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Li A.H.,Shandong University | Zhao J.,Shandong University | Pei Z.Q.,Shandong University | Guo S.G.,Jigang Group Heavy Machinery Co.
Advanced Materials Research | Year: 2011

The failure progression of coated carbide tools in end milling of Inconel 718 superalloy was investigated. Tool wear was measured and failure mechanisms were discussed in the experimental process periodically. The experimental results indicated that the tool failure mechanisms were synergistic interaction among abrasive wear, adhesive wear, and fatigue wear. However, abrasive wear and adhesive wear were the main failure mechanisms at the beginning, fatigue wear prevailed the upper hand around the time when edge chipping appeared, and after edge chipping abrasive wear and adhesive wear dominated until the failure time. In addition, the macroscopic failure of the cutting tools is closely correlated to the nucleation and propagation of the crack under cyclic mechanical and thermal impact forces. Mechanical fatigue wear was the key form of fatigue wear at lower cutting speed, while at higher cutting speed thermal fatigue wear was the dominant fatigue wear. Source


Sun Y.,Anhui University of Technology | Zhu B.,Anhui University of Technology | Dang H.,Anhui University of Technology | Sun H.,Jigang Group Heavy Machinery Co.
Journal of Materials Science | Year: 2011

The flash pyrolysis of polyacrylamide (PAM) in Ar atmosphere was carried out in a tube-type pyrolyzer at 700 °C for 5 min. The volatile products were detected and identified by gas chromatography combined with mass spectrometry (GC/MS). Twenty four kinds of pyrolysis products were identified. In particular, some products, such as acetaldazine and 4-hydroxy-4-methyl-2-pentanone, were the first reported existing in the PAM pyrolysis products, which should play an important role in improving the igniting and combustion performance of Al-H 2O-based propellants. Moreover, the flash pyrolysis residues were analyzed by FTIR. The experimental results show that the pyrolysis products of PAM can be roughly divided into five types. The products of five types promote the igniting and combustion performance of Al-H 2O-based propellants, and the mechanisms of formation of every type are discussed. © 2011 Springer Science+Business Media, LLC. Source


Guo L.,Jigang Group Heavy Machinery Co. | Jiang S.-H.,Jigang Group Heavy Machinery Co.
Zhuzao/Foundry | Year: 2011

The service life of integral casting toothed roll is short and the leakage occurs easily. To solve these problems, a three-stage structure production technology was designed. By selecting suitable material, designing sound casting structure, core box structure and gating system, and adopting reasonable heat treatment process, the problems of leakage and short service life were solved by means of solidification simulation, which can strengthen the quality control of every working step. The experience indicates that the wear resistance and service life of toothed roll were improved. Source


Guo L.,Jigang Group Heavy Machinery Co. | Zhang W.-Z.,Jigang Group Heavy Machinery Co. | Fu X.-L.,Jigang Group Heavy Machinery Co.
Zhuzao/Foundry | Year: 2011

These problems appeared in producing swinging arm casting such as the sand inclusion, off size of casting, difficult cleaning of loose sand in the mould after core setting, easy occurring of flask crush, and the difficult operation of mould closing. The original process was improved, and some measures were adopted including enhancing the working procedure control, designing reasonable outside chill and verifying with simulation software, etc. Finally, the qualified castings were obtained. Source


Li G.,Shandong University | Li G.,Jigang Group Heavy Machinery Co. | Zou Y.,Shandong University | Zou Z.,Shandong University | And 2 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2012

The Nb(C, N) ceramic particulates reinforced Fe-based composite coatings have been successfully synthesized in situ by prior pasting laser cladding on steel 42CrMo. The phase constituents and microstructure of the composite coatings were investigated using X-ray diffraction, and scanning electron micrography. The results indicate that the coatings consist mainly of Fe-Cr fine phases with good resistance to oxidation and corrosion and a few of γ-Fe phases. In-situ synthesized Nb(C, N) particulates are uniformly distributed with blocky morphology in the composite coatings. The wear test shows that these reinforcement particulates improves wear resistance of the coatings significantly. The wear mass loss of the substrate with coating is about one ninth of that of the substrate without coatings. The coatings have better oxidation resistance through 750°C constant temperature oxidation, and the oxide scale mainly consists of NbO1.1 and Cr2O3. The oxidation products of the substrate are Fe2O3, and easy to spall off, resulting in a poor effect in substrate protection. The oxide scale of the coatings is one fifth as thick as that of raw substrate. Source

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