ZHANG Hua-wei
,
LIU Li-zhong
,
HU Ping
,
LIU Xiang-hua
钢铁研究学报(英文版)
In order to grasp the springback rule of TRB (tailor rolled blank) parts after forming, the springback behavior of TRB was investigated by integrating such three means as theoretical research, numerical simulation and stamping experiments. Fundamental theories of springback were analyzed. The stamping and springback processes of annealed 1.2/2.0 mm TRB, 1.2 mm and 2.0 mm plates for U-channel were simulated, and the simulation results were compared with the experiments. The results indicate that the springback of TRB falls in between those of the 1.2 mm and 2.0 mm plates. It is desirable for the TRB U-channel to have die clearance of 1.1 times maximum blank thickness and friction coefficient of about 0.12, and longer thickness transition zone is preferable. The simulation data demonstrate reasonably good agreement with the experiments.
关键词:
tailor rolled blank
,
U-channel
,
springback
,
annealing
LI Wei-gang
,
GUO Zhao-hui
,
YI Jian
,
LIU Xiang-hua
钢铁研究学报(英文版)
An optimization solution to roll shifting strategy for alternately rolling campaign is presented. All the strips in a rolling campaign are divided into narrow strips and wide ones, and shifting position of narrow strips is obtained by the recursive method, and then shifting position of wide strips is optimized by NSGA-II which is a multi-objective genetic algorithm. For wide strips, a multi-objective optimization model of roll shifting strategy is proposed, which takes 3 wear contour factors including edge smoothness, body smoothness and edge drop as optimization objectives. The Pareto optimal front of roll shifting strategy can be gained quickly by NSGA-II, which suggests a series of alternative solutions to roll shifting strategy. Analysis shows that the conflict exists among the 3 objectives. The final optimal solution is selected from the Pareto optimal solutions by the weighted-sum decision-making method. Industrial production proves the validity of the solution, and it can improve strip profile of alternately rolling, reduce strip edge wave, and extend the rolling miles of rolling campaigns.
关键词:
hot strip mill
,
alternately rolling
,
work roll shifting
,
NSGA-II
,
pareto optimal solution
DING Jing-guo
,
QU Li-li
,
HU Xian-lei
,
LIU Xiang-hua
钢铁研究学报(英文版)
There is a certain extent of measuring error for each pyrometer in plate production process, which has a great impact on process control system. A soft sensor technique is used to calculate the confidence interval of measuring temperature data from pyrometers and an inference estimator is designed by partial least square method, then the pyrometer with highest confidence is considered as the reference one, with which inference estimation for measured data on-line of other pyrometers is started and the measuring error is conformed. From actual application it can be found that this method can improve the measuring accuracy by 3%-5%, and has high field application value.
关键词:
plate mill
,
soft sensor
,
temperature inference
,
partial least square
ZHOU Min
,
DU Lin-xiu
,
LIU Xiang-hua
钢铁研究学报(英文版)
The variation of heat treatments including directed quenching and tempering off-line after controlled rolling (DQT) and quenching off-line and tempering off-line after controlled rolling (RQT) with microstructure and mechanical properties of a low-carbon microalloyed steel was compared and analyzed. For DQT, the quenched steel was obviously banded microstructure, with increasing tempering temperature, lath martensite coarsened, the cusp carbide precipitated at grain boundaries, the yield strength fluctuated slightly, and the fracture-separation was obvious. The impact toughness was better in the steel tempered at 500 ℃ for 1 h. In RQT, with increasing tempering temperature, lath martensite degenerated, intragranular and intergranular finer precipitations with smaller than 30 nm precipitated and grew up and were distributed dispersedly, the stripe-like carbides were distributed at grain boundaries, and the yield strength and tensile strengthen decreased obviously. The impact toughness of RQT process was much better than that of DQT process, and the comprehensive mechanical properties were better for the steel tempered at 500 ℃ for 1 h of RQT process.
关键词:
X120 pipeline steel
,
heat treatment
,
microstructure
,
mechanical property
,
fracture-separation
