DE1247670B - Use of steel as a material for objects to be coated with glass - Google Patents

Description

Use of steel as a material for objects to be coated with glass Previously, steel suitable for coating with glass contained titanium in an amount of 4.2 to 17.5 times the carbon contained in the steel. This addition of titanium was made for the purpose of increasing the great affinity of titanium non-metallic elements, e.g. B. Oxygen, nitrogen and carbon, like them usually contained in steel as an oxide; To bind nitride and carbide. at the heating of the steel during the glass coating can therefore lead to the development fine pores or bubbles caused by escaping carbon monoxide or nitrogen gas effectively prevented.

The production of such a steel, however, has numerous disadvantages connected because the titanium content through oxidation and reaction with the slag and the refractory furnace lining is reduced. That way it's difficult to adhere to a specific titanium target.

Furthermore, the addition of titanium increases the flowability of molten Steel reduced considerably. As a result, the refractory furnace lining is subject heavy wear. The molten steel is in this way with macroscopic contaminated with non-metallic inclusions.

To solve this problem, according to the invention, a steel is made up of 0.05 to 0.410 / o carbon, 0.052 to 0.63% manganese, 0.25 to 0.29% silicon, 0.15 to 0.7611 / o niobium , 0.006 to 0.007% phosphorus, 0.010 to 0.012% sulfur, the remainder iron, used as a material for objects to be coated with glass. The ratio of niobium to carbon preferably has a value between 3 and 6.8: Steels are known which are in a similar alloy range and can also contain niobium. For example, from French patent 822 446, a niobium steel is known which contains 0.02 to 1%, preferably 0.05 to 0.25% niobium, as a result of which the grain fineness is improved. These steels can contain up to 1% carbon, 2% manganese, 1% silicon as well as chromium, molybdenum and nickel. About the properties is only indicated that with niobium contents up to about 0.10 / 0 the yield strength and the breaking load are improved and the ductility is at most slightly changed, while with niobium contents above 0.1% breaking load and yield strength are reduced and the ductility is considerable is increased. About the relationship between the content of niobium and carbon it is stated that with a carbon content of 0.1% the niobium content should also be about 0.1%. When the carbon content increases to 0.15%; the niobium content must also rise to about 0.1511 / o. With a further increase in the carbon content to about 0.35%, however, the niobium content decreases relative to this to 0.18% "that is to a little more than half of the carbon content, and then decreases further to half at a carbon content of 0.5%, namely to about 0.25% niobium. As the carbon content increases, the ratio of niobium to carbon falls from about 1: 1 to about 0.5: 1, based on weight.

From the German Auslegeschrift 1019 674 steels are with about 0.05 up to 0.12% carbon, 0.30 to 0.65% manganese, 0.15 to 0.35% silicon and also except Iron and minor impurities at least one strong carbide former in such Quantities that the stoichiometric ratio of the carbide formulas by at least the Under half -is known as materials for enamelled objects. As carbide formers Ti, V, Be, Zr, Ta, Nb and B are mentioned, but -that Emphasis is placed above all on Ti. The requirement that the stoichiometric -Ratio of the carbide formula is undercut by at least half; means for niobium, a maximum of 3.8 parts by weight of niobium per part by weight carbon which means that these steels could contain about 0.18-0.45% niobium. However, there is no difference whatsoever between the various carbide formers made, apart from the preferred mentioned titanium. The preferred ones shown Steels are titanium alloy steels and do not contain niobium, whereby the ratio of Titanium to carbon is about 2 to 1.5: 1 to 1: 1 by weight. For niobium, it would be just under twice the weight, i.e. about 3.8 to 3: 1 to 2: 1.

Both known steels apparently contain neither sulfur nor phosphorus; and from none of the literature it can be inferred that not a far below The maximum content of niobium corresponding to the carbide ratio, but an approximate amount for the carbide ratio or even higher niobium content is to be used so that steels are produced, which are particularly suitable for coating with glass. The teaching of the two References is just in contrast to the teaching of the invention, since after the known prior art, a better result can be expected at low niobium contents than the higher niobium contents according to the invention, the best above that half the carbide ratio or even up to twice this ratio.

The use according to the invention of the special niobium steel offers the possibility of the known disadvantages of the. Titanium steels; the one hand in the difficult production and on the other hand in frequent quality defects in. Product justified are to be avoided without affecting the suitability of the steel for coating glass will.

The production of the steel used according to the invention can be carried out in a conventional manner Wise done <. Unlike titanium, when it comes to steel making, it is practical no niobium loss, so that easily one. certain niobium target must be adhered to. The drawing explains the invention.

F i g. 1 is a graph of glass coatability of the steel used according to the invention as a function of the niobium content; F i g. 2 Figure 3 is a graph of glass coatability. depending on the ratio % Niobium to% carbon in steel; F i g. 3 shows the bubbles in the one The sample subjected to the blistering test was produced.

