摘要:
An object of this invention is to provide a high-strength steel endowed with high fatigue strength while also having increased strength and toughness, and a crankshaft manufactured using this high-strength steel. The high-strength steel according to the invention contains 0.30 mass % or more and 0.50 mass % or less of C, more than 0 mass % and 0.15 mass % or less of Si, 0.80 mass % or more and 1.5 mass % or less of Mn, 0.8 mass % or more and 2.4 mass % or less of Ni, 1.0 mass % or more and 3.0 mass % or less of Cr, 0.35 mass % or more and 0.70 mass % or less of Mo, 0.10 mass % or more and 0.25 mass % or less of V and 0.001 mass % or more and 0.040 mass % or less of Al, with the balance being iron and inevitable impurities. The high-strength steel is mainly composed of martensit, wherein a Mn concentration in cementite is 0.90 mass % or more and 1.80 mass % or less, and a ratio of Mn content to Si content is 5.50 or more.
摘要:
The present invention relates to a steel plate with excellent sour resistance, HAZ toughness and HAZ hardness, including, in terms of mass%, C: 0.02-0.20%, Si: 0.02-0.50%, Mn: 0.6-2.0%, P: over 0% and 0.030% or less, S: over 0% and 0.004% or less, Al: 0.010-0.08%, N: 0.001-0.01%, Nb: 0.002% or more and less than 0.05%, O: over 0% and 0.0040% or less, REM: 0.0002-0.05%, and Zr: 0.0003-0.020% with the remainder consisting of iron and inevitable impurities, in which an expression 10,000×[Nb]+31×Di-82‰¥0 (where Di = C / 10 0.5 × 1 + 0.7 × Si × 1 + 3.33 × Mn × ( 1 + 0.35 × Cu × 1 + 0.36 × Ni × 1 + 2.16 × Cr × 1 + 3 × Mo × 1 + 1.75 × V × 1.115 is satisfied, and, in the composition of inclusions with 1 µm or more width contained in steel, Zr amount is 1-40%, REM amount is 5-50%, Al amount is 3-30%, and S amount is over 0% and less than 20%.
摘要:
A thick steel plate for tanks which contains given components and satisfies the relationship (Ti content [Ti])×(N content [N])‰¥0.000085 and in which the nonmetallic particles having a size of 1 µm or larger in terms of equivalent circular diameter have a specific average composition and the Ti-containing nitrides satisfy specific average number densities.