Martensitic stainless steel for building structure fastener and manufacturing method thereof

Abstract

The invention discloses martensitic stainless steel for a building structure fastener and a manufacturing method thereof. The martensitic stainless steel comprises the following chemical components in percentage by weight: 0.10-0.20% of C, 0.05-0.15% of N, Si not more than 1%, Mn not more than 1%, P not more than 0.035%, S not more than 0.010%, 13.0-14.0% of Cr, 1.5-2.5% of Mo, 0.3-0.8% of Cu, 1.5-2.5% of Ni, and the balance of Fe and inevitable impurities; and the following conditions can be synchronously satisfied: the pitting equivalent weight PRE is more than 20%; and PRE=Cr+3.3 Mo+16 N. The prepared martensitic stainless steel has the pitting potential more than 270 mV, has the Rockwell hardness number of 52-54 HRC, has equivalent corrosion resistance to 304 stainless steel, and has high strength, high hardness and excellent hot working performance and cold forming performance.

Description

technical field [0001] The invention relates to martensitic stainless steel, in particular to a martensitic stainless steel used for building structure fasteners and a manufacturing method thereof, in particular to a martensitic stainless steel used for fasteners with good corrosion resistance, hot workability and cold formability Tensitic stainless steel and its manufacturing method. Background technique [0002] When the roof or wall material is aluminum alloy or stainless steel, the fastener material must be stainless steel. In order to maximize the service life of the building envelope system, the service life of stainless steel fasteners should match the envelope system. This means that the corrosion resistance of the fasteners should match the material of the enclosure system. When the enclosure system uses austenitic stainless steel 304, 316 or aluminum alloy, the corrosion resistance of the fasteners should be at least as good as that of austenitic stainless steel. ...

AI Technical Summary

Problems solved by technology

However, the disadvantage of this screw is that due to the potential difference between the materials on both sides of the welding part of austenitic stainless steel 304 and martensitic stainless steel 410S, galvanic corrosion is prone to occur, and the martensitic stainless steel 410S in the tapping part has high strength and poor corrosion resistance. Easy to fracture and fail at the place where pitting corrosion occurs

[0008] Based on the problem of poor corrosion resistance of conventional martensitic stainless steel, technical personnel have conducted research, but there are still only a few martensitic stainless steels whose corrosion resistance reaches the level of 250-300mV of austenitic stainless steel 304

Chinese patent CN104278199 improves corrosion resistance by adding Mo, Cu and N, and the pitting potential can reach 270-300mV, reaching the level of austenitic stainless steel 304, but the carbon content of this steel is very high, 0.28-0.35%. The formability is poor, and because it contains 2.5-3.5% Cu, the low melting point Cu-rich phase on the surface is very easy to cause surface defects during hot rolling

[0009] Similarly, the Chinese patent CN101233254A adopts an approximate alloy design, which also has the problems of high carbon content and high copper content. Even if Ni is added, it is difficult to avoid the problem of surface defects in hot working due to the low Ni content.

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