HIGH TENSILE STRENGTH STEEL HAVING FAVORABLE DELAYED FRACTURE RESISTANCE AND METHOD FOR MANUFACTURING THE SAME
First Claim
Patent Images
1. A high tensile strength steel comprising elements C:
- 0.02 to 0.25%, Si;
0.01 to 0.8%, Mn;
0.5 to 2.0%, Al;
0.005 to 0.1%, N;
0.0005 to 0.008%, P;
0.02% or lower, and S;
0.004% or lower, all in percent by mass, and Fe and an unavoidable impurity as a balance, wherein an average aspect ratio of a prior austenite grain calculated over entire thickness is at least three.
1 Assignment
0 Petitions
Accused Products
Abstract
High tensile strength steels that have both favorable delayed fracture resistance and a tensile strength of 600 MPa or higher and are suitably used in construction machinery, tanks, penstocks, and pipelines, as well as methods for manufacturing such steels are provided. The safety index of delayed fracture resistance (%) is 100×(X1/X0), where X0: reduction of area of a specimen substantially free from diffusible hydrogen, and X1: reduction of area of a specimen containing diffusible hydrogen.
4 Citations
20 Claims
-
1. A high tensile strength steel comprising elements C:
- 0.02 to 0.25%, Si;
0.01 to 0.8%, Mn;
0.5 to 2.0%, Al;
0.005 to 0.1%, N;
0.0005 to 0.008%, P;
0.02% or lower, and S;
0.004% or lower, all in percent by mass, and Fe and an unavoidable impurity as a balance, wherein an average aspect ratio of a prior austenite grain calculated over entire thickness is at least three. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- 0.02 to 0.25%, Si;
-
10. A high tensile strength steel comprising elements C:
- 0.02 to 0.25%, Si;
0.01 to 0.8%, Mn;
0.5 to 2.0%, Al;
0.005 to 0.1%, N;
0.0005 to 0.008%, P;
0.02% or lower, and S;
0.004% or lower, all in percent by mass, and Fe and an unavoidable impurity as a balance, wherein an average aspect ratio of a prior austenite grain calculated over entire thickness is at least three. - View Dependent Claims (11, 12, 13, 14)
- 0.02 to 0.25%, Si;
-
15. A high tensile strength steel comprising elements C:
- 0.02 to 0.25%, Si;
0.01 to 0.8%, Mn;
0.5 to 2.0%, Al;
0.005 to 0.1%, N;
0.0005 to 0.008%, P;
0.02% or lower, and S;
0.003% or lower, all in percent by mass, and Fe and an unavoidable impurity as a balance, wherein an average aspect ratio of a prior austenite grain calculated over entire thickness is at least three and a cementite covering ratio measured at a boundary of a lath is 50% or lower. - View Dependent Claims (16, 17, 18, 19, 20)
- 0.02 to 0.25%, Si;
Specification