Long J.,State Key Laboratory of Cemented Carbide |
Zhang Z.,Zhuzhou Cemented Carbide Group Corporation Ltd. |
Xu T.,Zhuzhou Cemented Carbide Group Corporation Ltd. |
Lu B.,Zhuzhou Cemented Carbide Group Corporation Ltd.
International Journal of Refractory Metals and Hard Materials | Year: 2013
In this paper, the effect of the carbon contents on the microstructure, mechanical properties and fracture behavior of WC-40 vol.% Ni3Al composites prepared by conventional powder metallurgy was studied. Microstructure examinations of WC-40 vol.% Ni3Al specimens indicated that the WC grain is round and fine compared with faceted and large WC grain of WC-Co composites. With increasing carbon contents, the WC morphology of WC-40 vol.% Ni3Al composites is similar and the size of WC grain is approximate and the distribution of binder phase becomes relatively uniform. Furthermore, composition analysis of binder phase showed that, with the increase of carbon content, the solubility of W in Ni3Al reduced slightly. The ~ 9 wt.% solubility of W in Ni3Al is much lower compared with ~ 22.4 wt.% of WC-40 vol.% Co composites. The hardness and transverse rupture strength of WC-40 vol.% Ni3Al composites decrease with increasing carbon contents slightly. WC-40 vol.% Ni3Al composites present higher hardness and lower transverse rupture strength than that of WC-40 vol.% Co composites. With increasing carbon contents, the fracture behavior of the WC-40 vol.% Ni3Al composites is affected greatly and the fracture mode changes from transgranular fracture towards intergranular fracture. © 2013 Elsevier Ltd.
Xiao S.,Hunan University |
Wang L.,Zhuzhou Cemented Carbide Group Corporation Ltd |
Chen Z.C.,Zhuzhou Cemented Carbide Group Corporation Ltd |
Wang S.,Concordia University at Montréal |
Tan A.,Concordia University at Montréal
Journal of Manufacturing Science and Engineering, Transactions of the ASME | Year: 2013
Solid carbide cylindrical end-mills are widely used in machining, and their helical flutes are crucial to their cutting performance. In industry, the flute is simply defined with four key parameters: the helical angle, the radial rake angle, the fluting angle, and the core radius, which are specified in an end-mill design. The flute shape is not fully defined, while it is often generated by a 1A1 or 1V1 diamond wheel in 21/2-axis computer numerically controlled (CNC) grinding. Unfortunately, the two simple wheels cannot make largely different flute shapes, preventing further improvement of the end-mills. Although no research result on how the flute geometry affects the end-mill cutting attribute has come into public yet, it is now necessary to employ more complicated wheels to grind flutes with the specified parameter values but much different flute shapes. For this purpose, the 4Y1 diamond wheel is employed in this work. However, the commercial tool grinding software cannot determine the dimensions and the set-up angle for the 4Y1 wheel. To address this problem, a new mathematical model of the flute parameters in terms of the dimensions and the setup angle of the 4Y1 wheel is formulated, thus, the 4Y1 wheel can be used in flute grinding. This work lays a foundation of using complex wheels to grind flutes with more shapes in order to improve the end-mill's cutting ability. Copyright © 2013 by ASME.
Gu L.,Central South University |
Huang J.,Central South University |
Huang J.,Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education |
Xie C.,Zhuzhou Cemented Carbide Group Co.
International Journal of Refractory Metals and Hard Materials | Year: 2014
Effects of carbon content on microstructure and properties of WC-20Co cemented carbides with carbon content from 4.45% to 5.25% prepared by sinter-HIP were analyzed by X-ray diffractometry (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), Rockwell hardness analysis, cobalt magnetic performance analysis, bending strength analysis and so on. The results show that carbon content plays a significant role in the phase composition and microstructure, WC grain size and shape, W solubility of the binder, and mechanical properties of cemented carbides. In the field of research, with increasing carbon content, the WC mean grain size increases and morphology characteristic of WC grains tends to show truncated trigonal prim shape. And carbon content also influences W solubility, so that in carbon-rich cemented carbides the binder dissolves about 4 mass% tungsten and in carbon-deficient cemented carbides up to 20 mass%. The density and Rockwell hardness of alloys decrease with increasing carbon content. On the contrary, the cobalt magnetic performance of alloys increases and the extent of variation gets smaller and smaller. The bending strength of alloys increases then substantially decreases with increasing carbon content and appears maximum in the two-phase region. © 2013 Elsevier Ltd.
Meng X.W.,Zhuzhou Cemented Carbide Group Corporation Ltd
Advanced Materials Research | Year: 2014
A new kind of binder was developed in extrusion molding. It included four ingredients:ethylene glycol acetate (60%~85% (mass/mass, as follows)), ethyl cellulose (10%~30%), ethylene glycol polyoxyethylene ether (5%~10%), polyethylene glycol stearate (0.8%~3%). The components of binder were compatible with thermodynamic conditions, so the binder was well-distributed in molecule level. The new binder is actual nontoxic, secure and environmentally friendly. The forming property of the binder is so excellent that it can load 54% ~ 56% (vol. /vol.) cemented carbidepowders. The rods produced by this new binder provide high strength, stable performance, homogeneous microstructure. © (2014) Trans Tech Publications, Switzerland.
