摘要:
Age hardenable steel is low in hardness after hot forging, providing a machine part with the desired fatigue strength and yield strength by aging treatment, and high in toughness after aging treatment, comprising C: 0.09 to 0.20%, Si: 0.01 to 0.40%, Mn: 1.5 to 2.5%, S: 0.001 to 0.045%, Cr: over 1.00% to 2.00%, Al: 0.001 to 0.060%, V: 0.22 to 0.55%, N: over 0.0080 to 0.0170%, and a balance of Fe and impurities, where an area rate of bainite structures is 80% or more, an effective V ratio (amount of dissolved V/total amount of V) is 0.9 or more, a P and Ti in the impurities is P: 0.03% or less and Ti: less than 0.005%, and the chemical composition is one where the following F1 is 1.00 or less and the F2 is 0.30 or more: F 1 = C + 0.1 × Si + 0.2 × Mn + 0.15 × Cr + 0.35 × V F 2 = − 4.5 × C + Mn + Cr − 3.5 × V
摘要:
A non-thermal refined nitrocarburized component, including a steel material of a base metal, the steel material having a chemical composition consisting of: by mass%, C: 0.35 to 0.50%; Si: 0.10 to 0.35%; Mn: 2.3 to 2.8%; S: 0.01% or less; N: 0.0030 to 0.0250%; Cu: 0 to 1.0%; Mo: 0 to 0.3%; Ni: 0 to 0.5%; Ti: 0 to 0.020%, and the balance: Fe and impurities, wherein 3.10≤(0.316C+0.122)×(0.7Si+1)×(5.1Mn-1.12)×(0.364Ni+1)×(2.16Cr+1)×(3Mo+1)≤6.00, and the impurities include P: 0.08% or less, Al: 0.05% or less, and Cr: less than 0.20%, and wherein at a stress concentrated region, an HV hardness at a position of 0.05 mm from a surface is 410 to 480, an HV hardness at a position of 1.0 mm from the surface is 200 or more, a compound-layer depth is 5µm or less, and a metal micro-structure of the base metal is a bainite micro-structure. The non-thermal refined nitrocarburized component has an excellent bending straightening property and a high fatigue strength.
摘要:
Age hardening steel excellent in machinability before aging treatment and excellent in fatigue characteristics, toughness, and low cycle fatigue characteristics after aging treatment, that is, age hardening steel containing predetermined amounts of C, Si, Mn, S, Cr, Al, V, Nb, Ca, and REM, limiting contents of P, Ti, and N to predetermined amounts or less, having a balance of Fe and impurities, having an area ratio of bainite structures of 70% or more, and, furthermore, having a chemical composition where F1 expressed by C+0.3×Mn+0.25×Cr is 0.68 or more, F2 expressed by C+0.1×Si+0.2×Mn+0.15×Cr+0.35×V is 0.85 or less, F3 expressed by -4.5×C+Mn+Cr-3.5×V is 0.00 or more, and F4 expressed by 10×Ca+REM is 0.012 to 0.08, is provided. Note that, the symbols of elements in the formulas showing F1 to F4 mean the contents by mass% of those elements.