保温时间和钎焊温度对真空钎焊304不锈钢接头性能的影响

研究了镍基钎料真空钎焊304不锈钢的保温时间和钎焊温度这两种工艺参数对其焊缝组织和接头性能的影响.结果表明:适当的保温时间和钎焊温度有利于钎料与母材间的扩散作用,并能有效的消除钎缝组织中Ni-P、Ni-Cr-P等脆性化合物相,使得脆性化合物相在钎缝中的分布的连续性被打断,从而获得更高的接头强度.     

The Study of Plasma Nitriding of AISI304 Stainless Steel

This paper presents results on the plasma nitriding of AISI 304 stainless steel at different temperatures in NH3gas. The working pressure was 100～200 Pa and the discharge voltage was 700～800V. The phase of nltrided layer formed on the surface was confirmed by X-ray diffraction. The hardness of the samples was measured by using a Vickers microhardness tester with the load of 50g. After nitriding at about 400℃ for two hours a nitrided layer consisting of single γN phase with thickness of 51.tm was obtained. Microhardness measurements showed significant increase in the hardness from 240 HV (for untreated samples) up to 950 HV (for nltrided samples at temperature of 420℃). The phase composition, the thickness, the microstructure and the surface topography of the nltrided layer as well as its properties depend essentially on the process parameters.     

两种钎料对不锈钢钎焊接头组织和力学性能的影响

采用四号锰基钎料真空钎焊2Cr13不锈钢,研究了钎焊温度对其接头组织和室温及高温剪切强度的影响,并与Ni-Cr-P钎料钎焊不锈钢接头进行了对比.结果表明:四号锰基钎料钎焊接头组织由Mn-Ni基的单相Mn-Ni-Cu-Fe-Cr-Co固溶体组成,接头室温剪切强度随着钎焊温度的升高逐渐增加;Ni-Cr-P钎料钎焊接头组织由Ni-Fe基固溶体和Ni(Cr,Fe)-P化合物组成,接头室温剪切强度低于四号锰基钎料钎焊接头的室温剪切强度.当测试温度超过500℃时,Ni-Cr-P钎料钎焊接头的高温剪切强度降低幅度不大,四号锰基钎料钎焊接头降低明显,但仍高于Ni-Cr-P钎料钎焊接头的高温剪切强度.     

304不锈钢棒材的力学性能研究

针对某厂生产的304不锈钢出现的表面裂纹及凹坑等缺陷,测定了该钢种直径为15 mm棒材在750~1 350℃内的强度及塑性,并分析其断裂方式及高温组织。结果表明,1 200℃之后试样的抗拉强度降低至30 MPa以下,屈服强度降低至20 MPa以下,高温强度变差;断面收缩率在800~900℃之间为65%以上,1 040~1 220℃其值平均为70%,塑性较好;在950~1 020℃的低塑性区范围内,试样的断裂方式为延晶断裂;1 300℃时的高温组织为奥氏体与少量不规则铁素体。     

空泡腐蚀后304不锈钢表面的微观组织和力学性能研究

以304不锈钢为对象,研究空泡腐蚀后不锈钢表面微观组织与力学性能。结果表明,空泡腐蚀1 h后,表层的硬度和弹性模量均较空白试样有所升高,且随阳极极化电位的变化而变化。     

AISI304不锈钢渗铜后的微观组织及抗菌性能

以CuO＋NH4Cl为渗剂对AISI 304不锈钢表面进行化学渗铜处理,获得了具有优良抗菌性能的渗铜层。用扫描电镜及小掠射X射线衍射仪分析了渗层深度、微观组织及相组成。试验结果表明,当渗铜处理温度大于900℃后,渗铜层深度及渗层中富铜相Cu9.9Fe0.1及Cu3.8Ni的生成量快速增加。渗层中富铜相生成量越多,不锈钢的抗菌效果越佳,尤其是金黄色葡萄球菌。AISI304不锈钢经950℃保温4h渗铜处理后得到了较深的渗铜层,铜以富铜相形式均匀分布于渗层,具有优良的抗大肠杆菌和金黄色葡萄球菌的效果。     

Rapid Tempering of Martensitic Stainless Steel AISI420: Microstructure,Mechanical and Corrosion Properties

