阅读说明：本技术 15-5ph稀土马氏体不锈钢的制造方法 (Method for manufacturing 15-5PH rare earth martensitic stainless steel ) 是由 陈坚 陈菊生 向彪 于 2020-04-30 设计创作，主要内容包括：本发明公开了一种15-5PH稀土马氏体不锈钢的制造方法,包括钢材的酸洗、钢材的冶炼制造、钢材的锻造、钢材的热处理,所述钢材的冶炼制造过程为：选用微碳铬铁、0＃镍板、电解铜以及原生态废钢中的一种或多种组合作为原材料,对原材料进行酸洗,依次进行EF熔炼、VOD真空精炼以及ESR电渣重熔,得到钢锭。本发明的优点是：由于在EF熔炼过程中加入复合脱氧剂SiMnAlCa,经化合反应,与钢水中氧化物、硫化物形成钢渣,经过三次扒渣,可以减少非金属夹杂物,并且在熔炼后期出钢前加入占钢水的质量比为0.2-0.3‰的微量CeNd混合稀土,可有效改善低温韧性,获得高强度、低温冲击韧性好的15-5PH稀土马氏体不锈钢。(The invention discloses a manufacturing method of a 15-5PH rare earth martensitic stainless steel, which comprises the steps of acid pickling of steel, smelting and manufacturing of the steel, forging of the steel and heat treatment of the steel, wherein the smelting and manufacturing process of the steel comprises the following steps: selecting one or more of micro-carbon ferrochrome, 0 # nickel plate, electrolytic copper and original ecological steel scrap as raw materials, pickling the raw materials, and sequentially carrying out EF smelting, VOD vacuum refining and ESR electroslag remelting to obtain the steel ingot. The invention has the advantages that: because the composite deoxidizer SiMnAlCa is added in the EF smelting process, the deoxidizer SiMnAlCa forms steel slag with oxides and sulfides in molten steel through chemical combination reaction, non-metallic inclusions can be reduced through three-time slag skimming, and trace CeNd mixed rare earth accounting for 0.2-0.3 per mill of the mass ratio of the molten steel is added before tapping in the later smelting period, the low-temperature toughness can be effectively improved, and the 15-5PH rare earth martensitic stainless steel with high strength and good low-temperature impact toughness can be obtained.)

1. A manufacturing method of 15-5PH rare earth martensitic stainless steel is characterized in that the manufacturing method selects one or a combination of more of micro-carbon ferrochrome, 0 # nickel plate, electrolytic copper and original ecological scrap steel as raw materials to be smelted, CeNd mischmetal is added before tapping, and the mass ratio of the CeNd mischmetal to molten steel is 0.2-0.3 per mill; obtaining the 15-5PH rare earth martensitic stainless steel, wherein the 15-5PH rare earth martensitic stainless steel comprises the following components in parts by weight: less than or equal to 0.07 percent of C, less than or equal to 1.00 percent of Si, less than or equal to 1.00 percent of Mn, 14.00 to 15.00 percent of Cr14, 50 to 5.50 percent of Ni, less than or equal to 0.03 percent of P, less than or equal to 0.015 percent of S, 2.50 to 4.50 percent of Cu, 0.15 to 0.45 percent of Nb and Ta, less than or equal to 0.50 percent of Mo, and the balance of Fe.

2. A method of manufacturing a 15-5PH rare earth martensitic stainless steel as claimed in claim 1 wherein said method of manufacturing comprises the steps of:

(1) selecting one or more of micro-carbon ferrochrome, 0 # nickel plate, electrolytic copper and original ecological steel scrap as raw materials;

(2) acid washing the raw materials by using dilute sulfuric acid, washing acid stains by using clear water, and drying the acid stains to enter a furnace;

(3) cleaning a hearth and a steel ladle of the steel furnace, wherein the cleaning method is to smelt 1-2 furnaces of 17-4PH steel;

