Production of Ultrafine Grained API X70 Steel with Controlled Rolling

2013 ◽  
Vol 829 ◽  
pp. 884-888
Author(s):  
Reza Abdideh ◽  
Mohammad Hizombor ◽  
Reza Mohammadian Rad ◽  
Iman Mohammad Zadeh
Keyword(s):  
Thermomechanical Treatment ◽  
High Strength ◽  
Cost Effective ◽  
Mechanical Tests ◽  
Controlled Rolling ◽  
Rolling Temperature ◽  
Microalloyed Steels ◽  
Finish Rolling Temperature ◽  
Finish Rolling ◽  
Ultrafine Grained

Development of industries in recent years reveals the essential need to the microalloyed steels with high strength and good ductility. Refinement of Ferrite grains by thermomechanical Treatment is the only lower cost effective method to improve strength and toughness spontaneously in this type of steels. API X70 steel belongs to high strength microalloyed steel group. The manufacturing process of this steel is controlled rolling which is a kind of thermomechanical treatment and it is considered as a grain refining method. In this research, three specimens of API X70 steel were experimentally rolled in order to achieve ultrafine grained microstructure. Rolling operations are designed in such a way that the rolling of these specimens finished at 846, 823 and 800°C. Results of the experiments were analyzed by mechanical tests and microstructures observations. The microstructure observations show that decreasing of finish rolling temperature causes decrease in Ferrite grain size. Results also show that rolling of API X70 steel in the vicinity of Ar3temperature and high strain rates lead to ultrafine Ferrite grains in microstructure. This is due to the transformation of work hardened austenite to Ferrite. On the other side, Tensile and impact tests show that decreasing of finish rolling temperature causes increasing in yield and tensile strength and also improves the toughness.

Microstructure Influenced by Controlled Rolling, Cooling and Thermal Processing of Seamless Tubes Made of Steel 25CrMo4

2020 ◽  
Vol 405 ◽  
pp. 121-126
Author(s):  
Petr Kawulok ◽  
Ivo Schindler ◽  
Stanislav Rusz ◽  
Rostislav Kawulok ◽  
Petr Opěla ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Controlled Rolling ◽  
Rolling Temperature ◽  
Compression Tests ◽  
Structural Variations ◽  
Finish Rolling Temperature ◽  
Finish Rolling ◽  
Physical Simulations ◽  
Plain Strain ◽  
Quenching And Tempering

By use of physical simulations, it was studied the influence of finish rolling temperature (from 820 °C to 970 °C) on the microstructural and mechanical properties of seamless tubes with a different wall thickness (from 6.3 to 40 mm) – in the state after rolling as well as after quenching and tempering. In laboratory conditions, by use of the Simulator HDS-20, the bloom piercing and rolling of the seamless tubes from 25CrMo4 low-alloy steel in a pilger mill were in a simplified way simulated. The wall thickness of the tube influenced the total deformation of specimens at anisothermal multi-pass plain-strain compression tests as well as the final cooling rate. The quenching and tempering of the deformed specimens was subsequently performed with use of the electric resistance furnaces. The finish rolling temperature had only insignificant effect on the resulting properties. Markedly lower hardness was obtained only after the simulation of tube production with the wall thickness of 40 mm contrary to the wall thickness of 6.3 and 20 mm. Structural variations of the specimens after rolling simulations were more or less overlapped by the subsequent quenching from the temperature of 850 °C and tempering at the temperature of 680 °C.

Laboratory Controlled Rolling of Microalloyed Steel for Production of Seamless Tubes

2016 ◽  
Vol 258 ◽  
pp. 611-614 ◽  
Author(s):  
Petr Kawulok ◽  
Radek Jurča ◽  
Ivo Schindler ◽  
Stanislav Rusz ◽  
Rostislav Turoň ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Hsla Steel ◽  
Tensile Tests ◽  
Strength Properties ◽  
Controlled Rolling ◽  
Rolling Temperature ◽  
Plastic Properties ◽  
Finish Rolling Temperature ◽  
Finish Rolling ◽  
Rolling Temperatures

Using the laboratory rolling mill with smooth rolls, piercing, as well as rolling in a pilger mill of the seamless tubes with diameter 273 mm from the HSLA steel microalloyed with vanadium steel was simulated. Influence of the wall thickness (6.3 – 40 mm) and finish rolling temperature on the final structural and mechanical properties was investigated. Necessary temperatures of the phase transformations in the course of cooling were determined by dilatometric tests. Based on the dilatometry results, finish rolling temperatures were reduced. Lower rolling temperatures yielded in a relative grain refinement. Effect of the finish rolling temperature did not have any marked impact on the tensile tests results. Strength properties decreased only slightly with the increasing wall thickness and the plastic properties were not influenced significantly by this parameter. The positive effect of the reduced finishing temperature appeared markedly in the results of impact tests performed at room temperature only. Notch toughness was increased by approx. 25 % in the case of the wall thickness of not less than 20 mm.

