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High tensile strength hot rolled ferrite bainite dual phase steel and preparation method thereof

A technology with high tensile strength and tensile strength, applied in temperature control and other directions, can solve the problems of adverse effects of steel hole expansion performance, difficult steelmaking process, and high process requirements, and achieve excellent hole expansion performance and formability, and material cost. The effect of low cost and simple preparation process

Active Publication Date: 2010-02-10
INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Patent No. Publication No. CN101033522A discloses a fine-grained ferritic bainite dual-phase steel based on supercooled austenite deformation, which has good mechanical properties and low yield strength ratio, but silicon and The aluminum content is high, which increases the difficulty of the steelmaking process, and the process requirements are also high, especially the cooling rate after rolling is required to be controlled within a certain range. At the same time, a certain amount of Martensite, which adversely affects the hole expansion properties of the steel
The invention patent with the patent publication number CN1190997A discloses a dual-phase steel with a second phase of mainly polygonal ferrite and carbon-rich pearlite, which achieves high strength, good surface quality and matching of cold deformation properties of steel , but a certain amount of microalloying elements need to be added to the steel, which increases the production cost, and the high content of aluminum elements also brings certain difficulties to the steelmaking process
In addition, the invention patents with patent publication numbers US20050133124A1 and US20080202645A1 also proposed multi-phase steels with good strength, elongation and hole expandability. The microstructure of these steels contains 3-30% martensite and / or residual Austenite, others are one of ferrite and bainite or a combination of both, due to the existence of martensite, the hole expansion performance of steel is adversely affected to a certain extent
Also, the invention patent with the patent publication number CN101353757A discloses a hot-rolled high hole expansion rate steel plate with a tensile strength of 440 MPa. The hole expansion rate is very high, but its steel structure is a full bainite structure, and wherein More niobium, so the yield ratio is high and the stamping performance is poor

Method used

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  • High tensile strength hot rolled ferrite bainite dual phase steel and preparation method thereof
  • High tensile strength hot rolled ferrite bainite dual phase steel and preparation method thereof
  • High tensile strength hot rolled ferrite bainite dual phase steel and preparation method thereof

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Embodiment 1

[0034] Example 1: The steel ingot was smelted in a vacuum induction furnace, and its chemical composition is shown in Table 1. Rolling was performed on a laboratory 550mm reversing mill. The rolling process is as follows: heating the steel ingot to about 1200°C, keeping it warm for 1 hour, the rough rolling start temperature is about 1150°C, the finish rolling start temperature is 954°C, and the finish rolling finish temperature is 847°C. After 2 passes of rough rolling and 5 passes of finishing rolling, the thickness of the material is rolled from 90mm to 10mm, and the reduction ratio is distributed at 30%-30%-30%-25%-25%-25%-20%. Such as Figure 1 It shows that the cooling process is C1: about 30°C / s; air cooling start temperature T1: 718°C; air cooling time t1: 5s, C2: 20°C / s; coiling temperature T2: 487°C (simulated coiling with heat treatment furnace) , the mechanical properties of the obtained steel are shown in Table 2, and its structure is as follows figure 2 shown...

Embodiment 2

[0035]Example 2: Steel ingots were smelted in a vacuum induction furnace, and the chemical composition is shown in Table 1. Rolling was performed on a laboratory 550mm reversing mill. The rolling process is as follows: heating the steel ingot to about 1220°C, holding it for 1 hour, the start temperature of rough rolling is about 1136°C, the start temperature of finish rolling is 981°C, and the finishing temperature is controlled at 859°C. After 2 passes of rough rolling and 5 passes of finishing rolling, the thickness of the material is rolled from 90mm to 10mm, and the reduction ratio is distributed at 30%-30%-30%-25%-25%-25%-20%. The cooling process is C1: about 30°C / s, air cooling start temperature T1: 693°C, air cooling time t1: 3s, C2: 33°C / s; coiling temperature T2: 457°C (simulated coiling with heat treatment furnace), the obtained steel The mechanical properties are shown in Table 2, and the structure is similar to Example 1.

Embodiment 3

[0036] Example 3: Steel ingots were smelted in a vacuum induction furnace, and the chemical composition is shown in Table 1. Rolling was performed on a laboratory 550mm reversing mill. The rolling process is as follows: heating the steel ingot to about 1230°C, holding it for 1 hour, the rough rolling start temperature is about 1143°C, the finish rolling start temperature is 961°C, and the finish rolling finish temperature is controlled at 835°C. After 2 passes of rough rolling and 5 passes of finishing rolling, the thickness of the material is rolled from 90mm to 10mm, and the reduction ratio is distributed at 30%-30%-30%-25%-25%-25%-20%. Such as Figure 1 It shows that the cooling process is C1: about 30°C / s, air cooling start temperature T1: 706°C, air cooling time t1: 5s, C2: 40°C / s; coiling temperature T2: 451°C (simulated coiling with heat treatment furnace) , the mechanical properties of the steel obtained are shown in Table 2, and the structure is similar to that of E...

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Abstract

The invention relates to a hot rolled ferrite bainite dual phase steel of which tensile strength is not less than 490MPa and a preparation method thereof. The dual phase steel comprises the followingcomponents by weight percent: 0.05-0.15% of carbon, 0.5-1.0% of silicon, 1.0-1.5% of manganese, 0.02% or less of phosphorus, 0.010% or less of sulfur, 0.03-0.05% of aluminum, 0.0060% or less of nitrogen and the balance Fe and impurities. The preparation method of the dual phase steel comprises the following steps: performing hot rolling treatment to steel ingot, treating by subsection cooling technology and finally reeling the obtained steel. The dual phase steel of the invention has high tensile strength, good chambering performance and formability and cheap cost; in addition, the productionprocess is simple, no precious alloy element is needed to add and different strength levels can be obtained by controlling the process. The hot rolled ferrite bainite dual phase steel of the inventioncan widely and mainly used for the forming of complex shape parts such as automobile wheels, suspension parts and the like.

Description

technical field [0001] The invention relates to a high tensile strength steel and its preparation process, in particular to a hot-rolled ferritic bainite dual-phase steel with a tensile strength of 490 MPa and the preparation of the hot-rolled iron by segmental cooling after hot rolling. Method for bainitic dual-phase steels. Background technique [0002] In recent years, people have paid more and more attention to environmental protection issues, and put forward higher requirements for energy saving and emission reduction for vehicles and other vehicles. To achieve this goal, one of the commonly used methods is to reduce the weight of automobiles as much as possible while maintaining their safety performance, which promotes the application of various high-strength steels in automobiles. For example, the car chassis, wheels, and their surrounding parts account for more than 25% of the total weight of the car body, and they are mainly made of hot-rolled steel plates (such as...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/06C21D8/02B21B37/74
Inventor 季长恩杨瑞青纪云航李化龙李冉
Owner INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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