Steel sheet for textile machinery parts and method for manufacturing the same

Abstract

A steel sheet for textile machinery parts manufactured at a low cost and is excellent in wear resistance and toughness. The steel sheet for textile machinery parts contains, in mass %, 0.60% or more and 1.25% or less C, 0.50% or less Si, 0.30% or more and 1.20% or less Mn, 0.03% or less P, 0.03% or less S, 0.30% or more and 1.50% or less Cr, and 0.10% or more and 0.50% or less Nb, with the balance being Fe and unavoidable impurities. Furthermore, Nb-containing carbides having a particle size of 0.5 μm or more are present in the matrix at a density of 3000/mm 2 or more and 9000/mm 2 or less. Nb-containing carbides' effect of improving wear resistance can be ensured, and deterioration in toughness due to excessive formation of Nb-containing carbides can be prevented. Hence, the resulting wear resistance and toughness are good.

1 . A steel sheet for textile machinery parts, comprising in mass %, C: 0.60% or more and 1.25% or less, Si: 0.50% or less, Mn: 0.30% or more and 1.20% or less, P: 0.03% or less, S: 0.03% or less, Cr: 0.30% or more and 1.50% or less, and Nb: 0.10% or more and 0.50% or less, with the balance being Fe and unavoidable impurities,
 wherein Nb-containing carbides having a particle size of 0.5 μm or more are present in the matrix at a density of 3000/mm 2  or more and 9000/mm 2  or less.   
     
     
         2 . The steel sheet for textile machinery parts according to  claim 1 , comprising in mass %, Ti: 0% (no Ti added) or more and 0.50% or less, and B: 0% (no B added) or more and 0.005% or less. 
     
     
         3 . The steel sheet for textile machinery parts according to  claim 1 , comprising in mass %, any one or more types of Mo: 0% (no Mo added) or more and 0.50% or less, V: 0% (no V added) or more and 0.50% or less, and Ni: 0% (no Ni added) or more and 2.0% or less. 
     
     
         4 . A method for manufacturing a steel sheet for textile machinery parts, comprising performing slab heat treatment after casting, wherein:
 when a heating temperature is designated as “T” in the slab heat treatment, and Y=2.43−6000/(T+273) and X=0.68 (Nb content)+0.10 (C content)−10 Y  are employed, the heating temperature of the slab heat treatment is determined depending on the C content and the Nb content, so that a Z value represented by the formula, Z value=3.24exp (4.61X), is 6 or more and 20 or less; and,   upon casting, casting conditions are adjusted, so that the value of the average cooling rate during the cooling of the slab central part from the liquidus line temperature to the solidus line temperature is equal to or less than the Z value.   
     
     
         5 . The steel sheet for textile machinery parts according to  claim 2 , comprising in mass %, any one or more types of Mo: 0% (no Mo added) or more and 0.50% or less, V: 0% (no V added) or more and 0.50% or less, and Ni: 0% (no Ni added) or more and 2.0% or less.