In this research, the effect of rapid tempering on the microstructure, mechanical properties and corrosion resistance of AISI 420 martensitic stainless steel has been investigated. At first, all test specimens were austenitized at 1050 °C for 1 h and tempered at 200 °C for 1 h. Then, the samples were rapidly reheated by a salt bath furnace in a temperature range from 300 to 1050 °C for 2 min and cooled in air. The tensile tests, impact, hardness and electrochemical corrosion were carried out on the reheated samples. Scanning electron microscopy was used to study the microstructure and fracture surface. To investigate carbides, transmission electron microscopy and also scanning electron microscopy were used. X-ray diffraction was used for determination of the retained austenite. The results showed that the minimum properties such as the tensile strength, impact energy, hardness and corrosion resistance were obtained at reheating temperature of 700 °C. Semi-continuous carbides in the grain boundaries were seen in this temperature. Secondary hardening phenomenon was occurred at reheating temperature of 500 °C.     

爆炸加载下AISI304不锈钢板表面硬化和数值模拟

目的 提高AISI304不锈钢板表面硬度。方法 利用爆炸加载表面硬化方法对3 mm厚的AISI304不锈钢板进行了表面硬化处理,通过HXD-1000YM型显微硬度计和JEM-2010型透射电子显微镜对爆炸加载处理后试样的不同部位横截面进行了硬度测量和微观组织表征。采用大型有限元数值模拟软件ANSYS/LS-DYNA对爆炸加载表面硬化过程进行了数值模拟,计算了撞击面平均压力和速度。通过对比数值模拟结果与理论计算结果,分析了特征点碰撞压力和速度对爆炸加载处理后表面硬度的影响。结果 数值模拟结果表明,撞击面压力平均值为5.5 GPa,撞击面平均速度达到了178 m/s,撞击面压力和速度的理论计算值与数值模拟值误差不超过5%。试验结果与数值模拟结果具有一致性。爆炸加载后,试样近起爆端和爆轰末端的撞击压力和撞击速度小于稳定爆轰阶段,导致前者表面硬度小于后者。横截面硬度分布表明撞击表面硬度大于炸药接触面硬度,撞击表面硬度值从210HV提高至450HV,炸药接触面硬度值从210HV提高至390HV。结论 爆炸表面硬化过程中存在边界效应。爆炸表面硬化方法能够显著提高板材表面硬度,同时可以提高板材整体硬度,且硬度提高与变形带和位错阵列形成有关。     

AISI304奥氏体不锈钢低温离子渗碳工艺优化研究

用正交实验法研究了AISI304奥氏体不锈钢低温离子渗碳工艺。结果表明,优化后的奥氏体不锈钢低温离子渗碳工艺参数为渗碳温度500℃、C3H8：H2=1：30、氩气流量20ml／min、渗碳时间6h。用优化工艺参数处理的奥氏体不锈钢表面可获得单一的Sc相组织,硬度高达780HV0．05。     

低温离子渗氮时间对304不锈钢渗层的影响

对304奥氏体不锈钢进行400 ℃不同时间的离子渗氮处理.利用光学显微镜、轮廓仪、能谱仪、X射线衍射仪和显微硬度计研究了经渗氮处理后试样改性层的表面形貌、微观结构、相组成和性能等.结果表明,随着渗氮时间的延长,试样表面的粗糙度、渗层厚度、表面氮含量、显微硬度基本呈线性增加;X射线衍射分析表明,在400 ℃不同时间的渗氮层为单一S相,并无CrN相析出.     

304L不锈钢高温变形组织的演化

采用Gleeble-1500D热/力学模拟试验机对304 L不锈钢铸态及锻态试样进行了热压缩试验研究,工艺参数为：变形温度950℃～1 150℃、变形量0.7,变形速率0.1s-1。结果表明：铸态的峰值应力低于锻态的峰值应力,铸态组织的动态再结晶明显迟于锻态组织;铸态及锻态304L不锈钢流变应力随着温度的升高而降低;随着变形温度的升高,动态再结晶百分数增加,再结晶组织增多并趋于完全。     

AISI 304奥氏体不锈钢低温离子渗碳工艺优化研究

用正交实验法研究了AISI 304奥氏体不锈钢低温离子渗碳工艺。结果表明,优化后的奥氏体不锈钢低温离子渗碳工艺参数为渗碳温度500℃、C3H8:H2=1:30、氩气流量20 ml/min、渗碳时间6 h。用优化工艺参数处理的奥氏体不锈钢表面可获得单一的Sc相组织,硬度高达780 HV0.05。     

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.     

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...     

