NICKEL-CONTAINING STEEL FOR LOW TEMPERATURES AND TANK FOR LOW TEMPERATURES

摘要

A nickel-containing steel for low temperature service having a determined chemical composition of a Ni content of from 5.0 to 8.0%, in which the volume fraction of retained austenite in a region of 1.5 mm from a surface in the thickness direction is from 3.0 to 20.0% by volume, and the ratio of the hardness in a region of 1.0 mm from a surface in the thickness direction to the hardness in a region of 1/4 of the thickness from a surface in the thickness direction is 1.1 or less, and a low-temperature tank using the nickel-containing steel for low temperature service.