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Wang M.,Kunming University of Science and Technology | Wang M.,Control Iron and Steel Research Institute, China | Ma D.,Control Iron and Steel Research Institute, China | Liu Z.,Fushun Special Steel Co. | And 3 more authors.
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2014

Mandrel is an important tool for thermal deformation of the seamless steel tube rolling unit. It requires high heat resistance and toughness due to its application in the harsh environment. H13 steel is commonly used as mandrel materials with excellent comprehensive performance. It is reported that addition of carbide-forming elements, such as Nb, Ti, or Zr, especially the Nb element, can break the dendritic microstructure and refine the cast structure of H13 steel. In addition, Nb can act as a strong carbide-forming element to favor the formation of MC carbide. This stable carbide has low solubility and does not dissolve in austenite even at high temperature, and hence fines austenite grain by pinning effect of carbide on grain boundary. As the stable NbC has stronger ability to improve the fatigue resistance and abrasion resistance than Mo6C and VC, the mandrel steel can be produced by the method of Nb addition. It has been reported that the addition of Nb in H13 can successfully increase heat resistance. Nb element dissolves into the matrix after quenching and tempering, and precipitates in the form of NbC after heat preservation for a long time, and eventually improves the resistance of material to temper softening. However, it has not been widely applied in the production because the primary carbides of NbC can seriously deterio- rate toughness of steel. The purpose of the work is to analyze the effect of addition of 0.06%Nb (mass fraction) on segregation, primary carbides and toughness of large size H13 mandrel steel. The different segregation, primary carbides, structure between large size H13 and H13-Nb mandrel were investigated by employing methods of OM, SEM, EDS and EBSD, and the mechanical properties including the hardness and impact toughness were measured at room temperature. The results show that addition of 0.06%Nb aggravates segregation compared with H13. Nb increases the precipitation temperature of MC-primary carbides, and changes the type of MC-primary carbides from mainly VC to mainly (Nb, V)C which easily induces gravitational segregation of H13-Nb. The severe segregation leads to unfavorable structure of the large and nonhomogeneous effective grain size (EGS) of annealed H13-Nb, and the primary carbides do not decrease or change significantly after quenching and tempering. In the impact test, the zone of the chain-shaped carbides gathering is prone to cracking and generates horizontal stripes, resulting in low toughness. © Copyright.


Luo Z.,Northeastern University China | Liu H.,Northeastern University China | Wang F.,Northeastern University China | Xu L.,Fushun Special Steel Co.
International Journal of Modelling, Identification and Control | Year: 2010

The current development of human-simulated intelligent control (HSIC) is introduced and the basic concepts, ideology and features are summarised. Then, examples are taken for the prototype algorithm of HSIC; the static characteristics, dynamic characteristics and stability of HSIC are analysed. The basic design steps of HSIC are further cleared. Finally, the application of HSIC in the trajectory tracking control for robot system is studied. In fact, HSIC is for choosing the appropriate control strategy according to the sign of the characteristic variables of the control system. The experimental results show that the HSIC method improves the control precision greatly. Copyright © 2010 Inderscience Enterprises Ltd.


Zhang H.,Harbin Institute of Technology | Zhang K.,Harbin Institute of Technology | Zhou H.,Harbin Institute of Technology | Lu Z.,Harbin Institute of Technology | And 2 more authors.
Materials and Design | Year: 2015

The hot deformation behavior of a nickel-based superalloy was investigated by means of isothermal compression tests in the strain rate range of 0.001-10 s-1 at 1110°C. Transmission electron microscope (TEM) and electron backscatter diffraction (EBSD) technique were used to study the effect of strain rate on the microstructure evolution of the alloy during hot deformation. The results revealed that the dynamic recrystallization (DRX) process was stimulated at high strain rates (ε˙≥5s-1) due to the high dislocation density and adiabatic temperature rise. Meanwhile, high nucleation of DRX and low grain growth led to the fine DRX grains. In the strain rate rage of 0.001-1 s-1, the volume fraction of DRX grains increased with the decreasing strain rate, and the grain growth gradually governed the DRX process. Moreover, the strain rate has an important effect on DDRX and CDRX during hot deformation. On the other hand, particular attention was also paid to the evolution of twin boundaries during hot deformation. It was found that there was a lower fraction of σ3 boundaries at the intermediate strain rate of 1s-1, while the fractions of σ3 boundaries were much higher at both the lower strain rates (ε˙≤0.1 s-1) and higher strain rates (ε≥5 s-1). © 2015 Elsevier Ltd.