304不锈钢双辉等离子渗铜铪表面合金层组织及抗菌性能

利用双辉渗金属技术在304不锈钢表面进行铜铪共渗,使用光学显微镜、X射线衍射仪和扫描电镜研究铜铪共渗合金层的显微组织、相结构、形貌、成分和表面硬度,采用薄膜密贴法对合金层进行抗菌性能的检测。结果表明:铜铪共渗合金层由扩散层和沉积层构成,合金层表面组织致密、分布连续、无明显裂纹和孔隙。铜、铪含量由表至里逐渐减少,渗铜铪试样中的铬和碳都出现向渗层表面迁移的现象。抗菌检测中,铜铪合金层表面对大肠杆菌和金黄色葡萄球菌都具有优良的抗菌性能,抗菌率均达到99%以上。当铜在源极棒中比例达到80%和90%时,所得到的渗铜铪试样抗菌率分别为99.83%和99.12%,当铜比例为70%时得到渗后试样的抗菌率仅为93%。渗后试样表面硬度约为605 HV0.1,大于渗铜试样和304不锈钢表面硬度。     

保温时间对不锈钢/碳钢钎焊接头性能的影响

采用碳钢/不锈钢Ni-P箔带钎焊工艺,研究了钎焊温度为1 000℃时,不同保温时间对焊接接头组织和性能的影响。结果表明,焊接接头组织主要为Ni3P脆性相和Ni基固溶体。延长保温时间可以减少钎缝中心区块状脆性相的数量,增加不锈钢侧的颗粒状的脆性相,提高接头剪切强度。     

AISI316L不锈钢等离子氮碳共渗层的表征

奥氏体不锈钢通过等离子氮碳共渗可显著提高其表面硬度,从而提高耐磨性而又不损害其抗腐蚀性能。本文采用光学显微镜、显微硬度和微磨损试验对经于450℃等离子氮碳共渗的AISI316L不锈钢和所获得的渗层进行了表征。结果证明,等离子氮碳共渗层由氮化铬析出相和富氮奥氏体基体组成,其硬度约850HV;渗层总深度平均约为45μm,且很均匀;渗层的耐磨性大大高于基体。     

Failure Analysis of an Oxidative Chlorination Reactor Clad with AISI 304L Stainless Steel

Failure analysis of the hermetical AISI 304L stainless steel cladding in oxidative chlorination reactor shows that its pitting and stress corrosion arose due to the presence of chlorine ion in the working environment. In order to improve its corrosion resistance, AISI 316L stainless steel should be utilized.     

钛催渗低温离子渗氮对304不锈钢组织性能的影响

目的 在保障304奥氏体不锈钢良好耐蚀性前提下,研发显著改善表层硬度及耐磨性的低温高效离子渗氮技术。方法 低温离子渗氮时,在试样周围均匀放置微量海绵钛,研发304奥氏体不锈钢创新钛催渗低温离子渗氮技术。采用光学显微镜、扫描电子显微镜、能谱分析仪、X射线粉末衍射仪、显微维氏硬度计、摩擦磨损测试仪,以及电化学工作站等设备分别对试样截面显微组织、物相及成分、截面显微硬度、渗层耐磨性能、耐蚀性能等渗层组织性能进行测试与分析。结果 304奥氏体不锈钢在420 ℃/4 h钛催渗离子渗氮处理后,不仅保持了良好耐蚀性,且渗层耐蚀性比常规低温离子渗氮略有提升,同时,表面硬度与耐磨性大幅提高,表面硬度由常规离子渗氮的978HV0.025提升至1350HV0.025。磨损率由20.9 μg/(N.m)降低至7.4 μg/(N.m),下降了约2/3。特别有价值的是,钛催渗低温离子渗氮效率比传统离子渗氮显著提升,渗氮层厚度由常规离子渗氮的11.37 μm增厚到48.32 μm,即渗氮效率提高到常规离子渗氮的4倍以上。结论 本研究研发的钛催渗低温离子渗氮技术在保障304奥氏体不锈钢优良耐蚀性的同时,能够大幅度提升不锈钢表面硬度及耐磨性能,且具有显著的催渗效果。     

Microstructure and Low-Temperature Mechanical Properties of 304 Stainless Steel Joints by PAW + GTAW Combined Welding

Journal of Materials Engineering and Performance - The combined double-pass process of plasma arc welding (PAW) + gas tungsten arc welding (GTAW) was performed on 304 austenitic...