800mpa grade medium-carbon high-silicon cold-rolled galvanized sheet and its preparation method

An 800mpa, galvanized sheet technology, applied in hot-dip plating process, coating, metal material coating process and other directions, can solve the problems of obvious fine grain and strengthening effect, high alloy composition alloy cost, increased production cost, etc. Guaranteed castability, improved hardenability and cost reduction

Active Publication Date: 2017-01-18
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) The chemical composition of the cast slab (weight): C 0.17%, Mn 1.75%, S 0.002%, P 0.017%, Si0.25%, Als 0.038%, Cr 0.28%, Ti 0.022%, the balance is iron and Inclusions within the allowable range. A traditional hot rolling production line is used to roll the cast billet into hot-rolled strip steel. The rolling specification of the hot-rolled strip steel is 3.5×1270mm. The main process parameters of the hot rolling process are: billet heating temperature 1040°C, soaking time 2 hours, the final rolling temperature is 865℃, the cooling adopts front-end cooling, and the coiling temperature is 642℃. The properties of the hot-rolled product are: tensile strength 649MPa, yield strength 454MPa, and elongation rate 20.5%.

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

Embodiment 2

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

[0019] (1) The chemical composition of the cast slab (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 Inclusions within the allowable range. A traditional hot rolling production line is used to roll the cast billet 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: billet heating temperature 1070°C, soaking time 2 hours, the final rolling temperature is 870°C, the front end cooling is used for cooling, and the coiling temperature is 647°C. The properties of the hot-rolled product are: tensile strength of 654MPa, yield strength of 479MPa, and elongation of 23.0%.

[0020] (2) After cold rolling, it is rolled into galvanized raw material; the thickness of cold rolling is ...

Embodiment 3

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

[0022] (1) The chemical composition of the cast slab (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 Inclusions within the allowable range. A traditional hot rolling production line is used to roll the cast billet 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: billet 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, and elongation rate 25.5%.

[0023] (2) After cold rolling, it is rolled into galvanized raw material; the thickness of cold rolling is 1.5×1250mm...

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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 a 800MPa-class medium-carbon high-silicon cold-rolled galvanized sheet and a preparation method thereof. Background technique [0002] "Lightweight" is becoming more and more important in the automotive industry because it can directly reduce fuel consumption and emissions. Data shows that fuel consumption can be reduced by 0.6%-1.0% for every 1% reduction, and energy consumption is closely related to exhaust emissions. Therefore, the lightweight of automobiles has great practical significance for energy saving and environmental protection. Due to its good strength and deep drawing properties, excellent fatigue properties, and energy absorption, dual-phase steel is suitable for manufacturing structural parts and strengthening parts. At present, with the increasing requirements for safety, the application proportion of dual-phase steel in automobiles...

Claims

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Application Information

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Patent Type & Authority Patents(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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