CN112111637A

CN112111637A - Heat treatment method of stainless steel

Info

Publication number: CN112111637A
Application number: CN202011033136.4A
Authority: CN
Inventors: 邓吉宁
Original assignee: Jiangyou Changxiang Special Steel Manufacturing Co ltd
Current assignee: Jiangyou Changxiang Special Steel Manufacturing Co ltd
Priority date: 2020-09-27
Filing date: 2020-09-27
Publication date: 2020-12-22

Abstract

The invention provides a heat treatment method of stainless steel. The method solves the technical problems that the heat treatment method in the prior art sometimes easily causes the lack of necessary alloy elements at the grain boundary, causes the intergranular corrosion of the austenitic stainless steel in a corrosive medium, and influences the mechanical property of the austenitic stainless steel. The heat treatment method comprises the steps of carrying out solution treatment and sensitization treatment on the annealed steel billet. According to the heat treatment method of the stainless steel, the stainless steel material prepared by the heat treatment method can avoid the condition that necessary alloy elements are lacked at a crystal boundary, thereby avoiding intergranular corrosion of austenitic stainless steel in a corrosive medium and ensuring that the stainless steel material has good mechanical properties.

Description

Heat treatment method of stainless steel

Technical Field

The invention relates to smelting of stainless steel, in particular to a heat treatment method of stainless steel.

Background

The high-speed processing is one of five modern manufacturing technologies, and is an important component and development direction of the modern manufacturing technology. The high-speed tool system is one of important components required by a high-speed numerical control machine tool, is a connecting component of the machine tool and a cutter, and is a bridge for the cutter to play a cutting role. With the rapid development of science and technology, the military and civil requirements on the processing precision and the processing efficiency of the die and the workpiece are higher. The high-end lathe is the processing and manufacturing basis of a plurality of equipment and facilities, and the manufacturing technology of the hot-charging cutter handle material is widely applied to the fields of scientific research of major military affairs such as high-end weapon equipment, aerospace and the like and civil fields such as automobiles, household appliances, large molds and the like as a part of the high-end numerical control machine tool. The hot-assembled knife handle has extremely high requirements on indexes such as linear thermal expansion coefficient, tensile strength, durability, yield strength and the like of materials, the low-temperature hot assembly of the knife handle needs to be realized, and the requirement that the precision change does not exist even when the hot assembly and disassembly is carried out for more than 2000 times is met, so that a special heat treatment technology is needed to guarantee the product quality.

In modern industry, except for the requirement that steel materials can meet the strength requirement and precision requirement of use, the steel materials are mostly exposed to the external environment, so the corrosion resistance of mechanical parts is a design factor of key consideration, and austenitic stainless steel is widely applied. Although austenitic stainless steel has good corrosion resistance, the austenitic stainless steel is easy to cause the lack of necessary alloy elements at grain boundaries during heat treatment, so that the austenitic stainless steel is easy to generate intergranular corrosion in a corrosion medium. The austenitic stainless steel shows no sign of little damage on the outer surface due to intergranular corrosion, still has metallic luster, but loses good mechanical properties, is easy to cause intergranular fracture, and generates damage which is difficult to observe.

The applicant has found that the prior art has at least the following technical problems:

in the prior art, sometimes the heat treatment method easily causes that the grain boundary lacks necessary alloy elements, so that the austenitic stainless steel is easy to generate intergranular corrosion in a corrosive medium, and the mechanical property of the austenitic stainless steel is influenced.

Disclosure of Invention

The invention aims to provide a heat treatment method for stainless steel, which aims to solve the technical problems that the heat treatment method in the prior art is easy to cause the lack of necessary alloy elements at grain boundaries, so that the intergranular corrosion of austenitic stainless steel in a corrosive medium is easy to generate, and the mechanical property of the austenitic stainless steel is influenced. The technical effects produced by the preferred technical scheme in the technical schemes provided by the invention are explained in detail in the following.

In order to achieve the purpose, the invention provides the following technical scheme:

in the preparation of the stainless steel, after the annealing treatment of the steel billet, the solution treatment and the sensitization treatment are carried out on the annealed steel billet; wherein

The solution treatment is carried out by heating to 580-620 ℃ at a heating rate of 75-85 ℃/h and preserving the temperature for 110-130 min; heating to 990-1010 ℃ at a heating rate of 95-105 ℃/h, and preserving the heat at the temperature for 700-740 min; then quickly cooling to below 400 ℃;

the sensitization treatment is carried out by heating to 540-560 ℃ at a heating rate of 75-85 ℃/h and preserving the temperature for 850-950 min; then air-cooling to normal temperature to obtain the stainless steel finished product.

