780mpa grade hot-rolled steel plate for hydraulic bulging and its preparation method

A technology of hydraulic bulging and hot-rolled steel plates, which is applied in metal rolling, heat treatment equipment, manufacturing tools, etc., can solve the problems of poor formability of high-strength steel, achieve high fatigue performance, suppress dislocation disappearance, and increase bit density Effect

Active Publication Date: 2022-03-22
PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The technical problem to be solved by the present invention is the poor formability of the existing 780MPa high-strength steel

Method used

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  • 780mpa grade hot-rolled steel plate for hydraulic bulging and its preparation method
  • 780mpa grade hot-rolled steel plate for hydraulic bulging and its preparation method
  • 780mpa grade hot-rolled steel plate for hydraulic bulging and its preparation method

Examples

Experimental program
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Effect test

preparation example Construction

[0030] The preparation method of the above-mentioned 780MPa level hydraulic bulging hot-rolled steel plate comprises the following steps:

[0031] a. Prepare billets according to the chemical composition of hot-rolled steel plates for 780MPa grade hydraulic bulging;

[0032] b. Rough rolling: rough rolling the heated billet for 5-7 passes to obtain an intermediate billet, controlling the deformation of each pass in the first 2 passes to be ≥18%, and the deformation of each pass in the remaining passes to be ≥20%;

[0033] c. Finish rolling: the start rolling temperature is 1020-1080°C, the finish rolling temperature is 850-900°C, and the thickness of the steel plate after finish rolling is 2-8mm;

[0034]d. Laminar cooling: the steel plate obtained in step c is ultrafast cooled to 580-640° C. at a cooling rate of >60° C. / s.

[0035] In the above step a, the conventional converter smelting process is adopted, the molten iron desulfurization→converter smelting combined blowing→...

Embodiment

[0045] This embodiment provides 5 groups of 780MPa grade hot-rolled steel sheets for hydraulic bulging prepared by the preparation method of the present invention, such as examples 1, 2, 3, 4 and 5, and 780MPa grades in examples 1, 2, 3, 4 and 5 The components of the hot-rolled steel sheets for hydraulic bulging are designed to be the same, as shown in the examples in Table 1. The present invention provides two groups of comparative examples, such as comparative examples 1 and 2, the chemical components of comparative examples 1 and 2 are the same, as shown in the comparative examples in Table 1.

[0046] The chemical composition of table 1 embodiment and comparative example

[0047]

[0048] The preparation of the 780MPa level hydraulic bulging hot-rolled steel plate of example 1, 2, 3, 4 and 5 comprises the steps:

[0049] a. Using conventional converter smelting process, molten iron desulfurization→converter smelting combined blowing→deoxidation, alloying→replenishing A...

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Abstract

The invention discloses a 780MPa grade hot-rolled steel plate for hydraulic bulging and a preparation method thereof, belonging to the technical field of iron and steel material engineering. The hot-rolled steel sheet for 780MPa grade hydraulic bulging of the present invention has a chemical composition of C0.02-0.04%, Si 0.05-0.10%, Mn 1.7-2.00%, Nb 0.040-0.050%, and Ti 0.070-0.080%. , V 0.030‑0.060%, Mo 0.20‑0.30%, P≤0.02%, S≤0.003%, N≤0.0040%, Als 0.010‑0.050%, Ca 0.0020‑0.0050%, and the rest are Fe and unavoidable impurities. The invention adopts micro / low C-Nb-Ti-Mo micro-alloyed composition system, and obtains the microstructure of ultra-fine crystal acicular ferrite and nano-precipitated phase through controlled rolling and controlled cooling technology. The mechanical properties of the steel plate of the present invention meet: its yield strength ≥ 650MPa, tensile strength ≥ 780MPa, elongation ≥ 21%, n value ≥ 0.10, 180 ° cold bending test d = 1.5a qualified, grain size ≥ 12 grades, can be Effectively solve the problem of poor formability of the existing 780MPa high-strength steel.

Description

technical field [0001] The invention belongs to the technical field of iron and steel material engineering, and in particular relates to a hot-rolled steel plate for 780MPa grade hydraulic bulging and a preparation method thereof. Background technique [0002] With the rapid development of the automobile industry, while automobiles bring convenience to people's lives, they also bring many problems, among which safety and environmental protection have become the most core topics. In order to solve these problems, lightweight vehicle body came into being. In addition to the optimized design of the car body structure and the use of high-strength materials, the optimization of the part structure, such as "replacing solid with space" and variable cross-section design, can not only reduce the mass, but also make full use of the strength and stiffness of the material. Hydraulic bulging technology is an advanced manufacturing technology developed to meet this requirement. The hydr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14C21D6/00C21D8/02C21D9/00B21B1/26
CPCC22C38/02C22C38/04C22C38/12C22C38/14C22C38/06C22C38/002C21D8/0226C21D9/0081C21D6/005C21D6/008B21B1/26C21D2211/005C21D2211/009
Inventor 汪创伟李正荣崔凯禹曾瀚
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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