BE507473A - - Google Patents

Description

       

   <Desc / Clms Page number 1>
 



    IMPROVEMENTS BROUGHT TO: AUSTENITIC STEELS.



   The invention relates to improvements made to austenitic steels.



   It is well known that the majority of austenitic steels are characterized by relatively low elastic and breaking strengths.



  This restrictively influences their application when high elastic strength is required together with non-magnetic properties and, in some cases, stainless qualities.



   Where it was important to have high elastic strength, along with non-magnetic properties, it was customary to cold work austenitic steels in order to impart the necessary high elastic strengths to them. However, when it comes to large parts, cold working is a difficult and expensive operation, requiring considerable skill and experience. In addition, there is still a great deal of uncertainty as to the final result obtained.



   The present invention is directed to a means of eliminating the need for cold working and substituting for it a hot heat treatment to provide the required elastic strengths. This is achieved by using an austenitic steel of specially selected balanced composition which is sensitive or responds to a practical hardening or quenching treatment by solution cooling, and precipitation. The composition selected in accordance with the invention comprises:
Carbon 0.2 -'0.7%
 EMI1.1
 Manganese 2.0. - $, 0% Nickel 8.0- 15.0%

 <Desc / Clms Page number 2>

 
 EMI2.1
 
<tb> Chrome <SEP> 2, <SEP> 0 <SEP> - <SEP> 12.0 <SEP>% <SEP>
<tb>
<tb> Vanadium <SEP> 0.3 <SEP> - <SEP> 1.0%
<tb>
 and for the rest practically iron.



   The preferred range of the proportions of the constituents is:
 EMI2.2
 
<tb> Carbon <SEP> 0.35 <SEP> - <SEP> 0.55 <SEP>% <SEP>
<tb>
<tb> Manganese <SEP> 3.0 <SEP> - <SEP> 5.0 <SEP>% <SEP>
<tb>
<tb> Nickel <SEP> 10.0 <SEP> - <SEP> 13.0 <SEP>% <SEP>
<tb>
<tb> Chrome <SEP> 2.5 <SEP> - <SEP> 5.5 <SEP>%
<tb>
<tb> and <SEP> Vanadium <SEP> 0.35 <SEP> - <SEP> 0.75 <SEP>%
<tb>
 
In accordance, the invention can be said to provide a method of producing components of austenitic steels having a high degree of elastic strength, without cold working, which comprises subjecting to solution quenching and precipitation hardening of compressed alloys. nant the balanced composition (general or of the preferred range) defined above.



   A suitable heat treatment for steels in the field of the invention consists in applying heating to 1100 -1200 C and cooling in air, oil or water (i.e. the treatment. by solution) followed by a precipitation treatment at 650 C-750 G. The invention encompasses the selected alloys and the products resulting from the heat treatment of the type indicated.



   In an example realizing the invention, the balanced composition included:
 EMI2.3
 
<tb> Carbon <SEP> 0.45 <SEP>% <SEP>
<tb>
<tb> Manganese <SEP> 4.5 <SEP>%
<tb>
<tb> Nickel <SEP> Il, 5 <SEP>%
<tb>
<tb> Chrome <SEP> 5.0 <SEP>% <SEP>
<tb>
<tb> Vanadium <SEP> 0.50 <SEP>% <SEP>
<tb>
      and for the rest practically iron.



   Using a suitable solution and aging treatment, i.e. applying 1 hour heating at 1150 C followed by abrupt cooling with water, followed by heating for 16 hours at 700 and cooling in air, the following properties were obtained at apartment temperature for the alloy of this example:

   Elongation test (0.1% elongation under load of 87.25 K / mm2 under load (0.5% elongation under load of 98.12 K / mm2
 EMI2.4
 
<tb> Maximum <SEP> load <SEP> or <SEP> of <SEP> rupture <SEP> 117.49 <SEP> K / mm2
<tb>
<tb> Elongation <SEP>% <SEP> 21
<tb>
<tb> Reduction <SEP> of <SEP> section <SEP> or <SEP> striction <SEP>% <SEP> 36.5
<tb>
<tb> Hardness <SEP> Brinell <SEP> 363
<tb>
 
The above properties are typical of the result of the application of the solution quenching and precipitation hardening treatment to alloys falling within the range of the balanced composition already indicated.



   CLAIMS.

** ATTENTION ** end of DESC field can contain start of CLMS **.


    

Claims (1)

--------------------------- 1. - A method of producing components of austenitic steels with high elastic strength, without cold working, which consists in subjecting to a hardening treatment by solution quenching, and precipitation, alloys possessing the balanced composition comprising: carbon 0.2 to 0.7%, manganese 2.0 to 8.0%, nickel 8.0 to 15.0%, chromium 2.0 to 12.0%, vanadium 0.3 to 1 % and the rest practically iron. <Desc / Clms Page number 3> 2. - A method according to claim 1, wherein the balanced alloy composition comprises: carbon 0.35 to 0.55%, manganese 3.0 to 5.0%, nickel 10.0 to 13.0. %, 2.5 to 5.5% chromium, 0.35 to 0.75% vanadium, and the rest essentially iron. 3. - A method as previously claimed, in which the balanced alloy composition comprises: carbon 0.45%, manganese 4.5%, nickel 11.5%, chromium 5.0%, vanadium 0.50 %, and the rest practically iron. 4. A method according to any one of the preceding claims, in which the heat treatment of the balanced alloy composition comprises heating to 11000-12000C and cooling in air, oil or water. (i.e. solution treatment) followed by precipitation treatment at 650 -750 C. 5. A method according to claim 3 and claim 4, wherein the heat treatment comprises heating for one hour at 1150 C and then abruptly cooling with water from this temperature (ie. (say solution treatment), followed by a precipitation treatment comprising heating for 16 hours at 700 G and cooling in air from this temperature. 6. - Austenitic steel components produced by the method according to any one of the preceding claims. 7. Austenitic steels having the balanced composition defined in any one of claims 1 to 3, for which a high elastic strength can be obtained, without cold working, by heat-hardening treatments. solution, and precipitation, of the kind described.