Patent ID: 7785426

Claim:
A welded joint of a tempered martensitic heat resisting steel, wherein the heat resisting steel having a tempered martensite structure consists of the following elements by weight %, C: 0.03 to 0.15%, Si: 0.01 to 0.9%, Mn: 0.01 to 1.5%, Cr: 8.0 to 13.0%, Al: 0.0005 to 0.02%, Mo+W/2: 0.1 to 2.0%, V: 0.05 to 0.5%, N: 0.06% or less, Nb: 0.01 to 0.2%, B: 0.003 to 0.03%, Co: 0.1 to 5.0%, and the residue is composed of Fe and the following inevitable impurities by weight %, P: 0.03% or less, S: 0.01% or less, O: 0.02% or less, Mg: 0.01% or less, Ca: 0.01% or less, and Y and rare earth elements: a total amount of 0.01% or less, and wherein an area ratio of a microstructure depending on a microstructure of a base metal is 60% or more in a heat affected zone, and formation of fine prior austenite grains is suppressed in the heat affected zone.