TWI463017B - Enamel excellent high-forming cold-rolled enamel steel - Google Patents

Description

Highly formable cold rolled niobium steel with excellent enamel properties

The present invention relates to a tantalum steel material, and more particularly to a high formability cold rolled niobium steel material excellent in enamel properties.

The traditional reference to steel enamel sex, the most important refers to the ability to prevent and control the jumping iron. The Fishscale defect refers to the fact that after the finished steel product is fired, the enamel layer is shaped like a half-moon shape or a fish scale-like peeling, and the peeling occurrence time may appear immediately after firing, or may occur several days later. The reason for the defect is that the hydrogen atom is excessively dissolved at the time of high-temperature firing. Therefore, after cooling, the hydrogen atom is supersaturated and precipitated into hydrogen molecules, and is accumulated at the joint interface between the steel material and the crucible to form a pressure. When the joint interface cannot withstand the pressure, It will cause the enamel layer to peel off and form a jumping iron defect.

The iron jump defect is directly related to the quality of the steel sheet in the defects of the enamel product, and the related problems arising from the iron jump defect usually form a major complaint case. Therefore, when the steel sheet manufacturers produce the enamel steel sheet All must prevent and filter the jumping iron defects.

At present, the design of steel products in various countries mainly adds or adjusts the alloy content in the composition, so that the precipitates are present in the steel, and microvoids are formed in the precipitate itself and around, thereby preventing the occurrence of jumping iron defects. However, since the crucible firing temperature is as high as 800 to 880 ° C, the portion of the analyte will melt and decompose, for example, titanium carbide in carbide, ferritic carbon iron, and aluminum nitride in nitride, etc., will be lowered. Its ability to adsorb hydrogen causes the occurrence of jumping iron defects to occur.

Therefore, it is necessary to provide an innovative and progressive enamel-like high-formity cold-rolled niobium steel to solve the above problems.

The invention provides a high-formability cold-rolled niobium steel material with excellent enamel property, and the technical problem to be solved is to prevent the occurrence of jumping iron defects after the steel material manufacturing process, so as to improve the enamel property of the niobium steel material.

According to the present invention, a high-formability cold-rolled niobium steel material excellent in enamel property is calculated by weight %, and the composition includes: carbon (C): 0.008% or less; niobium (Si): 0.1% or less; manganese (Mn): 0.3 % or less; phosphorus (P): 0.015% or less; sulfur (S): 0.015% or less; aluminum (Al): 0.01 to 0.06%; oxygen (O): 0.02% or less; and refined titanium nitride (TiN) The material is prepared by combining 0.07 to 0.12% of titanium (Ti) and 0.006 to 0.015% of nitrogen (N).

The embodiments of the present invention can be more clearly understood, and the objects, features, and advantages of the present invention will become more apparent. The details are as follows.

The high-formability cold-rolled niobium steel with excellent enamel property of the invention is calculated by weight %, and the composition includes: carbon (C): an important strengthening element in the steel material, and the carbon content is too high, which may cause the steel strength to be too high, which is disadvantageous for the steel forming. Therefore, the carbon content of the present invention needs to be controlled to be less than 0.008%; bismuth (Si) is a solid solution strengthening element of steel, which can delay the precipitation of ferritic carbon iron. Preferably, the cerium content is controlled below 0.1%. Manganese (Mn): is an important solid solution strengthening element of steel. If the manganese content is too high, the steel strength will be too high, which is not conducive to the formability of the steel. Therefore, the manganese content of the present invention should be controlled below 0.3%; phosphorus (P) : is an impurity in the steel, phosphorus is easily segregated to the grain boundary, causing grain boundary embrittlement, therefore, the phosphorus content of the present invention needs to be controlled below 0.015%; sulfur (S): is an impurity in the steel, sulfur is at a high temperature Titanium sulfide (TiS), titanium carbonitride (Ti ₄ C ₂ S ₂ ), manganese sulfide (MnS), etc. may be produced, wherein titanium sulfide (TiS) and titanium carbonitride (Ti ₄ C ₂ S ₂ ) are consumed. Titanium, and manganese sulfide (MnS) is not conducive to the formability of steel, so the sulfur content of the present invention needs to be controlled It is less than 0.015%; aluminum (Al) is used for deoxidation during steelmaking. When the aluminum content is less than 0.01%, it will cause insufficient deoxidation, and when the aluminum content is higher than 0.06%, it will be detrimental to the formability of the steel. Therefore, the aluminum content of the present invention needs to be controlled to 0.01 to 0.06%; oxygen (O): to be controlled to be less than 0.02%; and the refinement of titanium nitride (TiN) intervening material: by titanium (Ti) and nitrogen (N) When combined with firing, the combination of nitrogen and titanium is good. When the firing temperature exceeds 1400 ° C, titanium nitride (TiN) is formed. However, when the titanium content and the nitrogen content are too high, coarse titanium nitride intervening material is formed, which results in poor formability of the steel. Therefore, in order to control the size of the titanium nitride (TiN) intervening material to be 1 to 5 μm, in the present embodiment, the titanium content is controlled to be 0.07 to 0.12%, and the nitrogen content is controlled to be 0.006 to 0.015%. .

