铝及铝合金细化剂的研究

综述了晶粒细化剂的发展历史及细化剂的细化机理和各种细化剂的比较。并着重介绍了新一代的Al-Ti-C晶粒细化剂。     

铝及铝合金细化剂的研究

综述了晶粒细化剂的发展及历史，细化剂的细化机理和各种细化剂的比较。并着重介绍了新一代的AlTiC晶粒细化剂。     

铝合金管材晶粒度的细化研究

通过控制6063管材截面晶粒尺寸,来满足某高端汽车客户标准中100μm的晶粒尺寸要求;从铸棒的均质制度、模具设计方式、挤压工艺三个方面进行优化控制,通过高倍显微镜、电导率和布氏硬度等检测方法进行深入分析.结果表明,铸棒采用高温短时的均质制度,模具减少前室的设计方法,挤压工艺使用低温快速的挤压方式,成功生产出符合高端汽车...     

Grain Boundary Segregation Behavior of Boron in Low-Alloy Steel

The boron concentration profiles around prior austenite grain boundaries in Fe-0.05C-0.5Mo-0.001B (mass pct) are examined using aberration-corrected STEM-EELS. In order to obtain the precise distribution of boron around the boundaries, tilt series measurements with thin specimens (<30 nm) are performed and the EEL spectra are analyzed by principal component analysis (PCA) and multivariate curve resolution (MCR). The boron concentration profile changes with the cooling rate from the solid solution temperature. The concentration at grain boundaries is maximized at a medium rate (30 °C/s), where the concentration reaches 8 at. pct, and it decreases at a larger (250 °C/s) or smaller (5 °C/s) rate. On the other hand, the boron distribution becomes wider as the cooling rate becomes smaller. The current results suggest that the boron segregation in the alloy is formed by the “non-equilibrium segregation mechanism.”     

Effect of Inclusion and Filtration on Grain Refinement Efficiency of Aluminum Alloy

Metallurgical and Materials Transactions A - It is well known that the filtration efficiency of ceramic foam filters (CFF) on aluminum melt can be significantly reduced by the addition of grain...     

精铝及铝精炼

介绍了精铝的性质及用途,铝精炼的几种方法,包括三层液电解精炼法、偏析法和区域熔炼法等。     

Grain Boundary Behavior in an Ultrafine-Grained Aluminum Alloy

The low-angle grain boundary (LAGB) stability in an ultrafine-grained (UFG) Al alloy during monotonic loading was investigated by orientation imaging microscopy (OIM). The experiments show that boundaries with misorientation below ~2.5 deg are stable, while boundaries with misorientation between 2.5 and 15 deg are unstable. Similar results were observed during cyclic loading of UFG Al alloy. This behavior was rationalized using the nonequilibrium thermodynamics concept. On the other hand, it is postulated that the grain boundary behavior in microcrystalline alloy is different because of the larger dislocation mean free path.     

用于铝合金晶粒细化的中间合金研究现状与分析

本文讨论了用于铝合金晶粒细化的中间合金研究与应用现状 ,在分析细化机理的基础上对新型细化剂AlTiB　　Re中间合金进行了初步探讨 ,结果表明 ,该中间合金是一种高效长久的晶粒细化剂 ,其效果优于进口的Al5TiB细化剂     

Oxidation of Silicon and Boron in Boron Containing Molten Iron

 A new process of directly smelting boron steel from boron containing pig iron has been established. The starting material boron containing pig iron was obtained from ludwigite ore, which is very abundant in the eastern area of Liaoning Province of China. The experiment was performed in a medium frequency induction furnace, and Fe2O3 powder was used as the oxidizing agent. The effects of temperature, addition of Fe2O3, basicity, stirring, and composition of melt on the oxidation of silicon and boron were investigated respectively. The results showed that silicon and boron were oxidized simultaneously and their oxidation ratio exceeded 90% at 1 400 ℃. The favorable oxidation temperature of silicon was about 1 300-1 350 ℃. High oxygen potential of slag and strong stirring enhanced the oxidation of silicon and boron.     

