US1941101A

US1941101A - Process for producing a steel having a lesser tendency to blue fracture and brittleness due to ageing

Info

Publication number: US1941101A
Application number: US497072A
Authority: US
Inventors: Meyer Hans
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-12-21
Filing date: 1930-11-20
Publication date: 1933-12-26
Anticipated expiration: 1950-12-26

Description

Q Patented Dec. 26, 1933 PATENT OFFICE PROCESS FOR PRODUCING A STEEL HAV- ING A LESSER TENDENCY T BLUE FRAC- TURE AND BRITTLENESSDUE TO AGEING Hans Meyer, Duisburg-Hamborn, Germany No Drawing.

Application November 20, 1930,

Serial No. 497,072, and in Germany Decembe' 3 Claims. (01. 143-12) 0 greatly toughen the steel, and to preserve the effect attained.

Other objects and the particularly advantageous features of my invention will appear more fully in detail hereafter, as the specification proceeds.

' When using soft kinds of ingot steel for various purposes, either in the shape of plates, tubes, rods and sectionmaterial or wire, the possibility of the occurrence of brittleness due to ageing or of blue-fracture is always a danger which considerably reduces the value of the steel for its purpose of use. Both phenomena are of a similar nature. They are recognizable chiefly by a great brittleness of the steel and they can occur if the steel has been stressed at room temperature and then allowed to stand a certain time or has been heated to 200 to 300 C. after the stressing, however also if the steel has been stressed at about 200 to 300 C.

In my prior United States Patent No. 1,843,456, filed November 21,1927, it is mentioned that a steel which becomes brittle and liable to fracture, owing to the treatment above described,

. loses this bad property to a considerable extent if it is annealed after a preliminary uniform cold deformation in such a manner that its original toughness is reestablished but the crystallographic direction effect caused by the cold deformation, that is a crystal arrangement in a certain direction, remains. This condition is not only indicated by the existing toughness of the steel, but it does not again lose its toughness, if it is subjected to a fresh ageing treatment, which in the ordinary way would produce brittleness.

It has been found, that this condition of toughness of the steel retaining the crystallographic direction effect caused by cold deformation can be produced without the necessity of annealing the steel in a particular manner. This object is also obtained without subsequently treating the steel during the process of production, if contrary to the ordinary rule it is strongly worked whilst still at temperatures between its.

As the object of this treatment is to produce a pronounced crystallographic direction efiect in the steel which can be proved crystallographically or Rtintgen-spectrographically, the degree of working must be adapted to the working temperature in such a manner that with reducing temperature within the limits of its upperstable point and 700 C. the degree of working can be less. 0n the other hand a repeated treatment of the steel according to this process, if necessary reducing the final temperature of'working, is suitable for increasing the effect. In the kind of treatment of the steel herein described a subsequent treatment, for example by annealing, is not necessary; that is not to say'that the steel. under no circumstances will stand a subsequent annealing treatment. The more intensively the steel is worked while at the'same time, the lower the temperature thereof while being worked, the more Percent Carbon 0. 125 Manganese 0.53 Phosphorus 0. 018 Sulphur 0.024

possessed whendelivered a notching toughness of 22 mkg/cm and when aged still possessed a notching toughness of -5.1 mkg/cm. The bar was then subjected to an intensive forging treatment between the temperatures of 900 and 800 C. after which a test piece of the cold steel was aged exactly as above described. The notching toughness still amounted however to 18 mkg/cm.

Therefore, whereas the iron bar deteriorated by 77% through the ageing, the deterioration through the same ageing process after forging between 900 and 800 C. was only 18%.

\The above described practical manner of treating\' the steel is considered generally speaking as faulty and unpractical. It is considered as a fundamental rule, that the temperature of a heat treatment of the steel should as far as possible becarried out and finished below the A1 temperature. In those instances, in which a depassing of this low limit temperature isunavoidable on account or technical working rea-' sons, 2. strong annealing of the steel is considered absolutely essential through which the previously obtained improvement of the steel is for the greater part again lost. The kind of heat treatment of the steel hitherto general may be expressed by the following rule:

A rule for the plate producer is, apart from the already known requirement of a percentage of phosphorus which is not too high, that the plate should be finish rolled in bright condition and annealed slightly above the transformation point AC3. (Formation of cracks in boiler plates by B. Strauss and A. Fry, Stahl und Eisen'1921, page 1136) Contrary to this opinion it has been possible to determine that, particularly, by working the steel below the A3 temperature to 700 without subsequent annealing treatment or with a very careful limited subsequent annealing, it is possible to considerably increase the quality and to impart an entirely new property to the steel.

What I claim, is:

1. A process for continuously producing from soft ingot steel, a steel with greatly reduced tendency to brittleness due to ageing and blue fracture, and independently of any subsequent treatment, which consists in initially heat working said soft ingot steel in the zone above the A:

point and continuing said working down to atemperatureranging between the A; point and 700 C. adapting the degree of working to the working temperature, whereby to produce a pronounced crystallographic directional effect in the steel and attain a sufficient toughness to largely overcome-brittleness therein arising from said ageing and blue fracture.

2. A process for continuously producing from soft ingot steel, a steel with greatly reduced tendency to brittleness due to ageing and blue tracture, and independently of any subsequent treatment, which consists in initially heat working said soft ingot steel in the zone above the A: point and continuing said working down to a temperature of approximately 800 C., while adapting the degree of working to the working temperature, whereby to produce a pronounced crystallographic directional effect in the steel and attain a suflicient toughness to largely overcome brittleness therein arising from said ageing and v blue fracture.-

3. A process for continuously producing from soft ingot steel, a steel with greatly reduced tendency to brittleness due to ageing and blue fracture, and independently of any subsequent treatment, which consists in initially heat workinga suflicient toughness to largely overcome britt1e-.

ness therein arising from said ageing and blue fracture.

HANS LIEYER