Effect Of Hot Rolling Conditions Research Articles

Effect of hot rolling conditions on the nitride precipitation process in low carbon steel strips

The nitride precipitation process plays an important role in the final mechanical and aging behaviour of low carbon steels in hot rolled state as well as in cold rolled and annealed state. The nitride precipitation process is investigated in an indirect manner: instead of measuring the amount of nitrogen compounds, the free nitrogen content of the samples was measured using a special thermomechanical treatment and a thermoelectric power tester. It was found, that the free nitrogen content in a steel strip strongly depends on three main factors: on the position in strip transverse direction, on the coiling temperature and on the cooling method at the run-out table of the hot rolling mill.

Effect of Hot-rolling Conditions on Texture and R-value of 16%Cr Ferritic Stainless Steel

Effect of Hot-rolling Conditions on Texture and R-value of 16%Cr Ferritic Stainless Steel

The Effect of Recrystallization on Interphase Precipitation in Hot-Rolled Steel Sheet

Hot-rolled steel products with high strength and good formability are in demand for automobile body parts, particularly steels which can reduce weight without sacrificing vehicle safety. Recent studies have suggested that interphase precipitation (IP) hardening is a promising approach for obtaining excellent high strength and superior formability from low-alloy steels. However, the effects of hot rolling conditions and alloying elements on IP hardening have not been clearly determined. In this study, we sought to clarify the above effects by analyzing the recrystallization behavior during hot rolling. As a result of sample testing and analysis, it was determined that the recrystallization which occurs during hot rolling plays a critical role in enhancing the IP hardening of low-alloy steels.

クラッド鋼板の先後端部変形におよぼす圧延条件の影響

クラッド鋼板の先後端部変形におよぼす圧延条件の影響

Texture evolution and formability under different hot rolling conditions in ultra purified 17%Cr ferritic stainless steels

A very non-uniform γ-fiber recrystallization texture usually takes place in ferritic stainless steels, which can deteriorate the formability of final sheets. In order to work out the way of improving the uniformity of γ-fiber recrystallization texture, conventional rolling and warm rolling processes have been carried out with an ultra purified ferritic stainless steel. Texture evolution under different hot rolling conditions was investigated by using macro and micro-texture analyses. It was observed that a non-uniform γ-fiber recrystallization texture was obtained in the final sheet after conventional rolling process, while a nearly uniform γ-fiber recrystallization texture was formed in the final sheet after warm rolling process. Therefore, the formability of the final sheet was significantly improved after warm rolling process. It was indicated that the formation of non-uniform γ-fiber recrystallization texture was attributed to oriented nucleation, whereas the formation of uniform γ-fiber recrystallization texture was explained by a combination of oriented nucleation and preferred growth. ► Effect of hot rolling conditions on texture evolution was studied. ► Uniform γ-fiber recrystallization texture was formed after warm rolling process. ► Formability was improved by employing the warm rolling process. ► The development mechanism of recrystallization texture was explored.

Influence of Composition and Hot Rolling Conditions on Microstructure and Texture of Nb-Ti Stabilized FSS

In this paper, the influence of chemical compositon on the formability of γ-fibre texture, and the hot band microstrcture has been studied. Experiments have been conducted to investigate the effect of hot rolling conditions. Nb-Ti added and Nb-Ti free specimens hot rolled in differencd hot rolling conditions have been compared. The results show that, the change in band width is dependent on hot rolling tempreture. When the hot band are rolled at the temperature of 1150-950 °C, large sizes on ferrite grain are observed, and this character is presented more obviously in the specimen with no Nb-Ti. As the incresaing of the hot rolling temperature, the intensity of γ-fibre texture decreases. γ-fibre texture presented in Nb-Ti added specimen is stronger under three hot rolling conditions.

Ti 添加 Dual Phase 鋼の疲労限に及ぼす熱間圧延条件の影響

The effects of hot rolling conditions on the size of TiC precipitates in Ti-added ferrite-martensite hot-rolled steel sheets and precipitated TiC size on fatigue limit were investigated. Steel sheets were hot-rolled at 1153 K or 1073 K and rapidly cooled to 953 K after hot-rolling and air-cooled for several seconds in order to accelerate ferrite transformation and rapid cooled again to coiling temperature. It was found that TiC particles were coarsened with the decline of finish-rolling temperature (FRT) and the increase of air-cooling time after hot rolling. This is presumably because the decrease of FRT raises the ferrite transformation temperature and TiC precipitation temperature; and the increase of air-cooling time from 953 K results in the coarsening of TiC particles due to growth or Ostwald growth of TiC. As for the relationship between TiC particle size and fatigue limit, it was found that fatigue limit was maximized when the average size of TiC particle was about 7 nm. This indicates that the fatigue limit of Ti added ferrite-martensite hot-rolled steel sheets depends upon precipitation strengthening of precipitates which are not cut by dislocations.