Further, the solution treatment is carried out by heating to 600 ℃ at a heating rate of 80 ℃/h, and keeping the temperature for 120 min; heating to 1000 ℃ at a heating rate of 100 ℃/h, and keeping the temperature for 720 min; then water cooling to below 400 ℃.

Further, the sensitization treatment is carried out by heating the mixture to 550 ℃ at a heating rate of 80 ℃/h, and the temperature is kept for 900 min; then air-cooling to normal temperature to obtain the stainless steel finished product.

Based on the technical scheme, the embodiment of the invention can at least produce the following technical effects:

according to the heat treatment method of the stainless steel, the stainless steel material prepared by the heat treatment method can avoid the condition that necessary alloy elements are lacked at a crystal boundary, further avoid intergranular corrosion of austenitic stainless steel in a corrosion medium, and ensure that the stainless steel material has good mechanical properties.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without making any creative effort, shall fall within the protection scope of the present invention.

Firstly, raw material description:

pure iron: pure iron produced by Changxiang special steel manufacturing company Limited in Jiangxiang oil city is adopted;

FeV 80: FeV80 produced by Panzhi vanadium company is adopted, which contains V80%;

a Cu plate: waste copper is adopted;

FeCr: FeCr55C25 produced by Guanghangshi power metallurgy burden company contains Cr 56%;

ni plate: the adopted Ni plate, 2# Ni, produced by Jinchuan group Limited company;

JMo: waste molybdenum is adopted;

al ingot: the Al ingot is pure aluminum produced by northwest aluminum processing branch company of aluminum industry limited company in China.

II, preparation example:

preparing stainless steel:

1. chemical composition and raw material

Stainless steel was prepared in examples 1 to 5, and the chemical composition (in mass%) thereof is shown in the following table 1, and the raw material ingredients (in parts by weight) thereof are shown in the following table 2:

TABLE 1 chemical composition of stainless steels in examples 1-5

	Example 1	Example 2	Example 3	Example 4	Example 5
						Carbon (%)	0.55	0.5	0.6	0.52	0.58
Silicon (%)	0.4	0.45	0.4	0.4	0.5
						Manganese (%)	7.6	8	7	7.2	7.8
Phosphorus (%)	0.015	0.016	0.013	0.016	0.015
						Sulfur (%)	0.003	0.005	0.004	0.003	0.003
Nickel (%)	7.7	7	8	7.8	7.4
						Chromium (%)	9.5	10	9	9.2	9.8
Molybdenum (%)	1.9	1.8	2	1.85	1.95
						Vanadium (%)	1.3	1.5	1	1.4	1.2
Copper (%)	2.4	2.3	2.5	.35	2.45
						Aluminum (%)	1.2	1.35	0.9	1.1	1.3
Iron (%)	Balance of	Balance of	Balance of	Balance of	Balance of

Table 2 raw material compounding tables for stainless steels in examples 1 to 5

	Example 1	Example 2	Example 3	Example 4	Example 5
						Pure iron	4282	4279	4273	4287	4290
FeV80	115	120	105	118	110
						Cu plate	172	170	181	170	175
FeCr	1204	1259	1148	1193	1225
						Ni plate	552	507	573	560	531
JMn	538	551	498	529	525
						JMo	135	120	140	120	130
Al ingot	100	105	109	95	108

2. Preparation method

Example 1:

the method comprises the following steps:

(1) preparing materials according to the mass percentage of the chemical components to obtain raw materials;

(2) induction vacuum degassing furnace smelting

B1, adding the raw materials prepared in the step (1) into an induction vacuum degassing furnace for melting, wherein the smelting melting rate of the induction vacuum degassing furnace is 40kg/min, and simultaneously adding lime and fluorite powder for slagging to avoid the exposure of molten steel;

b2, adding a diffusion deoxidizer while melting the raw materials; the diffusion deoxidizer is added after the molten pool can be seen, and 5kg of the deoxidizer is added every 30 min;

the diffusion deoxidizer is an Al-CaO agent; wherein the weight ratio of CaO to Al is 80: 20; the diffusion deoxidizer is added into the molten steel according to 6.6 kg/t;

b3, when the temperature in the smelting furnace rises to 1550 ℃, after the raw materials are fully melted into molten steel, sampling and fully analyzing, and preparing chemical components in the molten steel according to the chemical components in the stainless steel for the heat-shrinkable tool holder in the embodiment 1 in the table 1;

b4, when the result of the sampling total analysis reaches the chemical components in the stainless steel for the heat-shrinkable tool holder in the embodiment 1 in the table 1, slagging off;

b5, feeding an aluminum wire and a J-Ca wire for pre-deoxidation after slagging-off is finished;

