A kind of martensitic stainless steel wire rod and its manufacturing method

Abstract

A martensitic stainless steel wire rod and its manufacturing method, the chemical composition weight percentage of the martensitic stainless steel wire rod is: carbon 0.30-0.65%, silicon 0.20-0.50%, manganese≤0.60%, nickel≤0.30%, chromium 11.50-17.00%, molybdenum 0.20-0.50%, copper ≤0.25%, sulfur ≤0.030%, phosphorus ≤0.040%, nitrogen 0.02-0.20%, and the rest are iron and unavoidable impurities. Using smelting, casting, rolling, on-line hot charging and annealing, after salt bath, pickling, finishing, inspection and packaging of finished products, martensitic stainless steel wire rods with excellent surface, stable performance and uniform structure are obtained. The tensile strength > 600MPa, yield strength > 300Mpa, elongation > 25%, reduction of area > 50%, yield > 85%. The invention improves the comprehensive performance of the steel, and solves the problem that surface stress cracks easily occur during the annealing of the existing medium-high carbon martensitic stainless steel without increasing smelting and rolling costs.

Description

technical field [0001] The invention relates to a martensitic stainless steel wire rod and a manufacturing method thereof. Background technique [0002] Martensitic stainless steel is a class of stainless steel whose properties can be adjusted by heat treatment (quenching, tempering). This type of steel must meet two basic conditions: First, there must be an austenite phase region in the equilibrium phase diagram, and it must be heated for a long time within the temperature range of this region to make the carbide dissolve into the steel, and then quench to form Martensite, that is, the chemical composition must be controlled in the γ or γ+α phase region. Second, to make the alloy form a corrosion-resistant and oxidation-resistant passivation film, the chromium content must be above 10.5%. According to the difference of alloying elements, it can be divided into martensitic chromium stainless steel and martensitic chromium-nickel stainless steel. [0003] Wire rod is also c...

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Problems solved by technology

[0004] At present, martensitic stainless steel wire rods are mainly divided into two categories: 1) Chromium stainless steel wire rods (nickel-free): typical steel types are 12Cr12, 06Cr13, 12Cr13, Y12Cr13, 20Cr13, 30Cr13, 40Cr13, 68Cr17, 85Cr17, 95Cr18, The manufacturing cost of this type of material is low (excluding Ni), the strength after quenching and tempering is 490-735MPa, and the reduction of area is 8-25% (GB / T1220); however, with the increase of strength, this type of stainless steel wire rod The plasticity of the wire rod is obviously reduced (for example, the strength of 30Cr13 in GB / T 1220 is ≥735MPa, but the reduction of area is only ≥12%), which causes high-strength (medium-high carbon) martensitic wire rods in the production process due to low plasticity And it is very easy to crack, which reduces the yield of this type of stainless steel wire rod, so it is necessary to carry out softening annealing or spheroidizing annealing to it, which increases energy consumption and also increases the manufacturing cost of this type of wire rod; 2) chrome-nickel stainless steel plate Bar (containing nickel): typical steel types are 2Cr17Ni3, X3CrNiMo13-4, X4CrNiMo16-5-1, the strength after quenching and tempering is high, 760-1100MPa, which can meet the strength requirements of stainless steel parts and components, and the plasticity is relatively high. Good (the reduction of area of ​​2Cr17Ni3 is 17-25%; the reduction of area of ​​X3CrNiMo13-4 is 15-20%; the reduction of area of ​​X4CrNiMo16-5-1 is 20-25%), and it is not easy to crack during the production process

However, the Ni content in steel is as high as 3.0-6.0%, because Ni is a precious metal element, which greatly increases the cost of steel and inhibits the popularization and application of this type of material

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