Alloys or metallic compositions – Ferrous – Eight percent or more manganese containing
Patent
1995-09-27
1997-02-11
Yee, Deborah
Alloys or metallic compositions
Ferrous
Eight percent or more manganese containing
C22C 3838
Patent
active
056017820
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an abrasive resistant high manganese cast steel used for a knife of an ore-crusher, or shockresistant and wearresistant parts such as a caterpillar shoe for a conveying device, and the like.
BACKGROUND ART
A construction machine used for crushing various type of ores of mines, includes various types of parts such as a knife of a crusher, a caterpillar shoe for a conveying machine, a bucket knife, a rail and a rail point. The material for these parts is required to have not only a sufficient strength level as a structural member, but also an excellent abrasive resistance, a shock resistance and a corrosion resistance.
A high manganese cast steel, for example, Hadfield steel (carbon: 1-1.3 weight %, manganese: 11.5-13 wt %) has properties such as exhibiting an austenitic structure at room temperature, a low yield point, a high ultimate tensile strength, and a significant work hardening. Therefore, the hardness and the wear resistance of the steel can be increased by a cold working or surface abrasion. In general, a Hadfield steel is heated to 1050.degree. C. or higher, and then quickly cooled, to make an abrasive resistant and shockresistant tough steel, a surface portion of which has a high hardness and an inside portion of which has a high toughness.
Jap. Pat. Appln. KOKAI Publications. Nos. 54-43818, 57-39158 and 55-53513, disclose an abrasive resistant high manganese cast steel in which crystal grains are refined by adding a small amount of each of the elements for preparing a carbide, such as Ti, V, Cu, Zr, Ce, Mo, W and Nb, and another abrasive resistant high manganese cast steel in which a small amount of spherical carbide is precipitated on the base material of a high carbon-manganese steel.
However, in the former abrasive resistant high manganese cast steel, it is difficult to remarkably improve the abrasive resistance only by fining the crystal grains, and the degree of the improvement is limited.
In the latter abrasive resistant high manganese cast steel, the wear resistance can be improved to a certain degree by enhancing the precipitation of the spherical carbide. However, the austenite matrix itself is not improved but maintained as it is, and therefore it is difficult to obtain a sufficient abrasive resistance while maintaining a required level in shock resistance.
The present invention has been proposed to solve the above-described problems and the object thereof is to provide an abrasive resistant high manganese cast steel having an excellent abrasive resistance and an excellent shock resistance.
DISCLOSURE OF INVENTION
According to the present invention, there is provided an abrasive resistant high manganese cast steel characterized by containing: 1.3-1.4 weight % of C, 0.05-0.20 weight % of Si, 14.0-15.0 weight % of Mn, 0.5-1.5 weight % of Cr, 0.3-0.8 weight % of V, 0.2-0.4 weight % of Ti, and 0.5-1.0 weight % of Mo, and a balance of Fe and inevitable impurities.
The reasons for specifying the ranges of the contents of the component elements will now be described one by one.
Regarding C, the content is determined in consideration of the balance between the carbide generating element amount and the Mn content. When the carbon content becomes lower than 1.3%, the carbide is not precipitated in an amount sufficient to reinforce the matrix, resulting in an insufficient wear resistance. In contrast, when the carbon content exceeds 1.4%, the carbide is generated by precipitation in an excessive amount, thus reducing the shock resistance. This is because the toughness of an alloy steel is generally improved as the content ratio of carbon with respect to that of Mn (Mn/C ratio) is increased.
Usually, Si is added to a high carbon and high manganese steel in an amount of 0.2-1.0 weight %. The purposes of the addition of Si are to refine the bath and improve the bath flow when casting. These purposes can be also achieved by using other means to refine the bath, which results in minimizing the amount of non-metal inclusions, and therefore an exce
REFERENCES:
patent: 3556777 (1971-01-01), Petry
patent: 4039328 (1977-08-01), Novomeisky et al.
Kunioka Saburo
Toriyama Hiroshi
Shinhokoku Steel Corporation
Yee Deborah
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