Patent ID: 6136109
Filing Date: 2000-10-24
Classification: C21D,C22C

Abstract:
A method of manufacturing a high-Cr martensite steel pipe having excellent pitting resistance and overall corrosion resistance, comprising:forming a pipe from a steel material comprising C: about 0.03 wt % or less, Si: about 0.5 wt % or less, Mn: about 0.5-3.0 wt %, Cr: about 10.0-14.0 wt %, Ni: about 0.2-2.0 wt %, Cu: about 0.2-0.7 wt %, N: about 0.03 wt % or less and the balance being Fe and incidental impurities, wherein a value X defined by the following formula (1):value X=(Cr%)+3(Cu%)-3(C%) (1)is about 12.2-14.2;austenitizing said pipe at a temperature substantially equal to the A.sub.C3 point or higher;quenching said pipe after austenitizing; andannealing said pipe in a temperature range from about 550.degree. C. to a temperature that is lower than the A.sub.C1 point of the steel.