800-MPa medium-carbon high-silicon cold-rolled galvanized sheet and preparation method thereof

An 800mpa, carbon-high-silicon technology, applied in hot-dip plating process, coating, metal material coating process, etc., can solve the problems of high cost of alloy composition, obvious fine grain and strengthening effect, large amount of alloy addition, etc. Achieve the effects of improving hardenability, ensuring castability, and solving rolling difficulties

Active Publication Date: 2015-01-07
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Higher alloy composition will lead to higher alloy cost, and at the same time, it is more difficult to make steel. Due to the high alloy composition when casting with other products, the mixed billet can only be reduced to waste.
This results in a serious increase in production costs
At the same time, the amount of alloy added is too large, the effect of fine grain and strengthening is obvious, resulting in high hot rolling performance, so cold rolling is difficult

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Example 1: The 800MPa grade medium-carbon high-silicon cold-rolled galvanized sheet is prepared by the following process steps.

[0016] (1) Chemical composition (weight): C 0.17%, Mn 1.75%, S 0.002%, P 0.017%, Si 0.25%, Als 0.038%, Cr 0.28%, Ti 0.022%, the balance is iron and allowable inclusions in the range. The billets are rolled into hot-rolled steel strips using a traditional hot-rolling production line. The rolling specification of the hot-rolled strips is 3.5×1270mm. The main process parameters of the hot-rolling process are: billet heating temperature 1040°C, soaking time For 2 hours, the final rolling temperature was 865°C, the cooling was front-end cooling, and the coiling temperature was 642°C. The properties of hot-rolled products are: tensile strength 649MPa, yield strength 454MPa, elongation 20.5%.

[0017] (2) After cold rolling, it is rolled into galvanized raw materials; the thickness of cold rolling is 1.2×1250mm, and the compression ratio is 65.7%....

Embodiment 2

[0018] Example 2: This 800MPa grade medium carbon high silicon cold-rolled galvanized sheet is prepared by the following process steps.

[0019] (1) Chemical composition (weight): C 0.19%, Mn 1.81%, S 0.003%, P 0.017%, Si 0.28%, Als 0.036%, Cr 0.30%, Ti 0.021%, the balance is iron and allowable inclusions in the range. The billets are rolled into hot-rolled steel strips using a traditional hot-rolling production line. The rolling specification of the hot-rolled strips is 4.0×1270mm. The main process parameters of the hot-rolling process are: billet heating temperature 1070°C, soaking time For 2 hours, the final rolling temperature is 870°C, the cooling adopts front-end cooling, and the coiling temperature is 647°C. The properties of hot-rolled products are: tensile strength 654MPa, yield strength 479MPa, elongation 23.0%.

[0020] (2) After cold rolling, it is rolled into galvanized raw materials; the thickness of cold rolling is 1.5×1250mm, and the compression ratio is 62.5...

Embodiment 3

[0021] Example 3: The 800MPa grade medium carbon high silicon cold-rolled galvanized sheet is prepared by the following process steps.

[0022] (1) Chemical composition (weight): C 0.16%, Mn 1.90%, S 0.010%, P 0.012%, Si 0.30%, Als 0.028%, Cr 0.22%, Ti 0.050%, the balance is iron and allowable inclusions in the range. A traditional hot rolling production line is used to roll the cast slab into hot-rolled strip steel. The rolling specification of the hot-rolled strip steel is 4.0×1270mm. The main process parameters of the hot rolling process are: slab heating temperature 1000°C, soaking time 1.5 hours, the final rolling temperature is 850°C, the cooling adopts front-end cooling, and the coiling temperature is 665°C. The properties of hot-rolled products are: tensile strength 647MPa, yield strength 453MPa, elongation 25.5%.

[0023] (2) After cold rolling, it is rolled into galvanized raw materials; the thickness of cold rolling is 1.5×1250mm, and the compression ratio is 66%....

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Abstract

The invention discloses an 800-MPa medium-carbon high-silicon cold-rolled galvanized sheet and a preparation method thereof. The method comprises the following steps: hot rolling, cold rolling and galvanizing. The sheet comprises the following components in percentage by weight: 0.16-0.20% of C, 1.6-2.0% of Mn, at most 0.010% of S, at most 0.020% of P, 0.05-0.30% of Si, at least 0.025% of Als, 0.20-0.30% of Cr, 0.010-0.050% of Ti, and the balance of Fe and inclusions within allowable range. The contents of carbon and silicon are properly enhanced, and proper amounts of titanium and chromium are added. Compared with the low-carbon alloy formula by adding molybdenum and chromium, the cost is obviously reduced, and the production difficulty is lowered; and on the premise of enhancing the carbon content and silicon content, the galvanizability of the galvanizing technique is ensured. The enhancement of the contents of carbon and silicon and addition of proper amounts of titanium and chromium mainly aim to enhance the hardenability of steel and lower the Ac3 line, so that the CCT curve of steel shifts rightwards, and the Bs and Ms transition temperature is lowered. The method prevents all austenite from being converted into bainite, and ensures the martensite ratio in the galvanized product to be higher than 15%.

Description

technical field [0001] The invention relates to a cold-rolled galvanized product and a preparation method thereof, in particular to an 800MPa-grade medium-carbon and high-silicon cold-rolled galvanized sheet and a preparation method thereof. Background technique [0002] "Lightweight" is getting more and more attention in the automotive industry because it can directly reduce fuel consumption and reduce emissions. Data show that for every 1% reduction, fuel consumption can be reduced by 0.6%-1.0%, and energy consumption is closely related to exhaust emissions. Therefore, automobile lightweight has great practical significance for energy saving and environmental protection. Due to its good strength and deep drawing performance, excellent fatigue performance, energy absorption and other characteristics, dual-phase steel is suitable for manufacturing structural parts and reinforcements. At present, with the higher and higher safety requirements, the application proportion of d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/38C21D8/02C23C2/40C23C2/06
CPCC22C38/02C22C38/04C22C38/14C22C38/18C23C2/06C23C2/40
Inventor 李建英于世川孙力杨杰弓俊杰韩冰周雪峰田秀刚杨丽芳王春平刘大亮王健张斌杨青史文
Owner HEBEI IRON AND STEEL
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