JPS589932A - Manufacture of steel sheet having texture with (110)(001) as principal orientation component - Google Patents

Abstract

PURPOSE:To manufacture the titled steel sheet by rolling a steel contg. a sufficient amount of soluble (C+N) to cause violent dynamic strain aging and carrying out recrystallization annealing. CONSTITUTION:A steel contg.>=10ppm soluble (C+N) is rolled at 200-500 deg.C and >=20% draft to cause violent dynamic strain aging by dislocation moved during working and the interaction between C and N in the steel. Recrystallization annealing is then carried out to manufacture a steel sheet having a texture with developed (110)(001) orientation component. When the steel sheet is press-formed, the resulting parts have remarkably enhanced tensile rigidity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rolling-sintering process (second step (I)
IOJ (001) This relates to a new method for manufacturing ## steel plates for improving the tensile rigidity of press-formed parts obtained using Oreko steel plates by fully developing C# steel plates.

Hinoki rolled steel sheets are mainly used for press-forming automobile body parts (-), so conventionally cold-annealing is one of the main uses.
Round milling knee C: Therefore, deep drawability C: Favorable (
IIIJ II [The development of the 10,000-ranked people has been criticized only for the development of the 10,000-ranked people. However, recently, attention has been focused on reducing the weight of automobiles from the viewpoint of improving fuel efficiency, and reducing the thickness of the steel plates that make up the automobile body is being considered.

In this case, the problem is that the steel plate becomes thinner (secondarily, the tensile rigidity of the molded part decreases.
．． When these impact forces are applied, local depressions are created in the molded part. This resistance to the occurrence of wrinkles is called tension stiffness.

This tensile stiffness is calculated by the following formula (υ
As is clear from the above, as the thickness of the steel plate decreases, it deteriorates rapidly.

13oe: tm Here, S is tensile rigidity, E is Young's modulus, t is refractory thickness, and m is a constant depending on the panel shape and has a value of 1 to 3.

One possible means to prevent this is to increase the yaw ratio between the steel plates.

#1-like Young's modulus changes depending on the crystal orientation (set a region), and has a maximum value in the (111) direction, but conventionally !v1! was applied to ?t# rolled sheet 4 sheets In the joint area, itabyoku (100
Since Man'i is the Lord Man'i, @ Niyama 1 is honest [111]
The Young's modulus is high only in the direction, and the direction in which the Young's modulus is maximum is not included. This (: against/, (110
)(001) steel plate has (11
1) Since the longitudinal direction is included, the Young's modulus is maximum in that direction, so the tensile rigidity of the pressed part with the longitudinal direction is significantly improved.

Fuwajima: A steel whose hardness (C!+lJ) is 10 PPm or more is rolled at a reduction rate of 20% or more in a temperature range of 200 to 500°C, and then recrystallized annealed? Development of (110)(0<)1) azimuth component of the set area'4
r: The main outline of the manufacturing process of the WM plate, which is characterized by the following.

The contents of the present invention will be explained in detail below.

The basic principle behind the invention is to produce intense dynamic strain aging in the rolling step 1' prior to annealing, and to create a resultant structure after annealing by using a specially processed weave that is controlled by this process.
(11O) [001) The aim is to increase the acid component at the Ti position. What is m-shear strain aging? Luck during processing! l! 71 dislocations and the same bath in steel 0. This is strain aging during processing caused by interaction with N.

According to the results of detailed research related to the present invention, when dynamic strain aging occurs during rolling, a clearing region (hereinafter referred to as deformation strain) with particularly large processing strain is formed within the crystal grains.
&! During blunting, (110)(001) recrystallization nuclei are preferentially formed in the deformation zone, contributing to an increase in the (IIO)(001) million-position component in the cross-section region after annealing.

In order to produce such dynamic strain aging, the steel must first contain a sufficient amount of the same bath (! It is necessary that the hardness (0+N) measured in the bath is 10 PP10 or more.If the same bath (0+N) is less than 10 PPm, the degree of dynamic strain aging is small and the effect of non-invention is a lock. Can not.

First, the rolling temperature is less than 200°C.
In this case, the diffusion of O and N atoms in steel is slow, and the 01N atoms diffuse into dislocations.It takes too long for the FFr transition period to occur, and dynamic strain aging does not occur sufficiently.Also, 50
In the temperature range above 0°C, C and N diffuse quickly enough to easily reach O and N atoms, but the interaction between dislocations and C and N atoms is weak and the dynamic strain effect disappears. Therefore, the rolling strength must be within the range of 200 to 200 mm.

Further, if the rolling ratio during rolling is less than 1, the number of dislocations multiplied during rolling is small, and therefore, wJ type strain aging does not occur easily and there is no load movement. For this reason, the rolling reduction ratio must be 2o or more.