(4) smelting the raw materials in the step (2) in a smelting mode that: sequentially carrying out EF electric arc furnace smelting, VOD vacuum refining and ESR electroslag remelting to obtain a steel ingot; adding a composite deoxidizer SiMnAlCa in the smelting process of the EF electric arc furnace to enable oxide and sulfide in molten steel to form compound slag to float on the surface of the molten steel, and removing the compound slag three times before oxidation period later stage, reduction period and tapping so as to reduce non-metallic inclusions in the molten steel; adding the CeNd misch metal before tapping at the later smelting stage of the EF electric arc furnace, wherein the mass ratio of the CeNd misch metal to the molten steel is 0.2-0.3 per mill, and tapping after stirring for 5-10 minutes;

(5) carrying out forced pressing and quick forging on the steel ingot by adopting a large press and applying an FM (frequency modulation) method, wherein the forging ratio is more than or equal to 3, and carrying out hydrogen diffusion annealing after forging to obtain a forged piece;

(6) and sequentially carrying out solution heat treatment at 1040 +/-10 ℃, quenching and tempering at 760 +/-10 ℃ and aging treatment at 480 +/-10 ℃ on the forged piece to obtain the 15-5PH rare earth martensitic stainless steel.

3. A method of making a 15-5PH rare earth martensitic stainless steel as claimed in claim 2 wherein the dilute sulphuric acid has a solute mass fraction of 5%.

4. The method for manufacturing the 15-5PH rare earth martensitic stainless steel as claimed in claim 2 wherein the composite deoxidizer SiMnAlCa comprises the following components by mass: 7-8% of Si, 18-19% of Mn, 5-5.5% of Al, 4-4.5% of Ca and the balance of Fe.

5. The method as claimed in claim 2, wherein the smelting process adopts a stepped fractional heating method: heating to 50 ℃ per hour at the temperature of between 20 and 560 ℃, and keeping the temperature for 1 to 2 hours; heating to 80 ℃ per hour between 560 ℃ and 860 ℃, and keeping the temperature for 1 to 2 hours; heating to 860-1200 deg.c at 100 deg.c per hour and maintaining for 2-3 hr.

6. The method for manufacturing a 15-5PH rare earth martensitic stainless steel as claimed in claim 1 wherein the 15-5PH rare earth martensitic stainless steel comprises the following components by mass: 0.06% of C, 0.47% of Si, 0.56% of Mn, 14.10% of Cr, 4.50% of Ni4, 0.015% of P, 0.009% of S, 3.60% of Cu, 0.35% of Nb + Ta, 0.43% of Mo and the balance of Fe.

Technical Field

The invention relates to the field of metallurgy, in particular to a method for manufacturing a 15-5PH rare earth martensitic stainless steel.

Background

The 15-5PH rare earth martensitic stainless steel is steel for polar environment and special ships; the yield strength is more than or equal to 1000MPa, the tensile strength is more than or equal to 1050MPa, the elongation is more than or equal to 14 percent, the impact toughness at minus 20 ℃ is more than or equal to 150J, the impact toughness at minus 84 ℃ is more than or equal to 80J, the CTOD at minus 20 ℃ is more than or equal to 0.2mm, the A, B types are less than or equal to 1 grade, and the C, D types are less than or equal to 0.5 grade. No corresponding steel grade can be found in China, and the pH value of 15-5 in the United states is similar, but the low-temperature impact and the non-metallic inclusions are not checked.

Disclosure of Invention

The invention aims to provide a method for manufacturing 15-5PH rare earth martensitic stainless steel according to the defects of the prior art, which mainly comprises the steps of acid pickling of steel, smelting and manufacturing of the steel, forging of the steel and heat treatment of the steel, wherein a composite deoxidizer SiMnAlCa is added in the EF smelting process to effectively reduce nonmetallic inclusions, and trace CeNd mixed rare earth is added before tapping to obtain the 15-5PH rare earth martensitic stainless steel with high strength and good low-temperature impact property.

