CH694464A5 - Steel for railway crossing points including manganese, chromium, molybdenum and nickel - Google Patents

Abstract

Steel contains (by wt.%): 0.07-0.15 carbon (C), 0.5-1.2 manganese (Mn), up to 0.5 silicon (Si), 1.2-2 chromium (Cr), 0.4-0.7 molybdenum (Mo), 2.5-3.5 nickel (Ni), up to 0.13 vanadium (V), up to 0.05 titanium (Ti), up to 0.045% aluminium (Al), 0.015 phosphor (P) and up to 0.015 sulphur (S).

Description

       

  



   



   The technical solution concerns a chemical composition of chromium-nickel-molybdenum-based steel, as used in particular for castings for the production of railway and tram crossings. Technical background



   The materials which are hitherto known and used to produce castings for railway and tram crossings are, for example, materials available (in the Czech Republic) under the trade name "13 Mn super special". They consist of iron, with 0.60 to 0.90 percent by weight carbon, 12.5 to 16.5 wt .-% magnesium, a maximum of 0.60 wt .-% silicon, at most 0.05 wt .-% phosphorus, maximum 0.03 wt .-% sulfur and 1.8 to 2.2 wt .-% molybdenum.

   Cast iron railway steel, available under the trade name "UIC 900A", consists of iron having 0.60 to 0.80 weight percent carbon, 0.1 to 0.5 weight percent magnesium, 0.80 to 1.30 weight percent % Of silicon, not more than 0.04% by weight of phosphorus, not more than 0.04% by weight of sulfur, while steel of the trade name "75 CSD VK" consists of iron with 0.45 to 0.65% by weight of carbon, 0.75% to 1.45 wt .-% magnesium, 0.10 to 0.50 wt .-% silicon, at most 0.050 wt .-% phosphorus, a maximum of 0.050 wt .-% sulfur. Steel under the trade name "85 and 95 CSD VK" contains iron with 0.60 to 0.80 weight percent carbon, 0.75 to 1.40 weight percent magnesium, 0.10 to 0.50 weight percent silicon, not more than 0.04% by weight of phosphorus, not more than 0.04% by weight of sulfur, the percentages data in each case being the maximum permitted concentration or the maximum proportion of the individual elements concerned.



   The disadvantages of "13 Mn super special" grade steel are the difficult mechanical workability, the difficult welding and fitting of worn parts, and the inability to detect defects by means of ultrasound. The drawbacks of the UIC 900A, 75 CSD VK, 85 and 95 CSD VK grade railway crossing pieces are: deep flexural rigidity, rapid wear, burr formation, low impact resistance, breakage, low hardness and short life in operation. Disclosure of the invention



   The above-mentioned disadvantages of the material especially for the production of railway and tram crossings are substantially reduced by the use of steel, which is characterized by being composed of iron with 0.07 to 0.15% by weight of carbon, 0.50 to 1, 20 wt .-% magnesium, a maximum of 0.50 wt .-% silicon, 1.20 to 2.00 wt .-% chromium, 0.40 to 0.70 wt .-% molybdenum, 2.50 to 3.50 % By weight of nickel, not more than 0.13% by weight of vanadium, not more than 0.05% by weight of titanium, not more than 0.045% by weight of total aluminum in the steel, not more than 0.015% by weight of phosphorus and not more than 0.015% by weight. -% sulfur exists.



   The advantages of this steel compared to the current technical solutions are: achieving better mechanical properties, with the limit of mechanical strength being 950 MPa up to 1300 MPa, the flexural rigidity Rp0.2 being a minimum of 750 MPa up to 915 MPa, and the impact resistance KCV is minimum 20 J / cm <2>, the hardness 290 HB to 420 HB and the conductivity (ductility) a minimum of 10%. description



   The example of the technical solution according to these documents consists of iron with a 0.140 wt .-% carbon, 0.80 wt .-% magnesium, 0.34 wt .-% silicon, 1.76 wt .-% chromium, 0.471 wt. % Molybdenum, 2.63% by weight nickel, 0.087% by weight vanadium, 0.045% by weight titanium, maximum 0.042% by weight of the total aluminum content in the steel, maximum 0.014% by weight phosphorus and 0.009% Wt .-% sulfur.



   This steel is characterized by an ultimate mechanical strength limit (Rm) of 1147 MPa, the bending stiffness limit (Rp0,2) being 915 MPa, the impact resistance value (KCV + 20 ° <>) 26 J / cm <2>, the hardness 338 HB, and the conductivity (ductility) (A5) 14.8%. Industrial application



   The technical solution can be advantageously used for cast pieces for the construction of railway and tram crossings, where a high resistance to wear is required. This steel is very fatigue-free, allows welding of good quality and good mechanical processing of the cross pieces to be produced.


    

Claims (1)

1. Steel, especially for the production of castings for railway and tram crossings, characterized in that it consists of iron with additions of 0.07 to 0.15 wt .-% carbon, 0.50 to 1.20 wt. % Of magnesium, not more than 0.50% by weight of silicon 1.20 to 2.00% by weight of chromium, 0.40 to 0.70% by weight of molybdenum, 2.50 to 3.50% by weight Nickel, not more than 0.13% by weight of vanadium, not more than 0.05% by weight of titanium, not more than 0.045% by weight of total aluminum in the steel, not more than 0.015% by weight of phosphorus and not more than 0.015% by weight of sulfur ,