Effects of Thermomechanical Processing on Microstructure and Mechanical Properties Multiphase Steels Exhibiting a TRIP Effect

Effects of hot-rolling conditions on these steels are much less studied than their importance for practice would suggest. It should be emphasized that bainite transformation is the key reaction to enrich non-transformed austenite with carbon. This study was carried out in order to gain understanding of the effect of thermomechanical hot rolling on final microstructure and mechanical properties of C-Mn-Si TRIP steel. Fundamental of the transformation induced plasticity effect – TRIP is the stabilization of substantial amount of retained austenite down to the ambient temperature by thermomechanical processing and its subsequent transformation into strain induced martensite as a consequence of applied plastic deformation. The special prepared stepped specimens were rolled on laboratory tandem mill. The effects of finish rolling temperature, strain and isothermal bainite transformation temperature on mechanical properties of mentioned TRIP steel were evaluated (mechanical properties were examined with tension test). Major deformation, higher finishing rolling temperature and higher temperature of bainite hold result in drop in strength. Proportionately to the drop in strength, the ductility grows in the TRIP steel. Microstructures were examined with X-ray diffraction (retained austenite). Image analysis software was used to process SEM micrographs of structure (ferrite, bainite assessment). Plastometric testing was conducted on GLEEBLE 3800 thermo-mechanical simulator. First stage of experiment yielded stress-strain curves for various temperatures and strain rates. Gleeble 1500 was used for the remaining plastometric simulation. Specimens were reheated to austenitization temperature of 1100°C and soaked. Then they were cooled to the temperature of deformation and subsequently cooled at higher rate down to the bainitic transformation temperature (400 – 550 °C). Specimens were held at the bainitic transformation temperature and then air-cooled. Final microstructures were evaluated with respect to transformation diagrams and optical microscopy findings. Higher bainite volume fraction was found in the specimens cooled at higher cooling rate as compared with more slowly cooled specimens.

Effect of hot-rolling and heat-treatment conditions on the structure and mechanical and technological properties of nitrogen-bearing austenitic steel 05Kh22AG15N8M2F-Sh

The effect of hot-rolling conditions on the structure, strength, ductility, fracture toughness, and technological properties of the nonmagnetic steel 05Kh22AG15N8M2F-Sh containing 0.55% N has been studied. A homogeneous and fine-grained austenitic structure forms in the steel upon rolling at 1000–1050°C and a reduction of more than 60–70%. This structure provides the following properties: σ0.2 = 1044 N/mm2, σu = 1172 N/mm2, δ = 32%, ψ = 64%, and KCV = 1.06 MJ/m2 at −70°C. The possibility of recrystallization of the hot-rolled steel (deformed at 10–90% reductions) is checked upon its subsequent heating to 850–1200°C followed by water quenching. The steel is shown to have high strength, ductility, and fracture toughness and to retain an austenitic structure without cracks or exfoliation upon hot plastic deformation by rolling up to a 90% reduction.

Effect of hot rolling conditions to produce deep drawing quality steels for continuous annealing process

Most of cold rolled deep drawability steel sheets finds application in areas where forming is critical. Deep drawing sheet steel requires good mechanical properties and microstructures, as well as sufficient anti-aging characteristics. Therefore, deep drawing steels are produced by controlling these metallurgical factors and optimizing steelmaking, hot rolling, cold rolling and annealing processes. This paper explains the effect the microstructure and mechanical properties of hot rolling conditions on continuously annealed sheet properties in certain chemical composition. Experiments have been conducted to investigate the effect of hot rolling conditions. Consequently, it became clear that hot rolling conditions play an important role in producing continuous annealed deep drawing quality steels.