Wang Y.,Fushun Special Steel Co. | Zhao M.,Fushun Special Steel Co. | Xie L.,Fushun Special Steel Co. | Zhu B.,Fushun Special Steel Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Abnormal microstructure of TC11 alloy large-sized bars was analyzed. The results show that the abnormal weave microstructure is composed of lamellar α and β, the microhardness of the abnormal microstructure is higher than that of the matrix, the content of Mo is higher than that of the matrix, while the content of Al is less. The abnormal microstructure is β fleck that resulted from the microinhomogeneity of chemical composition in the ingot due to the rising of temperature in the course of finish forging. © 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.


Li Z.-X.,Northeastern University China | Li C.-S.,Northeastern University China | Zhang J.,Northeastern University China | Li B.-Z.,Northeastern University China | Pang X.-D.,Fushun Special Steel Co.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2016

The effect of final rolling temperature and cooling process on the microstructure of 1.0C-1.5Cr bearing steel was studied, and the relationship between the microstructure parameters and subsequent spheroidization annealing was analyzed. The results indicate that the increase of water-cooling rate after hot rolling and the decrease of final cooling temperature are beneficial to reducing both the pearlite interlamellar spacing and pearlite colony size. Prior austenite grain size can be reduced by decreasing the final rolling temperature and increasing the water-cooling rate. When the final rolling temperature was controlled around 1103 K (830 °C), the subsequent cooling rate was set to 10 K/s and final cooling temperature was 953 K (680 °C), the precipitation of grain boundary cementite was suppressed effectively and lots of rod-like cementite particles were observed in the microstructure. Interrupted quenching was employed to study the dissolution behavior of cementite during the austenitizing at 1073 K (800 °C). The decrease of both pearlite interlamellar spacing and pearlite colony size could facilitate the initial dissolution and fragmentation of cementite lamellae, which could shorten the spheroidization time. The fragmentation of grain boundary cementite tends to form large-size undissolved cementite particles. With the increase of austenitizing time from 20 to 300 minutes, mean diameter of undissolved cementite particles increases, indicating the cementite particle coarsening and cementite dissolution occuring simultaneously. Mean diameter of cementite particles in the final spheroidized microstructure is proportional to the mean diameter of undissolved cementite particles formed during partial austenitizing. © 2016 The Minerals, Metals & Materials Society and ASM International


Wang Y.,Fushun Special Steel Co. | Dong J.,Fushun Special Steel Co. | Wang D.,Fushun Special Steel Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

Effects of heat treatment process on microstructure and mechanical properties of TC18 alloy forged piece were investigated. The results show that with the annealing temperature rising, the percentage of equiaxed primary α phase decreases and grain size increases, meanwhile the pescentage of lamellar secondary α phase increases and its grain size gradually grows up which leads to higher strength but lower plasticity for the TC18 alloy. Secondary α phase coarsens and dispersion degree declines with the increase of low-stage annealing temperature, the strength decreases but the plasticity increases. The microstructure and mechanical properties are preferable and meet standard specification when treated by 830°C×2 h, furnace cooled+750°C×2 h, air cooled+540°C×6 h, air cooled.


