US2018417A - Rail vehicle axle journal brass - Google Patents

Description

Patented a. 22, 1935 UNITED STATES PATENT OFFICE No Drawing. Application August 0. 1m. sci-m No. 884,464. In Germany August 12, 1932 To copper alloys having a comparatively high lead content, more particularly to those having percentages 01' lead within the limits 0! 10%-30% by weight, there has hitherto been given a comparatively high admixture of tin, because the view has been held that the anti-friction properties of such bronzes are principally conditional on the admixture of tin. Tin however possesses i the disadvantage which was recognized very soon, of favouring block segregation. Thus meltingshaving 30% lead by weight, 5% tin by weight and copper as the remainder, even when cooled down as quickly as possible'in ingot moulds produced pronounced block segregation, quite apart from the fact that in most cases pronounced formations of stannic acid were to be observed which in consequence of their extraordinarily great hardness preclude the use of such alloys as bearing bronzes. By alloying therewith nickel, antimony and similar admixtures, it is true it was possible to do away with the segregation dit- -ficulties to a certain extent. Other methods for reducing the block segregation were the employmentof special slag-mixtures and the observance of certain instructions relating to the melting and pouring operations.

The present invention emanates from realizing that the above-mentioned difllculties cannot be completely removed by adoptingthe measures hitherto known. New systematicresearch has revealed that'manganese is an element which influences in the most favourable manner the antifriction properties of the lead-bronzes and as regards segregations behave substantially more favourably than tin, and is consequently to be regarded as the medium which is best suited as a hardening and improving admixture for the lead-bronzes. It was established that it is possible by introducing manganese to produce highpercentage lead-bronzes even without the admixture of nickel. In particular it was found that copper alloys having a lead content within the limits of 10%-30% could be melted, withoutthe occurrence of segration, if admixtures of v manganese between 1.5% and 7% were added.

Further research even showed that the 'de-segre-- gating effect 01' the manganese is so great that without hesitation a tin content of from 1% to 6% maybe realized; moreover a phosphorus content up to 1% has proved to be advantageous.

An alloy formed in accordance with the present invention, and which has possessed in practice particularly good running qualities, is characterized by containing lead 20% by weight, man- I ganese 1.5% by weight, tin 4.7% by weight, phosphorus 0.3% by weight, copper 73.5% by weight. An admixture of manganese in lead bronzes is, in itself, not new. Hitherto however the manganese in addition to phosphorus has been added 10 merely as a de-oxidizing agent and not as a material constituent of the-alloy: consequently the manganese content when it was added for the purpose of deoxidization, was always less than 1.5% in the case of which percentages the de-segregating action of manganese is absent. Accurate research was first necessary to determine this property of manganese, especially as in the literature on this subject, a caution is, on principle, given against employing manganese 20 in lead-bronzes because, as stated, it impairs the casting properties of the alloy and debases the running and anti-friction qualities. Moreover, even if manganese has been'proposed as an admixture for bronzes which do not contain lead, 35 more particularly, in combination with preponderating percentagesof tin and of nickel, these proposals do not disclose anything as regards the favourable influence of manganese in enhancing the anti-friction qualities and as regards its iavourable behaviour in the matter of segregation. In order to be able to ascertain this peculiar suitability it was necessary, in the first place, to obtain the knowledge which has led to the present invention and which was based on the final results of comparatively lengthy research.

It is within the scope of the present invention for certain admixtures, such as, for example, sodium, calcium, lithium, barium, antimony and zinc, to be added, without anything in the iundamental properties of the new alloy being altered.

- What I claim is:- 1

Rail vehicle axle journal brass, comprising 1.5 to 7% manganese by weight and lead-bronze as the remainder, the said lead-bronze containing from 10 to 30% lead by weight and copper as the remainder.

WALTER lEYINGHAUS.