Welded joint of tempered martensite based heat-resistant steel
View Patent ↗A welded joint of a tempered martensitic heat resisting steel includes a fine-grained heat affected zone of weldment of a heat resisting steel having a tempered martensite structure which exhibits a creep strength of 90% or more of the creep strength of the base metal thereof. The welded joint is inhibited in the formation of the fine-grained HAZ exhibiting a significantly reduced creep strength.
1. 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.
2. 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%,
Ni: 0.5% or less,
Cu: 1.7% or less, 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.