J.F. Sun
,
J. Shen
,
Z. Y. Li
,
J. Jia and Q.C. Li National Key Laboratory of Metal Precision Hot Processing
,
Harbin Institute of Technology
,
Harbin 150001
,
China
金属学报(英文版)
Based on the Newtonian heat transfer formulation and classical heterogeneous nucleation theory, a mathematical model has been established to predict the profile of flight velocity, heat transfer coefficient, temperature, solid fraction and cooling rate of atomizing droplets for a superalloy. The results indicated that above parameters change with different droplet size and flight distance. The changing trend as well as the mechanism for the change are described and discussed.
关键词:
spray forming
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null
,
null
,
null
WANG Lei
,
GAO Cai-ru
钢铁研究学报(英文版)
Thermal mechanical control processing (TMCP), the combination of controlled rolling and controlled cooling, provides a powerful means of developing high-strength low alloy (HSLA) steels by intensive microstructural control. In the present investigation, the effects of TMCP parameters, consisting of the finish cooling temperature and the start rolling temperature in non-recrystallization region, on the final microstructure and mechanical properties of Q460q steel have been studied by tensile, Charpy impact tests, optical microscopy. The TMCP parameters for Q460q steel have been optimized by laboratory experiments. And the microstructure and properties of industrial product were coincident with the results of laboratory experiments.
关键词:
;TMCP;mechanical properties;M/A constituent;Q460q steel
LI Zhuang
,
WU Di
,
L Huisheng
钢铁研究学报(英文版)
The effect of thermomechanical processing (TMP) on the mechanical properties of hot rolled multiphase steel was investigated. TMP was conducted using a laboratory hot rolling mill, in which three different kinds of finish rolling deformation degrees and temperatures were applied. The results indicate that polygonal ferrite, granular bainite, and a considerable amount of stabilized retained austenite can be obtained by TMP. The stability of the retained austenite increases with decreasing finish rolling temperature and increasing finish rolling deformation degrees. Ultimate tensile strength (σb), total elongation (δ), and the product of ultimate tensile strength by total elongation (σb·δ) for 50% reduction at finish rolling temperature of 700 ℃ reach maximum values [791 MPa, 36% and 28 476 (MPa·%), respectively].
关键词:
hot rolled multiphase steel;finish rolling deformation degree;finish rolling temperature;retained austenite;mechanical property
ZHANG Zi-Cheng
,
ZHU Fu-xian LI Yan-mei
钢铁研究学报(英文版)
The effect of thermomechanical control processing (TMCP) on microstructure and mechanical properties of Fe-0.2C-1.44Si-1.32Mn hot-rolled TRIP steel was investigated by experiment. Strain-induced transformation and transformation-induced plasticity behavior of retained austenite was discussed. The results show that using multi-pass deformation, reduction per pass of more than critical deformation in austenite recrystallization region, total reduction of more than 58 pct in non-recrystallization region and in high temperature section of two-phase region can result in austenite being refined before γ → α transformation. It is beneficial to get refined ferrite grain in final microstructure. To obtain fine and uniform microstructure and excellent strength-ductility balance, a three-step cooling process (Laminar Cooling－Air Cooling－Ultra-Fast Cooling) after hot rolling was conducted. The ultimate tensile strength and elongation of the testing steel can reach 663 MPa and 41 pct respectively.
关键词:
hot rolled TRIP steel;TRIP effect;retained austenite;transformation-induced plasticity;mechanical properties
材料科学技术（英文）
The hot deformation behavior of a Ti-47Al-2Cr-2Nb-0.2W-0.15B (at.%) titanium aluminide alloy fabricated by pre-alloyed powder metallurgy has been investigated by using the hot compression tests in the temperature range from 950 degrees C to 1300 degrees C and at the strain rates between 10(-3) s(-1) and 10 s(-1). The processing maps have been established to evaluate the optimum hot processing conditions and reveal the instability regions. It is found that the flow stress of the investigated alloy is a strong function of the temperature and the strain rate. The investigated alloy has the optimum hot-working condition at 950 degrees C and 10(-3) s(-1), since the material undergoes dynamic recrystallization to produce a fine-grained microstructure. At 1250 degrees C and 10(-3) s(-1), the alloy exhibits superplastic deformation. At 1300 degrees C and 10(-1) s(-1), the cyclic dynamic recrystallization with high temperature grain coarsening takes place. The material undergoes flow instabilities at lower temperatures and higher strain rates, as predicted by the instability criterion. The processing maps demonstrate that the strain significantly affected the instability regions. The manifestations of the instabilities have been observed in the form of microvoids, wedge cracks, and surface fractures.
关键词:
Titanium aluminide;Powder metallurgy;Hot deformation behavior;Processing map;Dynamic recrystallization;gamma-titanium aluminide;static recrystallization;superplastic;behavior;grain-size;deformation
Gang Wang
材料科学技术（英文）
The hot deformation behavior of a Ti-47Al-2Cr-2Nb-0.2W-0.15B (at.%) titanium aluminide alloy fabricated by pre-alloyed powder metallurgy has been investigated by using the hot compression tests in the temperature range from 950°C to 1300°C and at the strain rates between 10-3 s-1 and 10 s-1. The processing maps have been established to evaluate the optimum hot processing conditions and reveal the instability regions. It is found that the flow stress of the investigated alloy is a strong function of the temperature and the strain rate. The investigated alloy has the optimum hot-working condition at 950°C and 10-3 s-1, since the material undergoes dynamic recrystallization to produce a fine-grained microstructure. At 1250°C and 10-3 s-1, the
alloy exhibits superplastic deformation. At 1300°C and 10-1 s-1, the cyclic dynamic recrystallization with high temperature grain coarsening takes place. The material undergoes flow instabilities at lower temperatures and higher strain rates, as predicted by the instability criterion. The processing maps demonstrate that the strain significantly affected the instability regions. The manifestations of the instabilities have been observed in the form of microvoids, wedge cracks, and surface fractures.
关键词:
Titanium aluminide
ZHAO Xin
,
YANG Xiaoling
,
JING Tianfu
钢铁研究学报(英文版)
The hot deformation characteristics of ductile iron are studied in the temperature range of 973 to 1273K and strain rate range of 0001 to 1 s-1 by using hot compression tests. Processing maps for hot working are developed on the basis of the variations of efficiency of power dissipation with temperature and strain rate. The results reveal that the flow stress of ductile iron is sensitive to strain rate. In the processing map under strain of 07, a domain is centered at 1273 K and 1 s-1, and the maximum efficiency is more than 36%. According to the maps, the zone with the temperature range of 1173 to 1273 K and strain rate range of 01 to 1 s-1 may be considered as the optimum region for hot working.
关键词:
ductile iron; processing map; hot working
Xianfeng PAN
,
Haifeng ZHANG
,
Aimin WANG
,
Bingzhe DING
,
Keqiang QIU
,
Zhuangqi HU
材料科学技术（英文）
This paper reviewed the trend and development of semi-solid metal technique. The processes and mechanisms for producing slurry of SSM and its industrial applications have been summarized and discussed. Discussions on the basic rheological theory are presented for more applications. Further consideration of the development and application of SSM technique is also proposed.
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