Analysis and prevention of vertical cracking phenomena during deep drawing of hot- rolled sg295 steel strips

The objective of this work was to carry out tensile tests to investigate the effect of finishing temperature on mechanical adhesion of thermal oxide scale on hot-rolled low carbon steel strips. Two hot-rolled low carbon steel strips were produced in an industrial hot rolling line by fixing a coiling temperature at 620 °C and varying finishing temperatures at 820 and 910 °C. Two testing methods were conducted. First, each of a number of samples was subjected to a given imposed strain with ex-situ imaging of scale surface after straining. Second, only one sample was strained in a test with ex-situ imaging of scale surface at every 2 mm elongation of the sample. A spallation ratio, an area where scale was spalled out and normalised by the total area observed by microscope, was plotted as a function of the imposed strain. These two methods gave the same tendency of results as follows. At a given strain, the spallation ratio of scale on steel produced using higher finishing temperature was larger. The gradient of spallation ratio with respect to the imposed strain of that scale was also steeper. This reflects the higher susceptibility of scale to spall out with increasing imposed strain. This behaviour might be related to the larger thickness of scale on steel produced using higher finishing temperature. For the second testing method, lowering the magnification of microscope to observe scale spallation from 50x to 20x increased R2 of the curve of spallation ratio versus the imposed strain, as well as improved the reproducibility of the test.

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Microstructure, Texture and Inhibitors of the As-Cast and Hot Rolled Grain-Oriented Silicon Steel by Strip Casting

Materials Science Forum ◽

10.4028/www.scientific.net/msf.852.101 ◽

2016 ◽

Vol 852 ◽

pp. 101-104 ◽

Cited By ~ 1

Author(s):

Wen Qiang Liu ◽

Cheng Shuai Lei ◽

Han Mei Tang ◽

Hong Yu Song ◽

Hai Tao Liu

Keyword(s):

Hot Rolling ◽

Texture Evolution ◽

Fiber Texture ◽

Silicon Steel ◽

Rolling Reduction ◽

Recrystallization Annealing ◽

Goss Texture ◽

Steel Strips ◽

Columnar Grains ◽

Hot Rolled

The microstructure and texture evolution of the as-cast and hot rolled grain-oriented silicon steel strips was investigated, and the precipitation of the inhibitors of the hot rolled strips was clarified. The results showed that the microstructure of the as-cast strip was characterized by coarse columnar grains with strong {001}<0vw> fiber texture. The microstructure of hot rolled strips was composed of ferrite and pearlite and the microstructure was gradually refined with increasing hot rolling reduction. In the hot rolled strips, α and γ fiber textures were enhanced at the expense of initial {001}<0vw> fiber texture and Goss texture was generated in the surface and sub-surface layer with increasing hot rolling reduction. Besides, a great number of dispersed MnS particles with the size of 20-30nm were observed in the hot rolled strips. These MnS particles could act as the effective inhibitors during the second recrystallization annealing of the grain-oriented silicon steel.

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Comparison of formability of steel strips, which are used for deep drawing of stampings

Journal of Materials Processing Technology ◽

10.1016/0924-0136(96)02343-6 ◽

1996 ◽

Vol 60 (1-4) ◽

pp. 283-290 ◽

Cited By ~ 9

Author(s):

R. Cada

Keyword(s):

Deep Drawing ◽

Steel Strips

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Application of Recrystallization Texture Evolution Model to Predict Plastic Formability in Steel Strips

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.1954 ◽

2014 ◽

Vol 783-786 ◽

pp. 1954-1960

Author(s):

Toshiharu Morimoto ◽

Y. Fuyuki ◽

A. Yanagida ◽

Jun Yanagimoto

Keyword(s):

Recrystallization Texture ◽

Texture Evolution ◽

Steel Strip ◽

Rolling Texture ◽

Interstitial Free ◽

If Steel ◽

Taylor Model ◽

Steel Strips ◽

Cold Rolled ◽

Hot Rolled

T.M.C.P.(Thermo Mechanical Control Processing) has been widely used to improveplastic formability in steel strips. We have produced interstitial free steel(IF steel) strips and ferriticstainless-steel strips through T.M.C.P. rolling method. Optimizing conditions of hot rolling, hotrolled annealing, cold rolling and cold rolled annealing, we developed texture prediction model. Wecan predict rolling texture accurately using the conventional Taylor model. Moreover, we preciselypredict recrystallization texture classifying the total number of microscopic􀀁 slips which arecalculated using the Taylor model. We consider that these calculated results provednucleation-oriented model and two types of recrystallization and grain growth mechanisms exit inour studies. One mechanism is that grains which had the small total number of microscopic slips arepreferred orientation for the hot rolled and annealed ferritic stainless-steel strip. The othermechanism is that grains which had the high total number of microscopic slips are preferredorientation for the cold rolled and annealed IF steel strip.

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Strain Hardening and Stretch Formability Behavior of Triple Phase (TP) Steel Strips

Acta Metallurgica Slovaca ◽

10.36547/ams.27.3.1048 ◽

2021 ◽

Vol 27 (3) ◽

pp. 152-156

Author(s):

Maha ElMeligy ◽

Taher El-Bitar

Keyword(s):

Strain Hardening ◽

Volume Fraction ◽

Salt Bath ◽

Holding Time ◽

Forming Limit ◽

Stretch Forming ◽

Steel Strips ◽

Stretch Formability ◽

Rolled Condition ◽

Hot Rolled

The current work explores the strain hardening and stretches formability behaviour of the developed Triple Phase (TP) steel. Double quenched TP steel strips posse three distinguished stages of strain hardening on tensile forming. 1st stage represents the highest n-value reflecting resistance to homogeneous deformation, where steel can be safely stretched. 2nd and 3rd stage reveals lower n-values, where localized thinning exist. On Erichsen testing, the relationship between punch forming force and punch stroke exhibits two forming regions. The 1st region is delineated by a straight line showing an ultra-high strain-hardening rate, which represents a reversible elastic stretch forming. The 2nd forming region continues to a higher Erichsen punch stroke than that of the 1st region and presents the permanent plastic stretch forming behaviour. It is found that bainite and martensite clusters created, by double quenching, in TP-steel exaggerated the elastic stretch forming limit 10 times higher than the as-hot rolled condition. 7 min. holding time of strips in the salt bath is considered the most effective for the creation of a useful volume fraction of the bainite phase. However, 21 min. holding time in salt bath grows martensite laths through the bainite aggregates, affecting negatively on stretch formability.

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