Effect of Hot Rolling Conditions on Deformation Behavior of Oxide Scale at High Temperatures

Effect of Hot Rolling Conditions on Deformation Behavior of Oxide Scale at High Temperatures

Effect of Hot Rolling Conditions on the Microstructure and Mechanical Properties of Fe-C-Mn-Si Multiphase Steels

There is a growing need for the high strength steels with high formability for many applications. Using the concept of transformation induced plasticity (TRIP) observed in austenitic steels, one can obtain the combination of high strength and high formability. However, these austenitic steels require a fairly large amount of alloying elements which impose several practical problems for their widespread applications. On the other hand, it has been shown that the dual phase steels possess the relatively good combination of strength and formability due to their characteristic microstructure. The major microstructural constituents of dual phase steels are soft ferrite and hard martensite/bainite with small amount of retained austenite. In recent years, the beneficial effect of retained austenite on the mechanical properties of dual phase steels have been re-recognized and accordingly, there have been several investigations on developing the so-called TRIP-aided dual phase steels having increased amount of retained austenite in the microstructure. Most investigations on these TRIP-aided dual phase steels have been concentrated on the effects of heat treatment conditions and alloying elements such as Si, Mn, C and P on the microstructure and mechanical properties of cold rolled sheet steels. There have also been a few studies on developing suchmore » steels by hot rolling, and the emphases of these studies are placed mostly on increasing the amount of retained austenite. However, the microstructure of these hot rolled steels is far from optimum, consisting of large packets of hard second phase particles. The main objective of the present study is to modify the microstructure of this class of steels by varying the hot rolling conditions. The steel used in the present study is Fe-0.2C-2Si-1.5Mn.« less

Recrystallization and Related Phenomena. Effect of Hot Band Microstructural Factors on Recrystallization Texture in Ti-added Ultra-low Carbon Cold-rolled Sheet Steels.

An examination has been made of the effect of hot rolling conditions, considered as thermal history, on the deep drawability and recrystallization texture formation in Ti-added ultra-low carbon cold-rolled sheet steels. The findings show that the average r-value of IF steel is significantly improved by refining the hot band grains, by decreasing the finish-rolling temperature in large thermal drop, to temperature even below the Ar 3 transformation temperature, during hot rolling process. However, the average r-values of sheets hot-rolled almost isothermally at a finish-rolling temperature below the Ar 3 transformation temperature deviate detrimentally, when compared with hot band of the same grain size. In this study, an attention has paid to the formation of texture throughout the hot rolling, cold rolling and annealing processes, in relation to deep drawability.

17%Crフェライト系ステンレス鋼の熱間圧延板金属組織とリジング特性に及ぼす熱間圧延条件の影響

17%Crフェライト系ステンレス鋼の熱間圧延板金属組織とリジング特性に及ぼす熱間圧延条件の影響

The effect of thermomechanical history upon the microstructure and magnetic properties of nonoriented silicon steels

A study has been conducted to evaluate the effect of hot rolling conditions on precipitation behavior of MnS and AIN, microstructure, texture, and subsequent magnetic properties of nonoriented silicon steels. TEM work showed that MnS particles act as nucleating sites for dissolved A1N by providing an interface on which to precipitate. It was established that for the steels studied, a decrease in reheat temperature and a corresponding increase in coiling temperature resulted in an improved texture and, subsequently, better final magnetic properties. These results were explained based upon the effect of steel composition and hot rolling history on recrystallization behavior in the hot band and continuously annealed strip.

ラインパイプ用ベイナイト熱延高張力鋼板の強度と靱性におよぼす熱延条件の影響

ラインパイプ用ベイナイト熱延高張力鋼板の強度と靱性におよぼす熱延条件の影響

熱間圧延後のフェライト変態開始温度に及ぼす圧延条件と化学成分の影響

熱間圧延後のフェライト変態開始温度に及ぼす圧延条件と化学成分の影響

連鋳スラブ中のポロシティの消滅におよぼす圧延条件の影響

連鋳スラブ中のポロシティの消滅におよぼす圧延条件の影響

ラインパイプ用高張力熱延鋼板のオーステナイト粒度と材質におよぼすホットストリップミル圧延条件の影響

ラインパイプ用高張力熱延鋼板のオーステナイト粒度と材質におよぼすホットストリップミル圧延条件の影響

Effect of hot-rolling conditions on the physical properties of a carbon steel

Effect of hot-rolling conditions on the physical properties of a carbon steel