The purpose of the invention is realized by the following technical scheme:

a manufacturing method of 15-5PH rare earth martensitic stainless steel is characterized in that the manufacturing method selects one or a combination of more of micro-carbon ferrochrome, 0 # nickel plate, electrolytic copper and original ecological scrap steel as raw materials to be smelted, CeNd mischmetal is added before tapping, and the mass ratio of the CeNd mischmetal to molten steel is 0.2-0.3 per mill; obtaining the 15-5PH rare earth martensitic stainless steel, wherein the 15-5PH rare earth martensitic stainless steel comprises the following components in parts by weight: less than or equal to 0.07 percent of C, less than or equal to 1.00 percent of Si, less than or equal to 1.00 percent of Mn, 14.00 to 15.00 percent of Cr14, 50 to 5.50 percent of Ni, less than or equal to 0.03 percent of P, less than or equal to 0.015 percent of S, 2.50 to 4.50 percent of Cu, 0.15 to 0.45 percent of Nb and Ta, less than or equal to 0.50 percent of Mo, and the balance of Fe.

The manufacturing method comprises the following steps:

(1) selecting one or more of micro-carbon ferrochrome, 0 # nickel plate, electrolytic copper and original ecological steel scrap as raw materials;

(2) acid washing the raw materials by using dilute sulfuric acid, washing acid stains by using clear water, and drying the acid stains to enter a furnace;

(3) cleaning a hearth and a steel ladle of the steel furnace, wherein the cleaning method is to smelt 1-2 furnaces of 17-4PH steel;

(4) smelting the raw materials in the step (2) in a smelting mode that: sequentially carrying out EF electric arc furnace smelting, VOD vacuum refining and ESR electroslag remelting to obtain a steel ingot; adding a composite deoxidizer SiMnAlCa in the smelting process of the EF electric arc furnace to enable oxide and sulfide in molten steel to form compound slag to float on the surface of the molten steel, and removing the compound slag three times before oxidation period later stage, reduction period and tapping so as to reduce non-metallic inclusions in the molten steel; adding the CeNd misch metal before tapping at the later smelting stage of the EF electric arc furnace, wherein the mass ratio of the CeNd misch metal to the molten steel is 0.2-0.3 per mill, and tapping after stirring for 5-10 minutes;

(5) carrying out forced pressing and quick forging on the steel ingot by adopting a large press and applying an FM (frequency modulation) method, wherein the forging ratio is more than or equal to 3, and carrying out hydrogen diffusion annealing after forging to obtain a forged piece;

(6) and sequentially carrying out solution heat treatment at 1040 +/-10 ℃, quenching and tempering at 760 +/-10 ℃ and aging treatment at 480 +/-10 ℃ on the forged piece to obtain the 15-5PH rare earth martensitic stainless steel.

The solute mass fraction of the dilute sulfuric acid is 5%.

The composite deoxidizer SiMnAlCa comprises the following components in parts by mass: 7-8% of Si, 18-19% of Mn, 5-5.5% of Al, 4-4.5% of Ca and the balance of Fe.

The smelting process adopts a step type fractional heating method: heating to 50 ℃ per hour at the temperature of between 20 and 560 ℃, and keeping the temperature for 1 to 2 hours; heating to 80 ℃ per hour between 560 ℃ and 860 ℃, and keeping the temperature for 1 to 2 hours; heating to 860-1200 deg.c at 100 deg.c per hour and maintaining for 2-3 hr.

The 15-5PH rare earth martensitic stainless steel comprises the following components in parts by weight: 0.06% of C, 0.47% of Si, 0.56% of Mn, 14.10% of Cr14, 4.50% of Ni, 0.015% of P, 0.009% of S, 3.60% of Cu, 0.35% of Nb + Ta, 0.43% of Mo and the balance of Fe.

The invention has the advantages that: adding a composite deoxidizer SiMnAlCa in the EF smelting process, enabling the composite deoxidizer to form steel slag through a chemical combination reaction and oxide sulfide in steel, and removing slag for three times to purify molten steel, thereby effectively reducing nonmetallic inclusions; the CeNd mixed rare earth accounting for 0.2-0.3 per mill of the mass ratio of the molten steel is added before tapping, so that the low-temperature toughness can be effectively improved, and the performances of the rare earth martensitic stainless steel with the pH of 15-5 can reach the standard of steel for polar environment, thereby meeting the design requirements.

Detailed Description

The features of the present invention and other related features are described in further detail below by way of examples to facilitate understanding by those skilled in the art: