Powder lubricant composition and method for manufacturing seamless steel pipe

1. A method for manufacturing a seamless steel pipe, comprising:

adhering a powder lubricant composition to a pipe inner surface of a work piece which is piercing rolled to have a tubular shape; and

elongation rolling on the work piece after the adhering of the powder lubricant composition,

wherein the powder lubricant composition comprises:

sodium borate: 65 parts by mass to 95 parts by mass;

cryolite: 5 parts by mass to 35 parts by mass; and

at least one selected from the group consisting of a fatty acid sodium salt and a fatty acid calcium salt: 0 parts by mass to 25 parts by mass,

wherein a total of sodium borate and cryolite is 100 parts by mass,

and wherein a temperature of the work piece before initial rolling in the elongation rolling is 700° C. or higher and lower than 820° C.

2. The method for manufacturing a seamless steel pipe according to claim 1 , wherein

a total reduction in the elongation rolling is 50% to 80%.

3. The method for manufacturing a seamless steel pipe according to claim 2 , wherein

the elongation rolling is performed by a mandrel mill rolling.

4. The method for manufacturing a seamless steel pipe according to claim 1 , wherein

the elongation rolling is performed by a mandrel mill rolling.

5. The method for manufacturing a seamless steel pipe according to claim 1 , wherein a concentration of the sodium borate in the powder lubricant composition is 70 parts by mass to 95 parts by mass, and a concentration of the cryolite in the powder lubricant composition is 5 parts by mass to 30 parts by mass.

6. The method for manufacturing a seamless steel pipe according to claim 1 , wherein a concentration of the sodium borate in the powder lubricant composition is 70 parts by muss to 90 parts by mass, and a concentration of the cryolite in the powder lubricant composition is 10 parts by mass to 30 parts by mass.

7. The method for manufacturing a seamless steel pipe according to claim 1 , wherein a concentration of the sodium borate in the powder lubricant composition is 70 parts by mass to 80 parts by mass, and a concentration of the cryolite in the powder lubricant composition is 20 parts by mass to 30 parts by mass.

8. The method for manufacturing a seamless steel pipe according to claim 1 , wherein

the total of sodium borate and cryolite is 80 mass % to 100 mass % of the powder lubricant composition.

9. The method for manufacturing a seamless steel pipe according to claim 1 , wherein a concentration of the sodium borate in the powder lubricant composition is 65 parts by mass to 95 parts by mass, a concentration of the cryolite in the powder lubricant composition is 5 parts by mass to 35 parts by mass, and a concentration of the at least one selected from the group consisting of a fatty acid sodium salt and a fatty acid calcium salt is 5 parts by mass to 25 parts by mass.

10. The method for manufacturing a seamless steel pipe according to claim 1 , wherein

the elongation rolling starts when the work piece has a temperature of 700° C. or higher and lower than 820° C.