金刚石涂层Si_3N_4刀具高速切削Inconel 718合金实验研究

在高速切削加工铬镍铁耐热合金(Inconel 718)的过程中,对加工表面质量的严格控制是获得高可靠性、长寿命工件的前提。利用热丝化学气相沉积(HFCVD)法在Si_3N_4刀具上涂覆一层金刚石薄膜,用于对Inconel 718合金进行加工。通过对Si_3N_4刀具磨损和工件表面加工硬化程度(DWH)的研究,寻找最优加工条件。结果表明,在切削深度0.75mm、进给量0.10mm/r、切削速度55m/min的加工条件下,Inconel 718合金工件获得较好的加工质量,同时Si3N4刀具的磨损较小。     

镍基合金Inconel718可切削加工性的试验研究

Inconel718是一种高强度耐热镍基合金,具有优良的高温强度、高温硬度和耐蚀性,在高温条件下能长期工作,已被广泛地应用于宇航工业、航空工业的涡轮发动机和相关零件的制造。分析Inconel718的机械性能、微观组织结构及其对切削加工性能的影响并进行了相关的试验验证,在试验数据的基础上,研究Inconel718中含碳量对切削过程中刀具磨损的影响。试验结果表明,Inconel718中含碳量在刀具后刀面磨损中起着非常重要的作用,Inconel718合金中含碳量越高,合金中所含的细微硬质夹杂物也越多,在切削过程中使刀具产生严重的后刀面磨粒磨损,从而降低材料的切削加工性。     

Inconel718合金扩散连接接头的组织与性能研究

对细晶Incone1718高温合金无中间层和加Ni箔中间层两种情况下的扩散连接进行了研究,分析了不同的连接温度、连接压力、连接时间等工艺参数对接头剪切强度的影响;通过SEM、EPMA和金相技术对接头微观组织和力学性能进行了分析.确定了获得优质接头的最佳工艺参数区间,即扩散连接温度T=1 050℃,连接压力P=20 MPa,连接时间t=45 min,选用Ni箔作为中间层,厚度为25 μm.     

Joining zirconia with nickel-based superalloys for extreme applications by using a pressure-free high-temperature resistant adhesive

In order to meet the high demand for joining ceramic/superalloy composite structure in extreme environments, a novel high-temperature resistant adhesion technique was developed for joining ZrO₂ and Inconel 625 by applying an aluminum phosphate emulsion/zirconium sol based adhesive. With increasing temperature, a series of reactions occurred in adhesive, and its high-temperature bonding was attributed to the formation of a composite structure containing various ceramics and intermetallics. The adhesive after RT curing could find direct applications in extreme environments, and provide bonding strength no less than 2.5 MPa in the temperature range of RT-1100 °C. The bonding strength was higher than 4 MPa in the temperature range of 800–1000 °C, which was further attributed to the formation of an effective CTE-gradient relationship among ZrO₂, adhesive and Inconel 625, as well as the interfacial reactions between the two substrates. The work broadened the application of adhesion technique and brought new ideas for joining dissimilar engineering materials.     

On chemical and diffusional interactions between PCBN and superalloy Inconel 718: Imitational experiments

During a metal cutting process, chemical wear can become the dominant mechanism of tool degradation under the high temperatures and contact pressures that arise between the tool and the metal workpiece. This study focuses on the chemical and diffusional interactions between superalloy Inconel 718 and cubic boron nitride (cBN) tool material with and without TiC binder. It covers thermodynamic modeling and experimental tests in the pressure range of 0.1 Pa to 2.5 GPa at temperatures up to 1600 °C. The methods used include diffusion couples under both vacuum and high pressure, transmission electron microscopy (TEM) analysis and in-situ synchrotron observations. It is shown that cBN is prone to diffusional dissolution in the metal and to reactions with niobium, molybdenum, and chromium from Inconel 718. Adding TiC binder changes the overall degradation process because it is less susceptible to these interaction mechanisms.     

Grain size modeling of a Ni-base superalloy using cellular automata algorithm

Nickel-base superalloys are used in highly demanding applications such as energy and aerospace industries. These alloys present good corrosion resistance, weldability and mechanical stability at high temperatures. Numerical methods are commonly used to predict the mechanical and microstructural behavior of heat resistant alloys. The aim of the present work was to model recrystallized grain size evolution under isothermal conditions using the cellular automata (CA) technique. The CA model was applied to simulate hot compression of Inconel 718 nickel-base alloy at 980 °C and 1020 °C. A finite element analysis was conducted to acquire input parameters to the model such as strain and strain rate. Hardening and recovery coefficients were calculated in order to represent the competitive effects during deformation. The influence of local changes of initial grain with fully and partial recrystallized microstructures were simulated by CA and compared with isothermal hot compression results. The model was able to comprehensively predict necklace type microstructures. The average grain size was generally in good agreement with the experimental data.     

Effect of deposition modes on electron beam directed energy deposited inconel 718

Inconel 718 thin walls were fabricated via electron beam directed energy deposition (EB-EDE) to investigated their microstructure and mechanical properties in terms of the deposition modes. Results revealed that the deposition modes had great effects on the microstructural evolution and thus influenced the mechanical properties. The layered nature and the fine dendrites were produced by the intermittent deposition, while the coarse and irregular cellular crystals were formed under the continuous deposition. The harmful Laves phase was precipitated under both deposition modes. The microhardness and tensile strength of the build-ups deposited intermittently were higher because there were fewer Laves phase. This work provided a new perspective to explain the microstructure differences of multi-layered components formed by EB-DED.     

Microstructure and mechanical properties in the TLP joint of FeCoNiTiAl and Inconel 718 alloys using BNi2 filler

High entropy alloy(HEA) of Fe Co Ni Ti Al and Inconel 718 superalloy were firstly transient liquid phase(TLP) bonded by BNi2 filler due to the diffusion of Si and B in the filler to the base metals. The effects of bonding time on microstructure evolution and mechanical properties of the TLP joints were investigated.Owing to the complete isothermal solidification of the joints bonded for 30 min 120 min at 1100°C,no athermally solidified zones(ASZs) formed by eutectic phases were observed in the welded zone. Thus the TLP joints were only composed by the isothermally solidified zone(ISZ) and two diffusion affected zone(DAZ) adjacent to the dissimilar base metals and the negative effect of the ASZ on joint properties can be avoided. In addition, the increase of the bonding time can also make the Ti B2 borides precipitated in the DAZ near HEA and the brittle borides or carbides in the DAZ near IN718 alloy decrease and reduce the possibility of the stress concentration happened in the joints under loading. Therefore, the highest shear strength(632.1 MPa) of the TLP joints was obtained at 1100°C for 120 min, which was higher than that of the joint bonded for 30 min, 404.2 MPa. Furthermore, the extension of the bonding time made the fracture mechanism of the joint be transformed from the intergranular fracture to the transgranular fracture. However, as the brittle borides in the DAZ near IN718 can not be eliminated completely and refining of grains also happened in such region, all the TLP joints fractured inner the DAZ near IN718 alloy.     

Inconel 690管子胀接工艺试验

介绍了Inconel 690管子与SA-508Ⅲ管板液压胀接试验，包括试验的内容以及为满足要求而采用的工艺参数及方法。