In the following Table 1- the compositions of the steels denoted by numbers in FIGS. 2 and 3 are given. These are ten castings of about 20 kg each, which were made using Ferroniob with the following composition: C. . .... 0.021% Mn ....... 0.080 / 0 Si ...... 0.77% P ........ 0.086.1 / o S ....... 0.054 ° / o - Nb ...... 66.890% Ta ...... 2.10% Fe ....... remainder The amounts of alloy additions are given in Table 1. Table 1 4110 C ofo Mn ° / a Si (% r I Ofo s vo Nb (Nb: C 1 0.12 0.59 0.26 - 0.006 - -0.011 0.76 6.3- 2 0.24 0.63 0.25 0; 006 0.012 0.73 3; 0 3 0.41 0.60 0.27 0; 007 02-012 0.71 1.7 4 0.12 0.57 0.24 0.006 0.012. 0.16 1.3 5 0.24 __ 0.58 0.25 0.007 0.012 _ 0.15 0.6 - 6 0.40 0.60 0.26 0.006 - 0.012 0.20 0.5 7 0.06 0.54 0.28 0.006 0.012 - 0; 32 5.3 8 0.05 0.52 0.29 0.006 0.012 0.33 6.6 9 0.06 0.56 0.28 0.006 0.010 0.18 3.6 10 0.05 0.53 0.28 0.006 0.010- 0.20 4.0 A portion of each of these ten different castings was forged at a forging ratio of 5 to 30 mm in diameter and then rolled into sheets 3.2 mm in thickness. Test pieces measuring 100 X 100 X 3; 2 mm were cut from these sheets and tested for their ability to coat the glass, in particular the formation of bubbles. First, each sample was tempered for 1 hour at 900 ° C and then sand blasted. A single coat of white antimony enamel frit was then applied as a glass coating and the whole was baked for about 8 minutes at a temperature of 800 ° C. The formation of bubbles was then examined. This test determines the amount of blistering. -The less the bubble formation, the better the glass coatability. Like F i g. 3 shows, the samples show fewer and fewer bubbles with increasing niobium content. Sample I corresponds to a steel with no niobium content and shows many bubbles, while samples II and III show little or no bubbles. Usually, the number of bubbles increases with the amount of carbon contained in the steel, but in the case of a steel containing niobium, with a practically constant carbon content, the number of bubbles is considerably reduced the higher the niobium content. F i g. 1 shows these relationships in a graph using the ten different samples from Table 1. The numbers given in the curves in FIG decreases as the ratio of niobium to carbon increases. If this ratio exceeds the number 3, useful results are already achieved. If this ratio is above 6, no more bubbling is observed at all. These relationships are shown in FIG. 2 shown schematically. Thus, if niobium is added to steel in such an amount that the niobium-to-carbon ratio is more than 6, the formation of bubbles is always prevented and excellent glass coatings are obtained. In the above example, a single coating was used to produce the glass layer, but multiple successive layers can be applied, as is common in the art, to minimize the occurrence of bubbles.

As little blistering as Samples 2 and 9 this one Example whose niobium-carbon ratio is in the order of 3 (see Sect. F i g. 3, sample 11), practically does not interfere. In other words it can be said that it is possible by selecting a niobium to carbon ratio at 3 or above is to reduce the number of coatings required by half, so that the Productivity can be increased considerably.

It should also be pointed out that, because of its better thermodynamic behavior, niobium does not lead to oxidation losses when the niobium-containing steel is melted, so that the yield reaches almost 100%. Thus, it is easy to control or predict the niobium content of a molten steel, and there are no difficulties in producing the steel of the present invention as in the production of titanium steel. In addition, as shown in Table 2, the purity of the steel is excellent, and the occurrence of sand marks shown by the planing test is much lower with niobium than with titanium. Table 2 Number of sand marks Low carbon Nb-Nb used purity Steel additive in steel Nb- (old process) 01 to>0.5>1.0> 1.5 Proportion of JSPS) 0 @ 5 mm to up to> 2.0 mm (%) (° / o) (° / o) (° / o) 1.0 mm 1.5 mm 2.0 mm C: <0.07 7 0.3 0.32 107 A1 .... 3 @. 1 1 0 0 0 B 2 .... 2 to 5 #t Mn: 0.30 to 0.60 8 0.3 0.33 110 A 1 .... 2 to 3 #L 0 1 1 0 0 B2 .... 3 to 4 # t Si: 0.15 to 0.30 9 0.2 0.18 90 A1 .... 2 to 3 #t 2 0 0 0 0 B 2 .... 2 to 3 g, - P: <0.03 10 0.2 0.20 100 A 1 .... 2 to 3 w 1 1 0 0 0 B2 .... 2 to 4it S: <0.03 The following example relates to a niobium-containing steel made using niobium oxide.

During the reduction period of steel production in a basic 10-ton electric furnace and after the slag had been completely converted into a white slag, a mass consisting of a controlled mixture of niobium pentoxide and reducing agent (calcium silicide, silicon, ferrosilicon, etc.) was added to to achieve the various niobium concentrations given in Table 3. This table also shows the composition of the various niobium-containing steels produced in this way. Table 3 Nb addition ° / Nb Nb: C o / 'C ° / o Mn% Si o /' P ° / o S Nb205 o / o Nb (kg / t) 11 0.10 0.58 0.27 0.006 0.011 9.15 0.64 0.62 6.2 12 0.08 0.61 0.28 0.006 0.012 7.87 0.55. 0.54 6.8 The analysis of the niobium-containing steel produced by this addition process shows that not only is the proportion of niobium used in the steel extremely high, but that the niobium is also incorporated in a uniform distribution. The purity and glass coatability of the resulting steel are comparable to those of the steels obtained by adding ferroniobium according to the above example.

Claims (2)

Claims: 1. Use of a steel, consisting of 0.05 to 0.41% carbon, 0.52 to 0.63% manganese, 0.25 to 0.29% silicon, 0.15 to 0.76 niobium, 0.006 to 0.007% phosphorus, 0.010 to 0.012% sulfur, the balance iron, as Material for objects to be coated with glass. 2. Use of a steel according to claim 1 ,. the ratio Nb: C being between 3 and 6.8, for the Purpose according to claim 1. Considered publications: German Auslegeschrift No. 1019 674; B. Hab b e l, »Iron and Steel Alloys«, 2nd Supplementary Volume, 1. Part, 1940, p. 275, No. 28.