Papers by Keyword: Finish Rolling Temperature

Paper TitlePage

Authors: R. Datta, Sanak Mishra, V. Ramaswamy, Anthony J. DeArdo
193
Authors: Mahesh C. Somani, Jaakko I. Hannula, Antti J. Kaijalainen, Devesh K. Misra, David A. Porter
Abstract: Recent interests in developing novel super-high strength steels have led to extensive research efforts in direct quenching with or without tempering (DQ, DQT) or combined with partitioning (DQP). Both strip and plate products have been targeted for different applications. For boron-microalloyed DQ/DQT steels, the ASTM A255 approach for predicting the hardenability was considered inapplicable. Fresh attempts were made to develop new hardenability models through non-linear regression analysis by dynamically varying both the boron factor and multiplying factors of most elements in the alloy factor. Based on the recent concept of quenching and partitioning (Q&P), a novel processing route comprising thermomechanical rolling followed by direct quenching and partitioning (TMR-DQP) has been established for the development of ultra-high strength structural steels with yield strengths ≈1100 MPa combined with good uniform and total elongations and impact toughness. Examples of recent advances made in DQ processing and associated challenges, such as those related to the bendability of low carbon martensitic-bainitic steels and influence of boron on the toughness of Nb-bearing martensitic steels are presented.
1819
Authors: Mahesh C. Somani, David A. Porter, L. Pentti Karjalainen, R.D.K. Misra
Abstract: This study presents the use of physical and laboratory rolling simulations for the development of a novel direct quenching and partitioning (DQ&P) process for the development of tough ductile ultra-high strength structural steels with yield strengths ~1100 MPa and reasonable ductility and toughness. Suitable compositions were designed based on high silicon and/or aluminium content. The DQ&P parameters were established with the aid of physical simulation on a Gleeble simulator. Two types of dilatation tests were carried out: with or without prior straining in the no-recrystallization regime to establish the influence of controlled deformation on subsequent transformation structures and properties. Based on dilatation results, simulated rolling trials were conducted on a laboratory rolling mill and the rolled samples were direct quenched in water to the desired quench stop temperatures followed by partitioning in a furnace held at this temperature. Detailed microstructural examination confirmed that the desired martensite-austenite microstructures were achieved. Besides high strengths, the ductility (including uniform elongation) and impact toughness were quite improved in comparison to that of a direct quenched carbon steel in the same strength class.
83
Authors: M. Salari, A. Akbarzadeh, M.M. Saffari
Abstract: Optimized conditions of hot and cold rolling followed by annealing can result in a balance between recrystallization and rolling textures in order to reduce the planar anisotropy of brass sheets. In this work, the effect of finish rolling temperature, cold reduction and annealing temperature on texture development has been investigated. It is shown that uniform deformation at higher finishing temperature is responsible of formation of a severe Cube and G texture components. In contrast, mechanical twinnings are widely formed at low finishing temperatures. There is also a direct relation between the intensity of Cube component and the amount of cold reduction.
755
Authors: Kee Hyun Kim, Nong Moon Hwang, Byeong Joo Lee, Jong Kyu Yoon
Abstract: Mechanical properties of line pipe steels used in the deep sea or in the severe cold climate depend on alloying elements and manufacturing processes and many efforts have been made to enhance the properties of the line pipe steels. In this study, for systematic approaches to the process design of line pipe steels, its phase diagram was calculated using a Thermo-CalcTM program. The calculations indicated that A3 is around 840oC. Setting the FRT(Finish Rolling Temperature) above A3 appears to be critical to the increase of strength and toughness of line pipe steels by increasing the amounts of acicular ferrite and at the same time by decreasing the precipitation of proeutectoid ferrite. In the case of the FRT below A3, relatively large amounts of proeutectoid ferrite are precipitated from the matrix with the carbon contents of the austenite phase around ferrite being enriched.
89
Authors: Mahesh C. Somani, L. Pentti Karjalainen, David A. Porter, R.D.K. Misra
Abstract: An experimental steel containing in weight % 0.2C-2.0Mn-1.5Si-0.6Cr has been laboratory hot rolled, direct quenched into the Ms - Mf range and partitioning annealed in order to explore new possibilities for making 1100 MPa yield strength structural steels with better combinations of strength, ductility and impact toughness. Two austenite states prior to quenching were investigated: recrystallized and strained. Gleeble simulations were used to determine appropriate cooling rates and cooling stop temperatures for obtaining martensite fractions in the range 70-90%. Desired martensite - austenite microstructures were achieved, and ductility and impact toughness were better than those obtained via the simple direct quenching of a lower carbon steel in the same strength class.
2824
Authors: Mahesh C. Somani, David A. Porter, L. Pentti Karjalainen, Pasi Suikkanen, R.D.K. Misra
Abstract: Based on the recent concept of quenching and partitioning (Q&P), a novel TMR-DQP (thermomechanical rolling followed by direct quenching and partitioning) processing route has been established for the development of ultra-high strength structural steels with yield strengths ≈1100 MPa combined with good uniform and total elongations and impact toughness. Suitable compositions were designed based on high silicon and/or aluminium contents with or without small additions of Nb, Mo or Ni. The DQP parameters were established with the aid of physical simulation on a Gleeble simulator. Finally, the TMR-DQP processing route was designed for trials on a laboratory rolling mill. Metallographic studies showed that the desired martensite-austenite microstructures were achieved thus providing the targeted mechanical properties. The advantage of strained austenite in refining the martensite packets/blocks was clearly evident. No adverse effect of prolonged partitioning simulating the coiling stage has been noticed suggesting new possibilities for strip and plate products. Promising results in respect of microstructures and mechanical properties indicate that there are possibilities for developing tough ductile structural steels through the TMR-DQP route.
1009
Authors: Fei Gao, Wei Na Zhang, Zhi Bo Zhang, Zhen Yu Liu, Guo Dong Wang
Abstract: The influence of finish rolling temperature on the precipitates and Lüders elongation in ultra purified ferritic stainless steels stabilized with Ti and V has been investigated, in which the hot rolled bands were produced by conventional rolling process and the finish rolling at relatively low temperatures. It was shown that finish rolling at relatively low temperatures promoted the formation of a large number of fine MC precipitates, which were denser in dispersion and finer in size than those formed in conventional rolling process by strain-induced precipitation, and consequently scavenging of interstitial atoms in solid solution, indicating that the finish rolling at relatively low temperatures can be the effective way to significantly reduced Lüders elongation for the final sheets. These results have been confirmed by the internal friction measurements.
16
Authors: Zhi Min Zhang, Feng Qin Wang, Fei Li, Shu Zhi Wang, Xiao Jiang
Abstract: Coiling temperature, finish rolling temperature and running speed of ZSAC1 strip during U-type cooling and number of valves which had been turned on were analyzed in order to find out the reason of low coiling temperature at tail of ZSAC1 strip in U-type cooling process. Results of research showed that running speed of strip and finish rolling temperature were main factors affecting accuracy of coiling temperature. Coiling temperature decreased with the increase of running speed of strip. Coiling temperature fluctuation would occur at the same part of strip when finish rolling temperature increased or decreased. Holding rolling speed and rolling temperature of strip stably can improve accuracy of coiling temperature during downstream U-type cooling.
290
Authors: Si Yue Chen, Jing Xu, Xin Zhang, Yi Tao Yang
Abstract: In this paper, the influence of finish rolling temperature during hot rolling on microstructure and mechanical properties of ferritic stainless steel containing vanadium was investigated. It showed that with the rolling temperature increasing, the tensile strength and hardness value fell down, while the value of ductility rising and less precipitates appearing. If the finish rolling temperature was set too high, the grain would get coarsened and the α-fiber get strengthened, which had an adverse effect on the formability and wrinkle resistance of the production sheet. 850°C was a reasonable finish rolling temperature.
176
Showing 1 to 10 of 10 Paper Titles