DE239080C - - Google Patents

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PATENT OFFICE.

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- JV £ 239080 CLASS 18c. GROUP

and similar items.

Patented in the German Empire on September 22, 1907.

The previous information on the production of steel for armor plates is within very wide limits and relates to types of steel, which partly by cementing a particularly hard surface / partly one over theirs whole mass obtained homogeneous hardening. This homogeneous hardening is, however, not the case . strong; that the brittleness of the mass is too great, while on the other hand the penetration coefficient for storeys is lower than that of the cemented slab.

: The present, a method of generating of a steel for armor plates, projectiles and the like This creates an alloy within the very wide limits specified by others produce the surface of which by quenching Without cementing, it has an arbitrarily changeable hardness, with no brittleness arises in the mass, and this alloy in the appropriate to the attainment of this goal Manner which is conditioned by the knowledge of their transformation points.

It is known that the point of transformation of a steel lies where a molecular one Transformation of the metal is going on, either when it is heated or when it cools. These transformation points, which by slowing down the temperature increase in the Heating or the temperature drop in the Cooling, change according to the composition of the alloy. · ■■■ '■'. ■

The alloy according to the invention has the ability, by appropriate treatment, to the assume the following properties:

1. a fine-grained structure that is very soft and very different cold processing methods facilitated;

2. a fibrous structure, connected with a Toughness and flexibility, at least that of the non-cemented back layers of the current armor plates and the formation of cracks when shot at can be effectively avoided; >

3. a porcelain-like structure, which is similar to one of the cemented types of steel Hardness and is therefore able to smash the tip of projectiles ^

This possibility of doing without cementing offers great advantages in terms of both the cheapness and speed of production and increased delivery capacity, which result from it. In addition, there is the security that results from the satisfactory structure due to the absence of coarse grain, which would otherwise be difficult to be eliminated during production with long high heating of the metal.

The alloy which fulfills these conditions is a nickel-chromium steel with a high Content of carbon and chromium, at which

these two substances must be present in certain relative proportions.

These ratios are as follows: coal j at least 0.65 percent, at most 0.8 pro j cent, chromium at least 3 percent, at most 4 percent, nickel about 2.5 percent,

The treatment of this steel, especially for the production of armor plates, is the following:

xo i. After rolling out, the plate becomes evenly subjected to double reheating, the first between 850 and 900 ° C. and the second at about 775 ° C, i.e. at a temperature only slightly higher than the point at which the alloy is transformed by the heat. The duration of this Heating depends on the thickness of the plate, but in general the second becomes less take a long time than the first. In the state thus obtained, the metal is easy to move cut and has a very fine structure.

2. After the subsequent processing, the plate is ^{heated evenly to approximately 775 °} C. and hardened in oil. This hardening is followed by reheating to the same temperature and then water hardening after uniform reheating to 650 to 675 ^° C. This sequence of measures makes the structure fibrous in its entirety, and the rebound capacity becomes very strong.

3. One hardens finally with water by spraying the plate by using such a gradation of the temperatures that the mass retains its fibrous structure, while the bombardment side assumes a particularly hard, porcelain-like structure. For this it is necessary that the plate is ^{kept below 675 0} and that the area to be hardened is between 800 and 850 ⁰ , ie from a temperature which is noticeably above the transformation point of the alloy when heated, so that effective hardening he follows.

This gives a plate that is only hardened on one side, without cementation, and this last one Hardening of a non-cemented armor plate in the case of one that decreases from front to back Temperature allows to achieve all desirable gradations, both in terms of the hardness than the thickness of the hardened layer.

Claims (1)

Patent claim: Process for the production of a steel for armor plates, projectiles and the like surface hardening achieved without cementation, both in terms of the degree of hardness than the thickness of the hardened layer can be changed arbitrarily without affecting the toughness or flexibility of the The rest of the mass suffers, characterized in that a 0.65 to 0.8 percent carbon, 3 to 4 percent chromium and 2.5 percent nickel-containing steel and the following measures is thrown: a) a heating first substantially to a point above the transition point of the alloy (roughly 850 to 900 ⁰ C.) and then to a point slightly above the Umwandlüngspunktes (about 775 ⁰ C), a fine-grained, suitable for editing structure to reach; b) a heating after processing first little above the transition point (oil quenching to a temperature of approximately 775 ⁰ C.) and then reheat to the same temperature, and cooling in a usual manner, after heating to a temperature slightly below the transition point (approximately »650 to 675 ⁰ C.) and water hardening for the purpose of maintaining a fibrous structure in the whole mass; c) water hardening at such graded temperatures that the front is heated noticeably above the transformation point of the alloy (about 800 to 850 "C.) and so on receives a particularly hard, porcelain-like structure, while the mass as a whole is at a temperature below this point is held so that it retains the fibrous structure.