控轧过程中KQ450钢的晶粒细化和析出物行为

通过定量金相、扫描电镜、透射电镜和X射线小角度散射方法研究KQ450微合金钢在不同控制轧制条件下,工艺参数对其铁素体晶粒细化和析出物行为的影响.结果表明:加热温度对KQ450微合金钢晶粒粗化比较敏感;析出相是面心立方结构的NbC,VC和V(CN).析出物的平均尺寸随冷却速度的增大而减小.     

Influence of Solute Content and Solidification Parameters on Grain Refinement of Aluminum Weld Metal

Grain refinement provides an important possibility to enhance the mechanical properties (e.g., strength and ductility) and the weldability (susceptibility to solidification cracking) of aluminum weld metal. In the current study, a filler metal consisting of aluminum base metal and different amounts of commercial grain refiner Al Ti5B1 was produced. The filler metal was then deposited in the base metal and fused in a GTA welding process. Additions of titanium and boron reduced the weld metal mean grain size considerably and resulted in a transition from columnar to equiaxed grain shape (CET). In commercial pure aluminum (Alloy 1050A), the grain-refining efficiency was higher than that in the Al alloys 6082 and 5083. Different welding and solidification parameters influenced the grain size response only slightly. Furthermore, the observed grain-size reduction was analyzed by means of the undercooling parameter P and the growth restriction parameter Q, which revealed the influence of solute elements and nucleant particles on grain size.     

LC4铝合金晶粒的超细化处理研究

对LC4铝合金常规热轧板材进行了由470℃固溶处理2小时水淬+400℃8小时过时效+210℃压下量为90％的温轧+510或470℃1/2小时再结晶退火等工序组成的晶粒超细化处理,制得了平均晶粒直径小于7.0μm,厚1.5mm的薄板。上述晶粒超细化处理工艺参数中,过时效的温度和时间、温轧压下量和再结晶退火温度是通过四因素二水平的正交试验优选出的。取自该超细晶粒薄板的拉伸试样,在505℃和6.66×10~(-4)S~(-1)的初始应变速率条件下拉伸时,获得了0.5的m值和500％的延伸率,显示了良好的超塑性。     

微量添加剂对6063铝合金晶粒细化及力学性能的影响

研究了微量稀土和Al-Ti-B添加剂对6063铝合金的晶粒尺寸和力学性能的影响。结果表明：微量稀土和Al-Ti-B复合作用后的效果更明显，6063铝合金的晶粒得到显著细化，抗拉强度和延仲率得到很大的提高。     

Austenite Grain Refinement and Isothermal Growth Behavior in a Low Carbon Vanadium Microalloyed Steel

The austenite grain refinement through control of the grain growth during reheating process after thermomechanical controlled process(TMCP)in a vanadium microalloyed steel was achieved.The formation of ultra-fine grained austenite was attributed to the high density of austenite nucleation at the ferrite/martensite structure and to the inhibition of austenite growth by(Ti,V)C particles at the relatively low reheating temperature.Corresponding with the precipitation behavior of(Ti,V)C with temperature,the growth behavior of austenite in the vanadium microalloyed steel could be divided into two regions.At lower reheating temperature,austenite grains grew slowly,and ultra-fine grained austenite smaller than 5μm was successfully obtained.By contrast,the austenite grains grew rapidly at high temperature due to the dissolution of(Ti,V)C particles.According to the measured and predicted results of austenite growth kinetics,two models were developed to describe the growth behavior of austenite grains in two different temperature regions,and the apparent activation energy Qappfor grain growth was estimated to be about 115 and 195kJ/mol,respectively.     

钒氮钢中晶粒细化研究

 采用Gleeble 3500热模拟试验机，在相同工艺条件下，对比研究了钒氮钢、钒钢以及碳锰钢的晶粒细化效果。结果表明，钒氮钢的晶粒细化效果最显著，铁素体的晶粒尺寸可达61 μm，这主要与在奥氏体区中析出的V(C，N)有关。奥氏体区析出的V(C，N)，不但可抑制奥氏体晶粒长大，同时还可以作为铁素体的形核核心，诱导晶内铁素体形成，大大增加铁素体形核率，从而提高了相变细化的比率。