Wei X.,Central South University |
Wei X.,Zhuzhou Cemented Carbide Group Co. |
Zheng Z.,Central South University |
She L.,Central South University |
And 2 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2010
The effect of Mg and Zn additions on the microstructure evolution and mechanical properties of an Al-Cu-Li alloy was studied by transmission electron microscopy and tensile testing. Results show that additions of Mg and Zn can accelerate the precipitation of δ' phase nucleation and inhibit its growth, so the δ' phase becomes finer and more dispersive. In the under-aging condition, a lot of GP zones are formed in the alloy containing Mg and Zn. The alloy only containing Mg also has many GP zones. But no GP zone is found in the alloy only containing Zn, while only a few coarse θ' is found. The above results reveal that Mg promotes the formation of GP zones while the single role of Zn is not significant; Zn has a better effect when it acts with Mg together. As the aging proceeding, GP zones in the alloy containing Mg and Zn transforms into θ'/θ″ phase and plenty of θ'/θ″ phases are formed in the alloy only containing Mg, but θ' phase dose not change obviously in the alloy only containing Zn. It indicates that Mg is the key element to accelerate θ'/θ″ phase formation, and Zn can promote the formation only with Mg.
Lin G.,University of Science and Technology Beijing |
Zhang Z.,Zhuzhou Cemented Carbide Group Corporation Ltd |
Wang M.,Zhuzhou Cemented Carbide Group Corporation Ltd |
Zhu S.,University of Science and Technology Beijing
Advanced Materials Research | Year: 2013
This paper presents the research on the influence of carburizing and heat treatment on the properties and microstructure of a new medium carbon alloy steel Fe-0.39C-0.99Si -0.37Mn -5.06Cr-1.21Mo-0.75V (wt.%) used for disk cutter ring. The carburized case has secondary cementite besides those appeared in core such as pearlite and some carbides of Cr, Mo and V. Microstructure of the case is coarse and there are more and larger carbide particles than in core. After quenching and tempering, the carburized case and the core transformed into the microstructure comprised mostly of troostite and fully precipitated tiny carbide particles of Cr, Mo and V. The grains in the carburized case are still larger and the quantity of carbide precipitations including cementite is larger compared with that in the core. Finally, the case depth of about 1mm can be obtained; the surface hardness is above 60HRC; the core hardness is above 55HRC; and the impact toughness reaches 16.9 kJ/cm2. © (2013) Trans Tech Publications, Switzerland.
Meng X.,Zhuzhou Cemented Carbide Group Corporation Ltd.
Advanced Materials Research | Year: 2011
The advantages and disadvantages between the pressing binder of hardmetal in existence are analyzed. A new type of binder named QSD is introduced and a series of properties are studied. The experiments show that QSD has been tested to dissolve in alcohol. The materials of hardmetal are milled in alcohol mixed with QSD, achieving a molecule dispersing slurry. The slurry adapts to spray drying with low viscidity. The mixture of the hardmetal prepared by QSD is fine, and soft with good flowability. They are capable of pressing complex form of products that couldn't be formed with PEG, paraffin wax binder by comparing the experiments. The compacting force has reduced 20% compared to PEG. The pressing products are effectively less vices of delamination and crack due to the low brittleness and high weight of compact. The products made by QSD fit continuous sintering and there are few remainder carbon in the sintered products. Microstructural observation reveals that the Co particle distributes homogeneously in the WC particle with the pressing binder QSD. So QSD is one kind of considerably ideal cemented carbide binder that combines the advantages of PEG, SBS.
Xie C.-H.,Zhuzhou Cemented Carbide Group Corporation |
Huang J.-W.,Central South University |
Tang Y.-F.,Central South University |
Gu L.-N.,Central South University
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2015
The effects of deep cryogenic treatment on the microstructure and properties of WC-11Co cemented carbides with various carbon contents were investigated. The results show that after deep cryogenic treatment, WC grains are refined into triangular prism with sound edges via the process of spheroidization, but WC grain size has no evident change compared with that of untreated alloys. The phase transformation of Co phase from α-Co (FCC) to ε-Co (HCP) is observed in the cryogenically treated alloys, which is attributed to the decrease of W solubility in the binder (Co). Deep cryogenic treatment enhances the hardness and bending strength of the alloys, while it has no significant effects on the density and cobalt magnetic performance. © 2015 The Nonferrous Metals Society of China.
Zhuzhou Cemented Carbide Group Corporation Ltd. | Date: 2014-03-26
The present disclosure discloses a pre-tightening locking device (100) for retaining a component on a shaft, comprising: a backing ring (1) having a first end face (11) and an opposite second end face (12), wherein the backing ring is mounted on the shaft with the first end face (11) thereof closely engaging with the component to be retained; a pre-tightening nut (3) threadedly coupled on the shaft, wherein one end of the pre-tightening nut engages with the second end face (12) of the backing ring (1); a hydraulic nut (4) arranged outside of the pre-tightening nut (3) through threads, wherein an annular piston (5) of the hydraulic nut (4) is capable of exerting an acting force on the backing ring (1) under fluid pressure so as to form an interval between the backing ring (1) and the pre-tightening nut (3); and a filling member for filling the interval. A filling member is provided for filling the interval so that a pre-tightening force can be maintained, which ensures that the component on the shaft is closely retained. Under this condition, the hydraulic nut can be removed, whereby the cost is significantly reduced.
ZHUZHOU CEMENTED CARBIDE GROUP Corporation | Date: 2016-04-15
Machine parts, namely, drilling heads, blades, blade holders; tools, namely, metalworking machine tools; holding devices for machine tools, namely, machine tool holders.