Zhang H.,Harbin Institute of Technology | Zhang K.,Harbin Institute of Technology | Jiang S.,Harbin Institute of Technology | Zhou H.,Harbin Institute of Technology | And 2 more authors.
Journal of Alloys and Compounds | Year: 2015

The hot deformation behavior of a γ′-hardened nickel-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1010-1210 °C with a strain rate of 0.1 s-1. The electron backscatter diffraction (EBSD) technique and transmission electron microscope (TEM) were employed to investigate the effect of deformation temperature and strain on the microstructure evolution and nucleation mechanisms of dynamic recrystallization (DRX). Microstructure observations revealed that the size and volume fraction of DRX grains increased with the increasing temperature. A power exponent relationship was obtained between the stable DRX grain size and the peak stress. Additionally, it was found that the effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature, and DDRX was the operating nucleation mechanism of DRX at higher deformation temperature. On the other hand, the effect of DDRX became stronger with the increasing strain, and CDRX can only be considered as an assistant nucleation mechanism of DRX at the later stage of deformation for the alloy deformed at 1160 °C. Nucleation of DRX can also be activated by the twinning formation. Hence, particular attention was also paid to the evolution of twin boundaries during hot deformation. © 2014 Elsevier B.V.


Bao W.,Fushun Special Steel Co. | Liu G.,Fushun Special Steel Co. | Yang J.,Fushun Special Steel Co. | Guo Q.,Fushun Special Steel Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

Effect of solution and aging process on microstructure and properties of 45Cr14Ni14W2Mo steel was investigated. The experimental results show that the 45Cr14Ni14W2Mo steel can obtain preferable mechanical properties after solution at 1170℃ for 60 min and age at 760℃ for 5 h which can meet the standard requirements of valve steel and superalloy bars for internal combustion engines. © 2016, Editorial Office of "Jinshu Rechuli". All right reserved.


Zhang H.,Harbin Institute of Technology | Zhang K.,Harbin Institute of Technology | Lu Z.,Harbin Institute of Technology | Zhao C.,Fushun special steel Co. | Yang X.,Fushun special steel Co.
Materials Science and Engineering A | Year: 2014

The hot deformation behavior of a γ'-hardened nickel-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1010-1160°C and strain rate range of 0.001-1s-1. The results show that the hot activation energy of the alloy is about 427.626kJ/mol. On the basis of experimental data, processing maps were developed by utilizing the principles of the dynamic materials model (DMM). The processing maps exhibit one domain with high efficiency of power dissipation. At the strain of 0.6, the domain occurs in the temperature range of 1105-1160°C and strain rate range of 0.02-0.25s-1 with a peak efficiency of about 42.2%. Microstructure observations reveal that full dynamic recrystallization (DRX) occurred in the domain. In the processing maps, the curvature changes of the isoefficiency contours occur in the temperature range of 1080-1090°C, which is at the dissolution temperature of γ' phase in the alloy. Moreover, it can be found that the strain has an effect on the efficiency of power dissipation. The efficiency value increases with increasing strain in the high strain rate domain (0.1-1s-1), while the efficiency value decreases with increasing strain in the high temperature (1080-1160°C) and low strain rate (0.001-0.01s-1) domain. The flow instability is predicted to occur in the high strain rate domain, which is manifested as adiabatic shear bands. © 2014 Elsevier B.V.


Wang C.-X.,Control Iron and Steel Research Institute, China | Liu X.-M.,Control Iron and Steel Research Institute, China | Tian Z.-L.,Control Iron and Steel Research Institute, China | Wang R.,FuShun Special Steel Co. | Li J.-X.,FuShun Special Steel Co.
Hangkong Cailiao Xuebao/Journal of Aeronautical Materials | Year: 2011

The hot compression deformation behaviors of secondary hardening ultra-high strength 23Co14Ni12Cr3MoE steel with high strength and toughness were investigated by use of Gleeble-3800 simulator at the temperature range of 1123K to 1423K and at the strain rate of 0.5~10s -1. The corresponding flow curves were determined and hot deformed microstructures were observed. The results show that the flow stress and peak strain increase with increasing strain rate or decreasing deformation temperature. At true strain 0.8 and the strain rate of 0.5~10s -1, the temperature of full dynamic recrystallization increase with the strain rate rising. When the strain rate is 10s -1, the deformation temperature is beyond 1373K, the full dynamic recrystallization is occurred. The hot deformation activation energy Q of steel is 421.6kJ/mol, and the hot deformation equation is derived based on the experiments.

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