High-strength hot-dip galvanized steel sheet and process for producing the same

A technology of hot-dip galvanized steel sheet and manufacturing method, which can be applied to manufacturing tools, hot-dip galvanizing process, chemical instruments and methods, etc., and can solve the problems of poor stamping formability and poor appearance.

Active Publication Date: 2010-03-31
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the increase in the strength of steel sheets generally has the following problems: the press formability is deteriorated, and deformation of about tens of microns called surface deformation occurs, resulting in deterioration of appearance.

Method used

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  • High-strength hot-dip galvanized steel sheet and process for producing the same
  • High-strength hot-dip galvanized steel sheet and process for producing the same
  • High-strength hot-dip galvanized steel sheet and process for producing the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0098] The present invention is further illustrated below by way of examples.

[0099] Steels having the chemical components of steels A to Y shown in Table 1 were melted by vacuum melting to produce billets. These billets were heated to 1200° C., hot rolled at a finishing temperature of 850° C., cooled, and then coiled at 600° C. to manufacture hot-rolled steel sheets with a thickness of 2.5 mm. The obtained hot-rolled steel sheet was pickled, then cold-rolled at a rolling reduction of 70%, to obtain a cold-rolled steel sheet having a thickness of 0.75 mm.

[0100] Table 1

[0101]

[0102] Next, the sample cut out from the cold-rolled steel sheet obtained above was held in an infrared thermography furnace (infrared image furnace) at the annealing temperature shown in Table 2 for 60 seconds, and then carried out under the conditions shown in Table 2. Secondary cooling, after hot-dip galvanizing (bath temperature: 460°C), alloying treatment (520°C×15s), secondary cooling ...

Embodiment 2

[0115] The steel with the chemical composition of steel C, D, E, G shown in Table 1 is smelted by vacuum smelting, hot rolling, pickling, cold rolling are implemented under the same conditions as in Example 1, as shown in Table 3 After holding at the annealing temperature for 60 seconds, perform primary cooling under the conditions shown in Table 3, perform hot-dip galvanizing treatment (plating bath temperature: 460°C), perform alloying treatment, and perform secondary cooling until 150°C Below the temperature, and implement surface pass rolling.

[0116] For the hot-dip galvanized steel sheet obtained above, samples were taken, and the area ratio of the martensite phase, the total area ratio of the pearlite phase and / or bainite phase were measured by the same method as in Example 1, and the tensile properties were measured. , work hardening (WH), sinter hardening (BH) and YPE1 after accelerated aging test.

[0117] The obtained results are shown in Table 3 together with the...

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Abstract

A high-strength hot-dip galvanized steel sheet that even on the premise of ordinary CGL heat cycle, has a low yield stress and excels in resistance to natural aging and baking hardenability without reliance on the use of expensive Mo; and a process for producing the same. The constituent composition thereof comprises 0.01 to less than 0.08% C, 0.2% or less Si, more than 1.0 to 1.8% Mn, 0.10% or less P, 0.03% or less S, 0.1% or less Al, 0.008% or less N and more than 0.5% Cr so that the relationship 1.9=Mn(mass%)+1.3Cr(mass%)=2.8 is satisfied and comprising the balance iron and unavoidable impurities. The structure thereof has a ferrite phase and a martensite phase of 2 to 15% area ratio, and the cumulative area ratio of pearlite phase and / or bainite phase is 1.0% or less. In the productionof this hot-dip galvanized steel sheet, the temperature and cooling rate are controlled during the annealing / plating operation subsequent to cold rolling.

Description

technical field [0001] The invention relates to a hot-dip galvanized steel sheet suitable for the fields of automobiles, home appliances, etc., low in yield stress, excellent in room temperature aging resistance and sintering hardening, and a manufacturing method thereof. Background technique [0002] In recent years, steel sheets for automobiles have been increasing in strength for the purpose of thinning steel sheets and improving safety in order to improve mileage per gallon by reducing the weight of the vehicle body. However, increasing the strength of steel sheets generally has problems in that press formability is deteriorated, and deformation of several tens of micrometers called surface deformation occurs, resulting in deterioration of appearance. [0003] In contrast, steel sheets (BH steel sheets) that are soft and easy to form during press forming and exhibit high sinter hardenability in the coating and sintering process after press forming are being developed. T...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D9/46C22C38/38C23C2/06
CPCC23C2/02C21D2211/008C21D2211/009C23C2/28C21D9/48C23C2/06C22C38/04C21D2211/005C22C38/001C21D8/0473C21D2211/002C22C38/38B32B15/013C22C38/02C22C38/06C22C38/18C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C23C2/29C23C2/0224C21D1/18C21D8/0226C21D8/0236C21D8/0273
Inventor 小野义彦木村英之奥田金晴藤田毅樱井理孝
Owner JFE STEEL CORP
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