the mass ratio of the fed aluminum wire to the molten steel is 0.9: 1000, parts by weight; the mass ratio of the fed J-Ca line to the molten steel is 0.1-0.115: 1000;

b6, after the feeding of the aluminum wire and the J-Ca wire is finished, closing the smelting furnace to carry out vacuum pumping, and carrying out vacuum treatment on the molten steel for 20min at the vacuum degree of less than or equal to 200Pa and the temperature of 1565 ℃;

b7, performing vacuum breaking treatment after the molten steel vacuum treatment is finished, and sampling and fully analyzing after the vacuum breaking treatment; verifying the accuracy of the adjustment of the chemical components in B3, and if the chemical components in the molten steel do not conform to the chemical components in the stainless steel for the heat-shrinkable tool holder of example 1 in Table 1, adjusting the chemical components again to conform to the chemical components in the stainless steel for the heat-shrinkable tool holder of example 1 in Table 1;

b8, final deoxidation: heating the molten steel to 1610 ℃, adding cerium into the molten steel, feeding J-Ca lines, adding nickel-magnesium alloy before tapping, and finally deoxidizing to ensure that the oxygen content is less than or equal to 30 ppm;

the cerium is added into the molten steel according to the proportion of 1 kg/t; the J-Ca line is added into the molten steel according to 0.105 kg/t; adding the nickel-magnesium alloy into the molten steel according to the proportion of 1 kg/t;

b9, tapping after final deoxidation, controlling the tapping temperature at 1610 ℃, and casting into an electrode rod by an ingot mold casting method after tapping to obtain a re-melted electrode rod for electroslag re-melting;

before casting, the tapped molten steel is firstly calmed, and the calm time is more than or equal to 5 min; before casting, argon is filled into the steel ingot mold, the pressure of the argon is 0.2Mpa, and the time is 2 min;

(3) electroslag remelting to obtain a steel ingot;

c1, preparing slag: the slag comprises the following components in parts by weight: 115 parts of binary premelting slag; 5 parts of magnesium oxide; 0.3 part of aluminum powder;

c2, heating the slag to a molten state, pouring the slag into a crystallizer, slowly inserting the remelted electrode rod obtained in the step (2) into the slag in the molten state, filling argon gas before arc striking, controlling the current to be 9000A, the voltage to be 41V and the time to be 60min during arc striking; electrifying to strike arc for remelting, controlling the current to be 10200A, the voltage to be 39V and the time to be 150min during remelting; filling after remelting, wherein the control current is 9000A, the voltage is 36V and the time is 30min during filling;

before inserting the remelting electrode rod into slag in a molten state, cutting a cap opening (the molten steel can shrink in a cooling process, and the cap opening refers to a concentrated shrinkage hole area arranged for preventing holes from being generated by shrinkage) of the remelting electrode, and then baking the remelting electrode rod at the temperature of more than 500 ℃ for 2 hours; argon is filled before the arc starts, the crystallizer is filled with argon for 5min, and the opening degree of the proportional valve is 30%; when the electroslag remelting obtains a steel ingot, arc striking is carried out through stainless steel turning scraps, a bottom pad sawed by the steel is used (the bottom pad is a piece with the thickness of 20-40mm after a cap opening is cut), and the bottom pad is baked for 2 hours at the temperature of more than or equal to 500 ℃;

c3, after the electroslag remelting filling, slowly cooling the steel ingot and then demoulding to obtain an electroslag remelting ingot;

the steel ingot slow cooling comprises the following steps: naturally cooling for 150min, then cover cooling for more than or equal to 24h, and finally air cooling to less than or equal to 50 ℃;

(4) forged steel billet

D1, flatting two ends of the electroslag remelting ingot obtained in the step (4), and cutting a bottom pad and a shrinkage cavity; heating at 850 deg.C for 1.5 hr or more, and heating at 1180 deg.C; upsetting and forging the electroslag remelting ingot, and slowly cooling the electroslag remelting ingot after forging to obtain a steel billet;

(5) annealing of steel billets

Annealing the steel billet subjected to slow cooling in the step (4), wherein flat ends at two ends of the annealing are subjected to rough machining and flaw detection, and then the steel billet is subjected to heat treatment;

(6) thermal treatment

F1 solution treatment

Heating to 600 ℃ at a heating rate of 80 ℃/h, and keeping the temperature for 120 min; heating to 1000 ℃ at a heating rate of 100 ℃/h, and keeping the temperature for 720 min; then cooling the water to below 400 ℃;

f2, sensitization treatment

After the solid solution treatment, heating to 550 ℃ at a heating rate of 80 ℃/h, and preserving the heat for 900min at the temperature; then air-cooling to normal temperature to obtain the stainless steel finished product.

Example 2:

in this example, the chemical components in the molten steel were prepared in accordance with the chemical components in the stainless steel of example 2 in table 1.

