DE690469C - Manufacture of such wear-resistant objects, such as toothed wheels, which must have a high surface hardness achieved through carburization and quenching with sufficient core strength - Google Patents

Description

Manufacture of such wear-resistant items as gears that a high surface hardness achieved by carburizing and quenching with sufficient . Must have core strength 'The invention relates to the use of an known steel as case-hardening steel, namely for the production of such objects, the high surface hardness achieved by carburizing and quenching at a have sufficient core strength.

It is already known that steels with a nickel or chromium content to be used with i ° / o and below as case-hardening steel. These steels are for uses where there are high loads, useless because the strength to be achieved and toughness are not enough.

Another well-known proposal is to add high nickel and high chromium contents, with the highest nickel content being the lowest chromium content is associated with creating a steel that, after case hardening, does not have any quenching treatment requirement. Steels of this type have not proven themselves in practice because of the danger insufficient hardness of the surface is too great.

Up to now it has been customary to use chrome-nickel case-hardening steels which have a nickel content of about 2.5 % with a chromium content of 0.75 %. These steels have relatively low core strength. For purposes where particularly high stresses exist, it has hitherto also been considered necessary to use steels which have 3.5% to 4.5 ° C. nickel with a simultaneous chromium content of 0.75 to about 1% .5%. These steels have the disadvantage that if the core strength is sufficient, the high nickel content gives them a surface layer which does not always meet the requirements with regard to hardness. This disadvantage is particularly noticeable if such steels are to be used for the manufacture of gears and similar machine parts that are subject to high wear and tear. On the other hand, the high nickel content has hitherto been considered expedient '' in order to achieve sufficient core strength.

The invention is intended to eliminate the disadvantage of the steels mentioned will. It has surprisingly been found that sufficient ones Core strength can be achieved by increasing the chromium content, then at the same time the nickel content is reduced accordingly. In this way one achieves on the one hand sufficiently high core strength! ' and on the other hand due to the reduced @ g :: nickel content and at the same time the increased: chromium content a considerable increase in the surface hardness the shift.

In contrast to the steels used previously, the Invention to be used steel with a carbon content of about o, io to o, 2o % a chromium content of 1.5 to 2.5% and a nickel content of 1 to 2.5%. Expediently, molybdenum is added up to about 0.3% to the composition, as a result of which the temper brittleness is reduced and the toughness is increased. The rest of the alloys consists of iron with the usual contents of manganese, silicon, phosphorus and sulfur.

As an example of a steel that has proven itself particularly well, consider a Steel named with 0.15% carbon, 20% chromium, 2% nickel, 0.20% molybdenum, the rest Iron with the usual contents of manganese, silicon, phosphorus and sulfur.

For cases in which a particularly high core strength is not required is, the nickel content of the example mentioned can be reduced to 1.5%. Such steels have already been proposed for the production of armor plates which has a high surface hardness achieved by carburizing and quenching at, # "# @ n @ gender must have core strength., #) ie:, stress that occurs at the use of @k alloys for the manufacture of armor plates occur, are, however, completely different from those used as gears and similar machine parts subjected to wear can be observed.

Claims (3)

PATENT CLAIMS: i. The use of a steel with o, i to o, 2 % Carbon, 1.7 to 2.5% chromium, 1.5 to 2.5% nickel, the remainder iron for production such wear-resistant items, such as gears, which one by carburization and Quench achieved high surface hardness with sufficient core strength have to. 2. The use of a steel of the composition according to claim i, the however, the remainder besides iron still contains up to 0.3 0f, molybdenum, for the purpose according to claim i. 3. The use of a steel with i o, 1 5 0jo carbon, 2 01, chromium, nickel 2010, o, 2o% molybdenum, balance iron for the purpose according to claim.