JP3721517B2 - Method for evaluating the effect of degree of work and annealing on mechanical properties in bending of steel sheets - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for evaluating the influence of workability and annealing treatment on mechanical properties in bending of steel plates such as press-bend steel pipes and hunched beams.
[0002]
[Prior art]
Opportunities for using press-bend steel pipes as building steel columns and truss materials are increasing. A press-bend steel pipe is manufactured by forming a raw steel plate into a round shape in the order of a U shape and an O shape at room temperature using a horizontally long press, and then welding and joining the end portions of the raw steel plate. For this reason, the mechanical properties (0.2% proof stress Yp, tensile strength Ts, yield ratio YR = Yp / Ts) of the raw steel plate change due to work hardening in the steel pipe immediately after pipe forming. These materials change greatly as the strength of the steel plate is high and the degree of processing (t / D = plate thickness / diameter) is large, and those whose mechanical properties change excessively may exceed the standard value. In this case, the annealing process (SR process) is performed so as to satisfy the standard value.
[0003]
[Problems to be solved by the invention]
However, these series of process managements have been left up to the steel plate manufacturers and steel plate processors so far as black boxes. Therefore, there is a problem that it is difficult to sufficiently secure the quality of the steel structure that is shifting to the performance design method that determines the design required performance value according to the importance of the building.
In addition, SR processing is costly and requires a strength test after SR processing. Conventionally, all of the components exceeding the standard value are SR processed, which increases the cost accordingly. are doing.
The above-mentioned problem is a common problem in bending of not only press bend steel pipes but also steel plates such as hunched beams.
The present invention solves the above-mentioned conventional problems, and by clarifying the material characteristics of the bent steel sheet, the quality, safety and reliability of the steel structure are further improved and the cost is reduced. It is an object to provide a method for evaluating the influence of the degree of work and the annealing treatment on the mechanical properties in bending of a steel sheet that can be deformed.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the degree of work and the effect of annealing treatment on the mechanical properties in bending of the steel sheet of the present invention are evaluated in the following order.
(1) Mechanical properties (0.2% proof stress Yp-p1, tensile strength Ts-p1, yield ratio YR-p1), carbon equivalent (Ceq), degree of work (t / D), SR treatment temperature (T C) is positioned as an influential factor on the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel sheet after bending and SR treatment of the steel sheet, and a multiple regression analysis is performed.
(2) From the results of multiple regression analysis,
An estimation formula for the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel sheet after SR treatment represented by the following formula is constructed.
Yp-sr = a · Yp-p1 + b · Ceq + c · (t / D) + d · T ° C + e
Ts-sr = a.Ts-p1 + b.Ceq + c. (T / D) + d.T.degree. C. + e
YR-sr = a ・ YR-p1 + b ・ Ceq + c ・ (t / D) + d ・ T ℃ ＋ e
(3) Taking into account the quality characteristic distribution of each steel manufacturer by each steel manufacturer, the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel sheet after bending and SR treatment using the above estimation formula ).
{Circle around (4)} Determine whether the trial calculation result satisfies the design required performance value of the building, and clearly indicate the necessity of SR processing and the SR processing temperature.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1-6 is a figure for demonstrating embodiment which applied this invention to the press bend steel pipe.
FIG. 1 shows a part of test data of a press bend steel pipe manufactured from various raw steel plates. The manufacturer's name, steel type, carbon equivalent (Ceq), and mechanical properties (0.2% proof stress Yp-sr, tensile strength Ts-sr, yield ratio YR-sr) of the steel plate are shown. The mechanical properties (0.2% proof stress Yp-sr, tensile strength Ts-sr, yield ratio) of steel pipes after press bend processing and SR treatment at each degree of work (t / D) and SR treatment temperature (T ° C) YR-sr) is shown.
[0006]
Based on the test data in Fig. 1, the mechanical properties (Yp-p1, Ts-p1, R-p1), carbon equivalent (Ceq), degree of processing (t / D), and SR treatment temperature (T ° C) Was positioned as an influencing factor on the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel pipe after press bend processing and SR treatment, and multiple regression analysis was performed.
[0007]
FIG. 2 is an estimation formula showing the result of multiple regression analysis. The mechanical properties (0.2% proof stress Yp-sr, tensile strength Ts-sr, yield ratio YR-sr) of the steel pipe after press bend processing and SR treatment are the mechanical properties of the steel plate (Yp-p1, Ts- p1, R-p1), carbon equivalent (Ceq), degree of processing (t / D), SR treatment temperature (T ° C), and the estimation accuracy of the estimation equation shown in FIG. 2 is as shown in FIG. is there.
Using the estimation formula shown in FIG. 2, the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel pipe after press bend processing and SR treatment can be estimated as shown in FIG. it can.
[0008]
