US2035394A - Cast steel - Google Patents

Description

Patented Mar. 24, 1936 UNITED STATES PATENT OFFICEI' 2,035,394 cAs'r STEEL Russell H. McCarroll and Gosta Vennerholm,

Dear-born, Mich., assignors to Ford Motor Company, Dearborn, Mich;

WIN

a corporation of Dela- No-Drawing. Application February 9, i934, Serial No. '10,524

2 Claims. (oi. 75-125 This invention relates to a new and improved steel alloy having new and exceptional properties and capable of being employed for the casting of many articles of manufacture for which no known 5 alloys or metals could be satisfactorily employed.

1 5' intricate castings due to lack of suflicient fluidity.

Also because of the greater cost of making an ordinary steel casting of such a design it would be prohibitive, if in fact it were possible to secure sound castings in ordinary steel of such a design. so Malleable iron is especially well adapted for thin castings but cannot be welded satisfactorily because of its tendency to harden and become brittle under the high heats of the welding operation which are above the critical temperature and 25 because of the tendency of the free temper carbon content to oxidize and form gases which produce blow holes and thereby weaken the weld. Ordinary grey cast'iron could' not be successfully employed for articles of the type under consider- 30 ation because of its relatively low physical properties and'because-hlghcar'bon content thereof results in marked hardening and embrittlement of the metal in the region of the weld after welding.

35 The present invention has for its principal object to provide a new and improved steel alloy capable of being successfully cast to form thin walled castings and withstanding the high temperatures of welding operations without hardening effect or embrittlement and which, moreover, can be manufactured and fabricated at a relatively low cost.

We have found after considerable experimenta- 45 tion that a steel having an analysis falling within the following limits, will have all of the desired properties and none of the objectionable features T as above set forth, of the more commonly used materials:

0.25% (maximum) Mn 0.15 to 0.65% 7 Si [452.15% to 1.2 Cu L 0.90 toii'i5% 1 5 Fe... balance If desired sulphur up to 0.15 may be added for increasing ease of machineability.

It has been found that the presence of more than 0.25 C. results in a hardening and embrittlement of the metal in the region of the weld 5 after the metal is subjected to the high welding temperatures. I

The relatively high silicon content together with the copper results in increased fluidity which enables very thin wall castings to be satisfactorily 10 produced. The silicon or copper contents in properly combined proportions give a lower melting point whichtends to improve the welding properties of the metal. It is found that the silicon and copper go into solid solution with the iron to produce an alloy havingexcellent high physical properties; the high silicon content being important in this respect as it tends to increase the solubility of the copper, the metal having a tensile strength of from 85 to 90 thousand pounds per 20,

square inch and a Brinnell hardness of about 150. While the silicon content should be kept high enough to secure the desired fluidity, it has been found to be best not to have an amount in excess of 1.25%, because of its effect onmachineability 5 especially in combination with a relatively high copper content, o I

It has also been found advisable not to have the copper content greater than 1.75%, thereby to avoid the tendency towards excessive air harden- The metal may be cast in green sand molds thus enabling savings to be efiected in production costs. After casting an ordinary normalizing treatment is desirable, such normalizing resulting v 5 in a decided improvement in the physical proper- A ties by producing a marked grainrefinement of the metal.

. Although copper is employed the copper content is relatively small, and the production cost 40 of the metal is appreciably lower than that of either cast steel or ordinary malleable iron and possesses marked advantages over either in that it may be used for producing excellent thin wall castings, to-which other parts may be integrally secured by welding; a strong welded joint being secured without producing any deterioration of the physical properties of the metal.

Although the invention has been described from the standpoint of its-advantages when used r for the manufacture of thin wall castings, to

- which it is desired'to weld other parts, it will be understood that the invention is not to be con- Y sidered as limited to this one specific use, but that as other uses will be readily apparent to the 5g skilled metaliurgist and those in the art to which steel capable of withstanding welding temperathe invention appertains, it is the purpose to intures without deterioration or air hardening efclude herein such other uses. Iects, said steel having an analysis lying between We claim: a the following limits:

5 1. An article of manufacture a sound thin wall 5 1 casting of low carbon, high silicon steel and hav- C 025% (maximum) ing an anal 1 1 1 withi m r 11 1 11 it 055% Y3 S y Hg 11 e 0 0W 8 m S1 0 75 t 1 25% C 0.25% (maximum) (:11 0.90 to 1.75% Mn 0.15 to 0.65% Fe balance s1 0.75 to 1.25%

Cu 030 to 135% and 1: 1 wii ch th sil n a d g 2 55 1 com ne n approx ma e y e prop r ns 0 Balance substantially all iron. to 5 respectively.

2. An article of manufacture comprising a RUSSELL H; McCARROIL. 15 sound thin wall casting of low carbon, high silicon GOSTA VENNERHOIM. 15