FR2654115A1 - IMPLEMENTING A CHROME MARTENSITIC STEEL FOR MEAT GRINDER KNIVES. - Google Patents

Abstract

Processing of a chromium steel with a martensitic structure, consisting of (% by weight): 0.7 to 0.9% C, less than 1% of Si, less than 1% of Mn, 0.5 to 1.5% Mo, 0.7-0.95%, V, 0 3-0 9%, Nb, 12.1-13.9% Cr, the remainder being Fe, including impurities related to the production process, for the manufacture of cutting knives.

Description

A 1 - The invention relates to the implementation of a resistance steel

  high, tough and resistant to corrosion, for

  the manufacture of cutting knives.

  Cutting knives are used to cut meat. Suitable steel for cutting knives must have a well-defined range of properties. This includes:

  good resistance to corrosion against liquid

  tissue that comes out when cutting the meat (solu-

saline),

  great hardness to ensure the resistance of the tran-

song,

  a great resistance to support the central forces

  fugitives that appear at rotation speeds of

  4,000 rpm, good wear resistance to overcome long enough time without regrinding, sufficient toughness to cut even harder pieces, for example frozen, good polishing ability to give good optical impression, with

  a possibility of manufacturing at a price as favorable as

as much as possible.

  2 - For the manufacture of knives, it has been known for a long time, namely for more than 50 years, stainless steel chromium steels martensitic structure, containing 0.2 to 2.5% C, 8 to 22 % Cr, as well as the usual contents of manganese, silicon, phosphorus, sulfur and nitrogen, as well as 0.2% to 6% molybdenum and / or tungsten (DE-PS 1 59 794) An example of this is a steel containing about 1% of C, 0.5% of Mn, 0.24% of Si, 13% of Cr, 1% of Mo and 0, 14% of N is known from DE-AS 17 52 655 of steels having a similar composition, for cutting tools, having additional levels of carburizing elements which are

  vanadium, titanium, tantalum, niobium and zirconium

  nium, in a total amount of up to 2%. For example, steel containing 0.6% C, 1% Si, 0.36% Mn, 10.5% Cr, and 1.0% can be used. of Mo This steel

  known contains at least 20% residual austenite.

  For the specific implementation for cutting knives, DE-OS 33 39 904 mentions a three-layer steel, in which either a hard core layer is disposed between two stubborn layers, or a tenacious core layer is disposed between two hard layers, which

  are assembled by rolling. For the different

  layers, steels with a chromium content

  relatively high, ie 14 or 18% of Cr

  it has a relatively low carbon content of about 0.1%. The carbon content of the hard layer is about

  1% In addition to the usual levels of silicon and manganese

  less than 1%, these steels may contain at each

  1 to 2% molybdenum and 1 to 2% vanadium.

  The object of the invention is to provide a steel for cutting knives, which, with regard to the above-mentioned properties, presents optimum values with a cost

advantageous manufacturing.

  This problem is solved according to the invention in that a martensitic steel containing 0.7 to 0.9% C, less than 1% Si, is used.

less than 1% of Mn, -

  0.5 to 1.5% Mo, 0.7 to 0.95% V, 0.3 to 0.9% Nb, 12.1 to 13.9% Cr, the remainder being iron, including impurities related to the production process,

  for the manufacture of cutting knives.

  A steel of this type, containing on average 0.80% C, 0.50% Si, 0.45% Mn, 13.0% Cr, 1.3% Mo, 0.90% V and 0.70% Nb has proved particularly suitable for cutting knives. The reason is that the steel to be used according to the present invention,

  compared to the steel used until now, the material used

  No. 4153, excellent corrosion resistance,

  because of its higher molybdenum content and the ef-

  niobium grain refining process.

  primary niobium bures, in the form of a thin phase

  dispersed, cause great resistance to wear,

  joint with secondary carbides pre-precipitated during the income.

  The manufacture of steel is customary

  The hot-rolled and then the cold-rolled strips are then formed into cutting knives. The knives are abruptly cooled down after the austenitization at a temperature of between 1050.degree.

  1100 'C, to produce the martensitic structure, at a temperature of

  quenching, and then subject to an income at a tempera-

  between 460 and 560 ° C in order to obtain a

  hardness, toughness and optimum corrosion resistance

  males. According to this, the following properties can be obtained. With a substantially similar hardness, the steel to be used according to the invention has, because of its finer and more homogeneous carbide formation, a greater tenacity of 15 to 25% (see FIG.

  alternating bending tests, there is a limit of

  fatigue strength for repeated efforts which is greater than

  than 50%, the cutting time of highly stressed cutting knives can be significantly increased in

  the salt spray test, we obtain a corro-

  sive which is significantly less with steel to put in

  according to the invention with comparative steel, the material

1 4153.

Claims (2)

  1 Use of a chromium steel with a martensitic structure, consisting of (% by weight): 0.7 to 0.9% of C, less than 1% of Si, less than 1% of Mn, 0.5 at 1.5% Mo, 0.7 to 0.95% V, 0.3 to 0.9% Nb, 12.1 to 13.9% Cr, the balance being Fe, including impurities related to the production process,   for the manufacture of cutting knives.   2 Implementation of a steel according to the claim   1, containing 0.80% C, 0.50% Si, 0.45% Mn, 13.0% Cr, 1.3% Mo, 0.90% V, and 0.70%. of Nb, the   remainder being -Fe, for the application according to the claim 1. *