From the calculation results in FIG. 4, the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel pipe after press bend processing and SR treatment, SR treatment temperature (T ° C), carbon equivalent (Ceq) and The relationship of the degree of processing (t / D) is represented by FIG. 5 (A) to FIG. 5 (C), respectively. In FIG. 5, Yp = 325 (N / mm ² ) or more, Ts = 490 (N / mm ² ) or more, and YR = 80 (%) or less are design required performance values.
[0009]
From the estimation results in Fig. 4, as shown in Fig. 6, depending on the mechanical properties (Yp-p1, Ts-p1, R-p1), carbon equivalent (Ceq), and workability (t / D) of the steel plate, Decide SR treatment policy for bend steel pipes that SR treatment is not necessary (○), what is necessary (550: treatment temperature) and unselectable (×: design performance value not satisfied even after SR treatment) Can be evaluated.
[0010]
For example, when a press bend steel pipe is manufactured from a raw steel plate indicated by X in FIG. 4 at a working degree of 5.1% and an SR treatment temperature of 20 ° C., the mechanical properties of the steel pipe after SR treatment are Yp = 444, Ts = 597 and YR = 74, which satisfy the above-mentioned required design performance value, and it is determined that the SR process is unnecessary. It should be noted that the mechanical property does not change unless the SR treatment temperature is actually about 550 ° C., and it is determined that the SR treatment is unnecessary at 20 ° C.
[0011]
Further, when a press bend steel pipe is manufactured from the raw steel plate indicated by Y in FIG. 4 at a working degree of 8.3% and an SR treatment temperature of 500 ° C., the mechanical properties of the steel pipe after SR treatment are Yp = 396, Ts = 499 and YR = 79, which satisfy the above-mentioned required design performance value, and it is determined that SR processing is necessary.
Further, when a press-bend steel pipe is manufactured from the raw steel sheet indicated by Z in FIG. 4 at a workability of 9% and an SR treatment temperature of 20 ° C., the mechanical properties of the steel pipe after SR treatment are Yp = 481, Ts = 565, YR = 85. At this time, no matter how much the SR processing temperature is raised, YR = 80 (%) or less cannot be selected. Therefore, selection is not possible (×: design required performance value is not satisfied even after SR processing) Is determined.
[0012]
Based on the above determination results, the construction company can select and order a material steel plate that does not require SR processing and satisfies the design required performance value from the steel material manufacturer, thereby reducing the construction cost. be able to.
[0013]
FIG. 7 is a view for explaining an embodiment in which the present invention is applied to a haunch beam. In the haunch beam, the lower steel plate of the beam is bent at the point P. Therefore, mechanical properties (0.2% proof stress Yp-p1, tensile strength Ts-p1, yield ratio YR-p1), carbon equivalent (Ceq), workability (t / D), SR treatment temperature (T ℃) ) Is a factor affecting the mechanical properties (Yp-sr, Ts-sr, YR-sr) of steel plates after bending and SR treatment, and multiple regression analysis was conducted. Can be evaluated.
[0014]
【The invention's effect】
As is clear from the above description, according to the present invention, it is possible to reliably and quantitatively create a design required performance value for a bent steel sheet based on the performance design method. Moreover, by clarifying the material characteristics of the bent steel sheet, the quality, safety and reliability of the steel structure can be further improved, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 to FIG. 6 are diagrams for explaining an embodiment in which the present invention is applied to a press bend steel pipe, and FIG. FIG.
FIG. 2 is a diagram showing an estimation formula for mechanical properties of a steel pipe after press bend processing and after SR treatment.
FIG. 3 is a diagram showing the estimation accuracy of the estimation formula of FIG. 2;
FIG. 4 is a diagram showing a part of a trial calculation result of mechanical properties of a steel pipe after press bend processing and SR processing using the estimation formula of FIG. 2;
FIG. 5 is a diagram showing the relationship between the mechanical properties of a steel pipe after press bend processing and after SR treatment, the SR treatment temperature, the carbon equivalent, and the working degree.
6 is a diagram showing a part of the evaluation result of a press bend steel pipe based on the trial calculation result of FIG.
FIG. 7 is a diagram for explaining an embodiment in which the present invention is applied to a haunch beam.

Claims (1)

Mechanical properties (0.2% proof stress Yp-p1, tensile strength Ts-p1, yield ratio YR-p1) and carbon equivalent (Ceq), degree of work (t / D = plate thickness / bending diameter), SR treatment Positioning temperature (T ° C) as an influencing factor on the mechanical properties (Yp-sr, Ts-sr, YR-sr) of steel plates after bending and SR treatment, ,
From the result of the multiple regression analysis, a process of constructing an estimation formula for the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel sheet after SR treatment represented by the following formula;
Yp-sr = a · Yp-p1 + b · Ceq + c · (t / D) + d · T ° C + e
Ts-sr = a.Ts-p1 + b.Ceq + c. (T / D) + d.T.degree. C. + e
YR-sr = a ・ YR-p1 + b ・ Ceq + c ・ (t / D) + d ・ T ℃ ＋ e
Taking into account the quality characteristics distribution of each steel manufacturer, the mechanical properties (Yp-sr, Ts-sr, YR-sr) of the steel sheet after bending and SR treatment are estimated using the above estimation formula. With a process to
Determining whether the trial calculation result satisfies the design required performance value of the building, and clearly indicating the necessity of SR treatment and the SR treatment temperature; Method for evaluating the effect of annealing treatment.

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