Since the effects of the present invention are manifested by recrystallization after rolling, it is necessary to perform recrystallization annealing under conditions that cause recrystallization after rolling under the above conditions.

In carrying out the present invention, it is sufficient that the steel material has a symmetry (0+N) of IQPPm or more, and no other special wood is required. However, due to the need to improve strength, resistance, etc., it is common to add Mn%A71Si, etc. The effects of the invention will appear.

Kawagoe under the conditions stipulated for non-invention is published with other pressures,
In other words, hot rolling - Kawagoe, Yogoe - cold treatment, or hot rolling - Yogoe -
Although it is effective to perform the rolling in combination with cold rolling, in this case, it is desirable that the rolling reduction in cold rolling is equal to or lower than that in hot rolling.

Example 1 Different steels of different types (C%N O)
The plate was heated to a temperature of 950°C and rolled out to a thickness of 2.0°C, followed by cooling with nitrogen. Table 1 shows the chemical components of these samples and the m of self-solution (0+N) evaluated by the circle sM dominant method.

W! I 1 Table These samples were heated at room temperature to
After rolling at a temperature of 00°C and annealing at 700°C for 5 minutes, x#I pole figures were created for each test punch at 700°C, and The xH reflection intensity ratio was determined based on the case of six elm-quasi samples of Kago Asaori.

The relationship between this Cll0)(001) intensity ratio, components, and process conditions is shown in FIGS. 1 and 2.

In Fig. 1, when the rolling temperature is 370°C, the reduction is 70 inches;
A, 30% pressure reduction; B, 10% pressure reduction; C, respectively.

In addition, in the second factor, sample layer 6 with a reduction rate of 50%: a, sample /
I61;t) Y indicated.

As is clear from Figure 1, IN! When the iI bath (OWN) is 110-PP or higher and the sample is rolled at a rolling reduction of 20% or higher (rolled at 370°C), the (110,) after annealing is
(001) The intensity ratio becomes significantly higher. In addition, Fig. 2 shows that the elongation at 200 to 500°C is (110) (001).
This shows that it contributes to a significant increase in the intensity ratio.

Example 2 Using the natural pressure plate of sample layer 7 in Table 1, the temperature was measured separately at 450°C (B in the figure) and 350°C (A in the figure).
% rolling, the recrystallization was completely completed with a 700'CX 10 minute i-blunt, and two types of samples were prepared, and the Young's modulus in each direction within the plate surface of the steel plate was measured using the vibration damping method.

The result is 7fr: As shown in Figure 3, as is clear from the figure, the Young's modulus of the uninvented material is particularly high in the direction of 45 to 67.5° from the rolling direction, and the tensile rigidity is low due to the principle of plastic mechanics. It also shows a significant improvement.

Example 3 0; 0-080%s1; LOO4, Mh; 0*3
0, P; (LOII8; 0.019, at
; < 0.001, N ; 0.0030 each wt%
Q Chemical m Chemically grown capped steel is commonly understood as 1250℃
After heating, it was rolled to a thickness of 2.0 C:M at a finishing temperature of 950°C, and then rolled at 400°C during air cooling (A in the figure) and MW (
B in the figure) After rolling 60% of each separately,
Recrystallization was completed by annealing at 700° C. for 5 minutes, and two types of samples were prepared, and the Young's modulus in the plate was measured using the same method as in Example 2. However, the same bath immediately before the 0% pressure treatment, (0+N) was measured using the internal friction method (: □).
The light was 43 PPm just before rolling at 00℃, and 30 PPm just before rolling in Muroba.

Figure 4 (: As is clear from the measurement results of Young's modulus shown in
2. It can be seen that the IX Komei material has a special Young's modulus in the direction of 45 to 67.5 degrees from the rolling direction, so it is a board with tensile properties.

[Brief explanation of the drawing]

Figure 1 shows hot-rolled sheets placed in the same bath (OWN) and after annealing (1
10) The T diagram and m2 diagram showing the relationship between the random strength ratio of the (001) million-position component and the (IIOJ (0
01) Figures W&3 and Figure 4, which show the relationship between the azimuth component and the random intensity ratio, are T diagrams showing the Young's modulus in each direction within the plane of the annealed plate. Opening force % (c - tu) (Pμm) Fig. 2 Loaf spreading degree 1 ji C) Broom 3' [ Fig. 4 θ 45 9θ h Branch piece Ujt in the stretching direction)

Claims (1)

[Claims] Same bath (m, v, 2 where (3+N) is 10 PPm or more
A thin W4 sheet whose main components are (110) and (001) is characterized by being rolled at a reduction rate of 20% or more in the temperature range of 00 to 500°C, and then recrystallized by W1. Manufacturing method.