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Manufacturing method for high strength sheet steel used for door reinforced pipes

A manufacturing method and a door reinforcing tube technology are applied in the manufacturing field of high-strength thin steel plates, which can solve the problems of unclearness, unclear influence, difficulty in obtaining hardness distribution, etc., and achieve the effect of high energy absorption

Active Publication Date: 2014-02-12
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the above scheme, the steel plate of 590 MPa grade with low C content is used as the target, and the welding speed and cooling speed of flash butt welding and resistance seam welding are also different, so it is necessary to use a large amount of C containing high-strength pipes such as 980 MPa or more. It is difficult to obtain the same hardness distribution in tubes with high quenching strengthening elements such as Mn and Mn.
In addition, in the welding heat-affected zone of the composite structure steel plate of the comparison material in the above-mentioned proposal, a softened zone can be seen, but similarly to the above, for a pipe of 980 MPa or more containing a large amount of elements with high quenching strengthening ability and a high welding speed, the resistance It is not clear whether the same hardness distribution can be obtained for seam welding, and its effect on the collapse of the pipe is also unclear

Method used

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  • Manufacturing method for high strength sheet steel used for door reinforced pipes
  • Manufacturing method for high strength sheet steel used for door reinforced pipes
  • Manufacturing method for high strength sheet steel used for door reinforced pipes

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0075] The steel having the chemical composition shown in Table 1 was smelted, hot rolled by a usual method, pickled, cold rolled, and then continuously annealed to obtain a thin steel sheet with a thickness of 2.0 mm.

[0076] This thin steel sheet was divided and subjected to resistance seam welding by high-frequency induction heating, thereby manufacturing a tube with a diameter of 31.8 mm.

[0077] While testing the mechanical properties of the thin steel plate, a crush test was performed on the obtained tube, and the hardness and the like were tested. It should be noted that the crush test is image 3 Under the main points shown (950mm span), such as Figure 4 As shown, the absorbed energy at 150mm indentation is obtained from the load-displacement curve.

[0078] These results are listed in Table 2 together.

[0079] According to Table 2 and figure 2 and Figure 4 The investigation is as follows.

[0080] In Comparative Example No. 1, the amount of C was small, so the tensile ...

Embodiment 2

[0095] The steel with the chemical composition shown in Table 3 is smelted, hot rolled by the usual method, pickled, cold rolled, and then continuously annealed under the conditions shown in Table 4 to obtain a thin steel sheet with a thickness of 2.0 mm .

[0096] This thin steel sheet was divided and subjected to resistance seam welding by high-frequency induction heating, thereby manufacturing a tube with a diameter of 31.8 mm.

[0097] While testing the mechanical properties of the thin steel plate, a crush test was performed on the obtained tube, and the hardness and the like were tested. It should be noted that the crush test is image 3 Under the main points shown (950mm span), such as Figure 4 As shown, the absorbed energy at 150mm indentation is obtained from the load-displacement curve.

[0098] These results are shown in Table 4 together.

[0099] In Comparative Example No. 15, the rapid cooling start temperature was low, so there were few low-temperature transformation ...

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Abstract

The invention provides a manufacturing method for high strength sheet steel used for door reinforced pipes. The pipes manufactured by resistance seam welding cannot fracture at welded parts during crushing and have high absorbed energy. The method employs steel composed of: 0.10-0.30% of C, 1.5-3.0% of Mn, less than or equal to 0.03% of P, less than or equal to 0.01% of S, less than or equal to 0.10% of Al, less than or equal to 0.0100% of N, C is smaller than or equal to 0.367-3.0*10<-3>(sigma B / 9.8)+1.5*10<-5>(sigma B / 9.8)<2> and is greater than or equal to 0.248-3.0*10<-3>(sigma B / 9.8)+1.5*10<-5>(sigma B / 9.8)<2>, and the steel also includes the balance Fe and inevitable impurities. The steel undergoes hot rolling and cold rolling by common methods, and is then subjected to continuous annealing, thus obtaining the pipe sheet steel with a low temperature phase change product content of more than 70% and a yield ratio of over 0.7.

Description

Technical field [0001] The invention relates to the manufacture of steel plates for motor vehicles, in particular to a method for manufacturing high-strength thin steel plates for door reinforcement pipes. Background technique [0002] In order to improve the fuel efficiency of the vehicle body and the safety in collision, the strengthening and weight reduction of vehicle reinforcement members are promoted. In particular, in door reinforcement members, currently 100MPa grade stamped products are mainly used. However, recently, as described in CAMP-ISIJ Vol. 2(1989)-2023, due to the higher strength of the pipe material in terms of weight reduction Favorable, so it has begun to be used. In order to obtain the same absorbed energy as the stamped product in such a pipe product, a high tensile strength of about 1470 MPa is required. [0003] In the prior art, in order to obtain such a high-strength pipe, the pipe is made by resistance seam welding of a thin steel plate of about 590MPa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/04C21D8/02
Inventor 内海幸博村上俊夫田中福辉鹿岛高弘前田广幸白泽秀则
Owner KOBE STEEL LTD