In this embodiment, the heat treatment method adopted is as follows:

f1 solution treatment

Heating to 580 deg.C at a heating rate of 75 deg.C/h, and maintaining the temperature at the temperature for 130 min; heating to 990 ℃ at a heating rate of 95 ℃/h, and keeping the temperature for 740 min; then cooling the water to below 400 ℃;

f2, sensitization treatment

After the solution treatment, the temperature is raised to 560 ℃ at the heating rate of 85 ℃/h, and the temperature is kept for 850 min; then air-cooling to normal temperature to obtain the stainless steel finished product.

The rest of the preparation steps are the same as example 1.

Example 3:

in this example, the chemical components in the molten steel were prepared in accordance with the chemical components in the stainless steel of example 3 in table 1.

In this embodiment, the heat treatment method adopted is as follows:

f1 solution treatment

Heating to 620 ℃ at a heating rate of 85 ℃/h, and keeping the temperature for 110 min; heating to 1010 ℃ at a heating rate of 105 ℃/h, and keeping the temperature for 700 min; then cooling the water to below 400 ℃;

f2, sensitization treatment

After the solid solution treatment, the temperature is raised to 540 ℃ at the heating rate of 75 ℃/h, and the temperature is kept for 950 min; then air-cooling to normal temperature to obtain the stainless steel finished product.

The rest of the preparation steps are the same as example 1.

Example 4:

in this example, the chemical components in the molten steel were prepared in accordance with the chemical components in the stainless steel of example 4 in table 1.

In this embodiment, the heat treatment method adopted is as follows:

f1 solution treatment

Heating to 590 ℃ at a heating rate of 78 ℃/h, and keeping the temperature for 125 min; heating to 995 ℃ at a heating rate of 98 ℃/h, and keeping the temperature for 730 min; then cooling the water to below 400 ℃;

f2, sensitization treatment

After the solution treatment, the temperature is increased to 545 ℃ at the heating rate of 78 ℃/h, and the temperature is kept for 930 min; then air-cooling to normal temperature to obtain the stainless steel finished product.

The rest of the preparation steps are the same as example 1.

Example 5:

in this example, the chemical components in the molten steel were prepared in accordance with the chemical components in the stainless steel of example 5 in Table 1.

In this embodiment, the heat treatment method adopted is as follows:

f1 solution treatment

Heating to 610 ℃ at a heating rate of 82 ℃/h, and keeping the temperature for 115 min; heating to 1005 ℃ at a heating rate of 102 ℃/h, and keeping the temperature for 710 min; then cooling the water to below 400 ℃;

f2, sensitization treatment

After the solution treatment, heating to 555 ℃ at the heating rate of 82 ℃/h, and preserving the heat for 870min at the temperature; then air-cooling to normal temperature to obtain the stainless steel finished product.

The rest of the preparation steps are the same as example 1.

Third, performance detection

1. The stainless steel materials prepared in examples 1 to 5 were subjected to the property test, and the test results are shown in the following table 3:

TABLE 3 Performance test results

2. According to the formula and the preparation method of the embodiment 1, smelting is carried out in different vacuum smelting furnaces at different times, and the performance parameters of the stainless steel for the heat-shrinkable tool shank prepared are shown in the following table 4:

TABLE 4 Performance test results

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention.

Claims

1. A heat treatment method of stainless steel is characterized in that: in the preparation of stainless steel, after annealing treatment of a steel billet, the annealed steel billet is subjected to solution treatment and sensitization treatment; wherein the content of the first and second substances,

the solution treatment is carried out by heating to 580-620 ℃ at a heating rate of 75-85 ℃/h and preserving the heat at the temperature for 110-130 min; heating to 990-1010 ℃ at a heating rate of 95-105 ℃/h, and preserving the heat at the temperature for 700-740 min; then quickly cooling to below 400 ℃;

the sensitization treatment is carried out by heating to 540-560 ℃ at a heating rate of 75-85 ℃/h and preserving heat at the temperature for 850-950 min; then air-cooling to normal temperature to obtain the stainless steel finished product.

2. A heat treatment method of stainless steel according to claim 1, characterized in that: the solution treatment is carried out by heating to 600 ℃ at a heating rate of 80 ℃/h and keeping the temperature for 120 min; heating to 1000 ℃ at a heating rate of 100 ℃/h, and keeping the temperature for 720 min; then water cooling to below 400 ℃.

3. A heat treatment method of stainless steel according to claim 2, characterized in that: the sensitization treatment is to heat up to 550 ℃ at a heating rate of 80 ℃/h and preserve heat at the temperature for 900 min; then air-cooling to normal temperature to obtain the stainless steel finished product.