The invention utilizes the refinement of titanium nitride (TiN) to mediate the high temperature stability of the material. Improve the hydrogen adsorption capacity, thus preventing the occurrence of jumping iron defects after the steel material process, thereby improving the enamelability of the steel.

The high-formability cold-rolled niobium steel of the invention is produced by a conventional continuous casting process, including hot-rolled steel coil→continuous pickling and trimming→cold rolling→continuous annealing→cold-rolling steel coil, wherein the continuous annealing line is combined with cleaning and annealing. Four functions, such as quenching and tempering, so the product homogeneity can meet the needs of the application. In addition, in the present embodiment, in the on-site casting operation, the molten steel must be operated at a suitable casting speed under a low superheat degree (below 25 ° C), and the steel blank is cooled by the intensive cooling method to refine the solidification of the steel embryo. The grain structure is obtained to obtain a uniformly refined titanium nitride (TiN) intervening material.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows an electron micrograph of a titanium nitride (TiN) intercalation material of the present invention. Figure 2 is a graph showing the results of energy dispersive spectroscopy (EDS) analysis of the nitrided titanium nitride (TiN) intervening material of the present invention. The cold-rolled niobium steel of the present invention is based on high-formity ultra-low carbon steel (Interstitial Free Steel), that is, adding or increasing the content of titanium and boron in the composition to reduce the presence of solid solution carbon and nitrogen, and then improving the appropriate Nitrogen and titanium alloys form a sufficient amount of titanium nitride, which is effective in preventing the formation of jumping iron defects after firing, as shown in Figs. 1 and 2 . In addition, as can be seen from FIG. 1, the titanium nitride (TiN) of the present invention is micron-sized and has a polygonal shape.

Formability test:

Table 1 shows the results of comparison of the properties of the cold rolled niobium steel of the present invention and the general smooth cold rolled steel (BA CQ1). As shown in Table 1, the cold rolled niobium steel of the present invention has excellent elongation and plastic strain ratio (r value), which proves that the cold rolled niobium steel of the present invention has good formability.

Enamel test:

Tested with the special glaze 2290 designed by FERRO, the glaze is similar to the glaze, and the adhesion to the steel is not better than the bottom glaze. The design of the steel is not good or the pickling operation is not easy. The occurrence of a jump iron defect can be used to test the resistance to jumping iron of the steel of the present invention. Table 2 shows the test formulations for glaze 2290.

First, after the steel is degreased, it is pickled in 10% sulfuric acid; after neutralization and drying, the glaze slurry is prepared according to the 2290 test formula (Table 2); finally, it is fired at a high temperature of 830 °C.

Table 3 shows the chemical compositions of Inventive Examples 1 to 5 and Comparative Examples 1 and 2. Table 4 shows a comparison of the enamel test results of Inventive Examples 1 to 5 and Comparative Examples 1 and 2. As shown in Tables 3 and 4, the present invention appropriately improves the composition of the nitrogen (N) and titanium (Ti) alloys, and can indeed strengthen the steel resistance to jumping iron. On the other hand, as a comparative example, the general bright-faced cold-rolled steel (BA CQ1) and the general ultra-low carbon steel (IF CQ2) are all formed after the test. Defects prove that the two are not suitable for enamel use.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the scope of the present invention. The scope of rights of the present invention should be as described later. The scope of the patent application is listed.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing an electron micrograph of a titanium nitride (TiN) intercalation material of the present invention; and Fig. 2 is a graph showing an energy dispersive spectroscopy (EDS) analysis result of a Titanium nitride (TiN) intercalation material of the present invention.

Claims (3)

A high-formity cold-rolled niobium steel with excellent enamel properties, calculated by weight %, comprising: carbon (C): 0.008% or less; niobium (Si): 0.1% or less; manganese (Mn): 0.3% or less; phosphorus ( P): 0.015% or less; sulfur (S): 0.015% or less; aluminum (Al): 0.011 to 0.06%; oxygen (O): 0.02% or less; and refined titanium nitride (TiN) intervening substance: 0.07 Titanium (Ti) of 0.12% and nitrogen (N) of 0.006 to 0.015% are combined and fired, wherein the titanium nitride (TiN) is sintered at a temperature of 1400 ° C or higher. The high-formability cold-rolled niobium steel of the enamel property of claim 1, wherein the titanated titanium nitride (TiN) has a size of 1 to 5 μm. The high-formability cold-rolled niobium steel having the excellent enamel property of claim 1, wherein the titanated titanium nitride (TiN) is a polygonal type.