Thermal-Mechanical Simulation of the Controlled Rolling and Cooling Process by Orthogonal Design for Pipeline Steel

2012 ◽  
Vol 557-559 ◽  
pp. 2355-2360 ◽  
Author(s):  
Min Jiang ◽  
Li Na Chen ◽  
Wei Pang ◽  
Chong He Li ◽  
Xiong Gang Lu
Keyword(s):  
Cooling Rate ◽  
Heating Temperature ◽  
Pipeline Steel ◽  
Great Influence ◽  
Control Process ◽  
Controlled Rolling ◽  
Rolling Temperature ◽  
Cooling Temperature ◽  
Finish Rolling Temperature ◽  
Finish Rolling

A novel pipeline steel was prepared by the vacuum inducting technology, using Gleeble-3500 hot simulator, its parameters of thermo-mechanical control process (TMCP), such as heating temperature, finish rolling temperature, finish cooling temperature and cooling rate, have been studied by the orthogonal experiment with four factors and three levels. Through the orthogonal theoretical analysis, it is found that the sequence of the effect of parameters on the mechanical property is: Cooling rate > Heating temperature > Finish cooling temperature > Finish rolling temperature, the cooling rate is the most important factor affecting the inspection target and possesses a great influence on the hardness of the pipeline steel.

scholarly journals The Effects of Finish Rolling Temperature and Niobium Microalloying on the Microstructure and Properties of a Direct Quenched High-Strength Steel

2017 ◽  
Vol 62 (2) ◽  
pp. 619-626 ◽  
Author(s):  
A. Kaijalainen ◽  
N. Vähäkuopus ◽  
M. Somani ◽  
S. Mehtonen ◽  
D. Porter ◽  
...  
Keyword(s):  
High Strength ◽  
Rolling Temperature ◽  
Rolled Strip ◽  
Low Carbon ◽  
Finish Rolling Temperature ◽  
Niobium Microalloying ◽  
Finish Rolling ◽  
Nb Microalloying ◽  
Hot Rolled ◽  
Cct Diagrams

AbstractThis paper comprehends the effects of finish rolling temperature (FRT) and Nb-microalloying on the microstructural evolution and resultant properties of a low carbon direct quenched steel in the yield strength category of ≥900 MPa. Results indicate that a decrease in FRT close to Ar3temperature significantly influenced the microstructure following phase transformation, especially at the subsurface (~50-400 μm) of the rolled strip. On decreasing the FRT, the subsurface microstructure revealed a fine mixture of ferrite and bainite obviously as a result of strain-induced transformation, whereas the structure at the centreline remained essentially martensitic. Further, Nb-microalloying promoted the formation of ferrite and bainite even at higher FRTs, thus influencing the mechanical properties. The microstructures of the hot-rolled strips were further corroborated with the aid of CCT diagrams.

Improvement of Mechanical Properties and Corrosion Resistance by Deformation Induced Precipitation in Al-Zn-Mg-Cu Alloy

2017 ◽  
Vol 898 ◽  
pp. 179-190 ◽  
Author(s):  
Jin Rong Zuo ◽  
Long Gang Hou ◽  
Jin Tao Shi ◽  
Hua Cui ◽  
Lin Zhong Zhuang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Thermomechanical Treatment ◽  
High Strength ◽  
Alloy Sheet ◽  
Rolling Temperature ◽  
Al Alloy ◽  
Deformation Degree ◽  
Dynamic Aging ◽  
Final Rolling Temperature ◽  
Final Rolling

A final thermomechanical treatment (FTMT) including peak aging and subsequent dynamic aging was proposed to prepare 7055 Al alloy sheets. The optimization was based on nine well-planned orthogonal experiments. Three main processing conditions in the thermomechanical treatment for obtaining the optimum synthetic properties of 7055 (i.e. preheating temperature, final rolling temperature and deformation degree) were investigated. It was shown that the final rolling temperature is the most important factor among the three parameters, and the optimum properties (yield strength: 651 MPa, ultimate tensile strength: 660 MPa) of 7055 Al alloy sheet can be gained with preheating at 140oC and 40% deformation at 170oC. With dynamic aging, grain boundary precipitates became discontinuous without much coarsening of matrix precipitates, while they were continuously distributed after T6 aging. The present optimal FTMT process can improve the intergranular / exfoliation corrosion resistance without sacrificing the strength compared to T6 tempering. The present FTMT process as a good alternative can produce high-strength Al alloy sheets with high strength and good corrosion resistance efficiently and economically.

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