Abstract: A new model to predict the structure evolution of 30Cr2Ni4MoV steel is proposed based on the dislocation density in this research. Hot compression of 30Cr2Ni4MoV steel is carried out on Gleeble 1500 at different temperatures from 1233 K to 1473 K with a strain rate of 0.01 s-1 and the deformed samples are immediately quenched by water to frozen the austenite structure. The recrystallization kinetics model of 30Cr2Ni4MoV steel is successfully established by inverse analysis of the flow curve based on the relation between flow stress and dislocation density. In order to validate the proposed model, comparison between the predicted values and experimental values obtained by metallographic analysis is implemented. It is shown that the predicted results agree with the experimental results well.
Abstract: This paper presents how to derive Airy stress function to obtain the thermal stresses in a tungsten-steel functionally graded solid cylinder with fixed ends in elastic region. Once Airy stress function is derived, the thermal stresses can be found due to the related equations. There is uniform heat generation inside the tungsten-steel functionally graded solid cylinder. Material properties of the functionally graded cylinder (FGC) are assumed to vary radially according to a parabolic form and assumed to be independent of the temperature. These properties are yield strength, modulus of elasticity, coefficient of thermal conduction and coefficient of thermal expansion (CTE). Poisson’s ratio is assumed to be constant as an average value between tungsten’s and steel’s. Airy stress function is derived in terms of these properties to characterize the FGC entirely.
Abstract: In view of the fact that construction of modern buildings tends to use a high ratio of iron materials, this study aimed to obtain the ratio of components of steel’s microstructure under different test conditions by heating a A36 steel sheet commonly used in buildings, and applying metallographic replication testing. When the steel sheet was heated above 800°C and then rapidly cooled by water, the ratio of components of the structure were changed dramatically: components such as pearlite disappeared, ferrite was reduced from 90% to a low of 20%, bainite was increased to a maximum of 35%, and martensite was increased to a maximum of 45%. Since the substantial increase of martensite phase in this study led the microstructure of iron material to become thinned out and scattered, the ductility of such material was significantly reduced accordingly, thereby making the steel sheet easily broken. This study expected to provide the test findings of the mechanical behavior and metallographic structure of steel, after being heated to a high temperature and then naturally cooled, to other relevant units of construction engineering to serve as reference for their evaluation of non-destructive testing of steel structures.
Abstract: This study aims to assess the solidification shrinkage and expansion during the solidification of cast irons. The solidification shrinkage and expansion in cast irons are due to the formation of austenite and graphite respectively. In this study, the linear displacement method was used to observe the solidification event combined with the cooling curve analysis. It was found that the cooling and displacement curves show good correlations in time of events during solidification. The displacement due to graphite expansion increased with the carbon equivalent. The linear expansion of 0.2 to 1.9 mm was observed for the carbon equivalents ranged from 3.7 to 4.5. On the other hand, the displacement due to the austenite shrinkage was found to decrease with increasing carbon equivalents.
Abstract: In turning hardened steel, polycrystalline cubic boron nitride (cBN) compacts are widely used, due to their high hardness and high thermal conductivity. However, in milling hardened steel, fracture of cBN cutting tools readily occurs because they have poor fracture toughness. Therefore, coated cemented carbide tools, which have good fracture toughness and wear resistance, are generally and widely used. In this study, hardened steel (ASTM D2, JIS SKD11, 60HRC) was milled with three physical vapor deposition coated cemented carbide end mill cutters in order to determine effective tool materials for milling hardened steel. The coating films used were two types of aluminum/chromium/tungsten/silicon-based-coating films and (Ti,Al)N-coating film. The two types of aluminum/chromium/tungsten/silicon-based-coating films are a new type of coating film, and the Type I and Type II coating film was a two-layered and multi-layered structure, respectively. The following results were obtained: (1) In milling hardened steel at a cutting speed of 2.5 m/s, Type II coating film was the best coating material among the three types of coated film. Type I coating film was superior to (Ti,Al)N-coating film. (2) The critical scratch load of both Type I and Type II of over 130 N became larger than that of the (Ti,Al)N-coating film of 65 N. (3) The multi-layered structure is expected to improve the tool life.
Abstract: Diamondand PCBN are extra-hard materials. There are several grades in the PCD andPCBN groups. Comprehensive Review of Super hard materials such as diamond cutting tools, high-speed machining PCBN tool and performance, the type of domestic and international manufacturing and research status . Elaborate on three high-speed machining with a diamond cutter nature and characteristics of the domestic and foreign manufacturing enterprise status, as well as polycrystalline cubic boron nitride tool features and applications. The isotropic synthetic graphite high-speed processing of diamond tool applications, engine block, cylinder heads high-speed milling PCBN cutting tool applications, aerospace application example to illustrate the advantages of hard material tool in high-speed machining of titanium alloys in high speed turning PCBN tools. Hard material tool to provide guidance and support for the selection of high-speed processing manufacturing enterprises.
Abstract: In this research study the fabricated of hydrophobic of SiO2 nanoparticles was modified with tetraethylorthosilicate (TEOS), poly-(dimethylsiloxane) (PDMS) and methyltriethoxysilane (MTES) by using a sol-gel method. The effects of precursors, coating techniques and curing conditions were investigated. A water contact angle (WCA) measurement done using a sessile drop method with an optical contact measuring apparatus. Morphologies of the hydrophobic films were depicted using scanning electron microscopy (SEM). All data were analyzed using Design Expert® software. Results shown that a morphology of hydrophobic films had nanoroughness as evidenced by high contact angle. The largest predicted WCA of these is 150.306 degrees, which will be obtained with a TEOS:SiO2:PDMS:MTES ratio equal to 7.00:3.374:2.75:3.00 wt.% respectively. It is coated using a dipping technique and oven cured at 400°C.
Abstract: The article studies deformation behavior in friction-cyclic loading of composite surface layers, that were made of materials with shape memory effect (SME). We have demonstrated that a multi-layer composite surface layer (Ni - TiNiHf - TiNi), which was formed by the high-speed flame spraying of mechanically activated powders with subsequent thermomechanical processing, enhances the wear resistance and fatigue strength of products. This is due to the special properties of materials with shape memory.
Abstract: Ferrite is well known as a beneficial phase that can prevent hot cracking phenomena and act as strengthening phase in austenitic stainless steel weld metal. This paper investigated mechanical and corrosion behaviour of austenitic weld metal grade 308L which deposited by SMA (Shielded Metal Arc) method with various ferrite content. Several tests such as tensile at room temperature, charpy impact V-notch and lateral expansion at cryogenic temperature-196°C were conducted to observe mechanical behaviour. Electrochemical testings such as Cyclic Polarization method and Electrochemical Impedance Spectroscopy (EIS) were also performed. Controlling weld metal 308L with ferrite number (FN) 2 and manganese content about 1.53 % could achieve excellent toughness and hot cracking resistance as well as improved pitting corrosion resistance for cryogenic purpose.
Abstract: Bioethanol is a clean and sustainable fuel; on the contrary, the addition of bioethanol to gasoline normally creates corrosion on automobile fuel system materials. In this study, corrosion characteristics of low carbon steel normally encountered in gasoline engine fuel system with bioethanol fuel was investigated. Static immersion tests in different fuel blends E0 (gasoline), E10 and E85 were carried out at room temperature for 1320 h. The mechanical, physical and chemical properties of low carbon steel before and after immersion tests were investigated. Moreover, the physical and chemical properties of fuel blends before and after immersion tests were investigated. The results revealed that the usage of E10 blend is considered feasible for gasoline engines in terms of materials compatibility compared to E85.