Structural material

Abstract

For providing a structural material having improved fatigue strength and abrasion resistance, provided is a structural material containing iron and carbon, including: a first layer formed of pearlite; a second layer formed of a mixed phase of martensite and a carbide; and a third layer formed of a carbide, in order from a center to a surface of the structural material. The carbide of the third layer is represented by MC (where M is one element among Ti, V, Nb, Mo, Ta, and W), and the structural material has a concentration gradient in which an M element concentration is decreased from the surface to the center of the structural material.

1 . A structural material containing iron and carbon, comprising: a first layer formed of pearlite, a second layer formed of a mixed phase of martensite and a carbide, and a third layer formed of a carbide, in order from a center to a surface of the structural material, wherein
 the carbide of the third layer is represented by MC (wherein M is one element among Ti, V, Nb, Mo, Ta, and W), and   the structural material has a concentration gradient in which an M element concentration is decreased from the surface to the center.   
     
     
         2 . The structural material according to  claim 1 , wherein
 the carbide of the second layer is represented by M 3 C (wherein M is one element among Ti, V, Nb, Mo, Ta, and W), and   in the second layer, a spherical carbide is dispersed in the martensite to form the mixed phase.   
     
     
         3 . The structural material according to  claim 1 , wherein the third layer contains a carbonitride. 
     
     
         4 . The structural material according to  claim 1 , wherein the third layer has a Vickers hardness in a range of 1500 to 3500.