Martensitic stainless steel wire rod and production method thereof

Abstract

The invention relates to a martensitic stainless steel wire rod and a production method thereof. The martensitic stainless steel wire rod is prepared from the following chemical components in weight percent: 0.30-0.65% of carbon, 0.20-0.50% of silicon, less than or equal to 0.60% of manganese, less than or equal to 0.30% of nickel, 11.50-17.00% of chromium, 0.20-0.50% of molybdenum, less than or equal to 0.25% of copper, less than or equal to 0.030% of sulfur, less than or equal to 0.040% of phosphorus, 0.02-0.20% of nitrogen, and the balance being ferrum and unavoidable impurities. The martensitic stainless steel wire rod which is excellent in surface, steady in performance and uniform in texture can be obtained by adopting the steps of smelting, casting, rolling, online hot charging annealing, salt bath, pickling, finishing to finished product inspecting and packaging, and the martensitic stainless steel wire rod has tensile strength of more than 600MPa, yield strength of more than 300MPa, elongation of more than 25%, percentage reduction of area of more than 50% and qualified product ratio of more than 85%. According to the invention, the comprehensive utilization performance of steel is improved, and the problem that surface stress cracking is easy to cause in annealing of high-carbon martensitic stainless steel in the prior art is solved on the basis of not increasing the smelting and rolling cost.

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...

AI Technical Summary

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 / T1220 is ≥735MPa, but the reduction of area is only ≥12%), which causes the high-strength (medium-high carbon) martensitic wire rod to fail due to low plasticity in the production process. It is very easy to crack, which reduces the yield of this type of stainless steel wire rod, so it needs to be softened annealed or spheroidized annealed, which increases energy consumption and also increases the manufacturing cost of this type of wire rod; 2) chrome-nickel stainless steel wire rod (Nickel-containing): 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 also 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

Images