步经历了回复→再结晶→晶粒长大的过程,抗拉强度和硬度下降,塑性提高,600℃以上温度变化较为显著;在温度不变的条件下,随保温时间的延长,组织和力学性能变化不是很明显。试样弯曲90°试验未见明显分层和撕裂迹象,且拉伸试样均为韧性断裂。采用600℃×1 h的热处理制度,材料的综合力学性能较佳。     

Microstructure Characteristics and Mechanical Properties of Al-12Si Coatings on AZ31 Magnesium Alloy Produced by Cold Spray Technique

The cold spray technique was to deposit Al-12Si coatings on AZ31 magnesium alloy. The influence of gas pressure and gas temperature on the microstructure of coatings was investigated so as to optimize the process parameters. OM, SEM, and XRD were used to characterize the as-sprayed coatings. Mechanical properties including Vickers microhardness and adhesion strength were measured in order to evaluate coating quality. Test results indicate that the Al-12Si coatings possess the same crystal structure with powders, sufficient thickness, low porosity, high hardness, and excellent adhesion strength under optimal cold spray process parameters.     

激光熔覆316L不锈钢涂层组织和性能的研究

目的提高45#钢的使用性能和耐蚀性。方法以316L不锈钢粉末为熔覆材料,在45钢退火基体表面制备不锈钢熔覆层,采用CCD中心组合设计,利用金相法检测熔覆层的几何形貌参数,利用光学显微镜(OM)和扫描电镜(SEM)分析熔覆层的显微组织,采用显微硬度计和磨损试验机测试熔覆层的显微硬度和磨损性能,利用电位极化曲线测试熔覆层的耐腐蚀性能。结果当激光功率为600 W,扫描速度为22.5mm/s,送粉速率为0.18 r/min时,熔覆层与基体呈良好的冶金结合。熔覆层的硬度在461.3~559.8HV,是基材硬度的2倍左右;磨损量为0.0146 g,是基材的0.1倍;摩擦系数较为稳定,保持在0.5左右,是基材的0.3倍左右;自腐蚀电流密度为3.274×10~(-7) A/cm~2,是基材的0.7倍左右。结论在45钢表面激光熔覆316L不锈钢涂层后,可有效提高其耐磨性和耐蚀性。     

双相不锈钢在热处理过程中组织及性能的研究

采用光学显微镜、扫描电镜和电子显微镜对双相不锈钢在不同热处理温度下的显微组织、力学性能、相组织转变和耐蚀性等进行了研究。结果表明,随着热处理温度的升高,试验钢的硬度和强度不断降低,伸长率增加;适当降低Mo元素、提高Cr和C元素的质量分数和控制热处理温度可显著提高双相不锈钢力学性能和耐点蚀性能。     

激光快速成形316L不锈钢的组织及性能

基于一般快速成型原理，采用激光熔化同轴输送的316L不锈钢粉末，在沉积基板上逐层堆积出薄壁金属零件，所制零件组织致密，成分均匀，具有快速凝固组织特征，力学性能与铸态及铸造退火态相当，可满足直接使用要求。     

选区激光熔化成形316L不锈钢多孔结构及力学性能

基于选区激光熔化技术(SLM),制备了BCC、FCC、FCCZ 3种不同拓扑单元的316L不锈钢多孔结构,验证了该技术成形复杂多孔结构件的可行性。对试样进行了准静态压缩试验,得到了多孔结构在压缩过程中的变形模式和力学响应曲线,对比分析了3种结构试样的力学性能。结果表明,FCCZ型多孔结构的抗压性能和能量吸收特性均优于BCC型和FCC型结构;利用ABAQUS/Explicit软件进行准静态压缩仿真,仿真结果和试验结果基本符合。