Martesitic stainless steel having excellent corrosion resistance

Abstract

The present invention provides a martesitic stainless steel having excellent corrosion resistance. The invention is characterized in that the martesitic stainless steel is composed of the following components: 0.03-0.25% by mass of C, 0.25-0.60% by mass of Si, less than 2.00% by mass of Mn, less than 0.035% by mass of P, less than 0.01% by mass of S, 11.0-15.5% by mass of Cr, less than 0.60% by mass of Ni, less than 0.80% by mass of Cu, 0.03-0.15% by mass of Sn, less than 0.10% by mass of V, less than 0.03% by mass of Al, 0.01-0.08% by mass of N, and the balance of Fe and inevitable impurities. Furthermore the ranges of Sn and N satisfy a formula (A), and furthermore the hardness is 300-600 HV through quenching or quenching tempering, wherein, Sn and N are percentages by mass. MCI=0.0016-(0.65Sn-0.059)<2>+(N-0.050)<2>>= 0 (A).

Description

technical field [0001] The present invention relates to a martensitic stainless steel excellent in corrosion resistance after quenching or quenching and tempering. More specifically, the present invention relates to a martensitic stainless steel which is used in the manufacture of western-style food knives, loom parts, tools, two-wheel disc brakes, etc., and which has excellent corrosion resistance even when it has a predetermined hardness. Background technique [0002] When simply characterizing the general-purpose steel grades (JIS standards) of martensitic stainless steels, SUS420J1 and SUS420J2 steels are generally used in tools such as Western-style food knives (table knives) or scissors, loom parts, and vernier calipers. SUS440A steel is used for high-hardness foreign-style kitchen knives and fruit knives. In addition, SUS410 steel is generally used in structural components such as two-wheel disc brakes or steel bars. The reason for this is that in such applications,...

AI Technical Summary

Problems solved by technology

In addition, since temper softening resistance increases, the heat treatment time required for tempering in the manufacturing process takes a long time, and there is a problem that productivity decreases.

[0009] In addition, the method described in Japanese Patent Laid-Open No. 2005-163176, that is, the technology of adding 0.06% to 0.10% of nitrogen in order to improve corrosion resistance without generating pinhole defects, is described in Japanese Patent Laid-Open No. 5-287456 In the same way, although the corrosion resistance is improved with the addition of nitrogen, since the amount of solid solution nitrogen seriously affects the quenching hardness, it is necessary to strictly control the amount of nitrogen, and there is a problem that manufacturing is troublesome.

In addition, the improvement of corrosion resistance by solid solution nitrogen is only 1.6% in terms of Cr content even if 0.1% of N is added, so it is not sufficient as a means for improving corrosion resistance.

[0010] Furthermore, in the method described in Japanese Patent Laid-Open No. 2005-248263, since the casting atmosphere is pressurized, in addition to requiring special equipment, there is also a problem that it is not suitable for mass production.

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