CN102690940A

CN102690940A - Technological method for heat treatment of stainless steel bearing

Info

Publication number: CN102690940A
Application number: CN201110070273XA
Authority: CN
Inventors: 王衍涛; 范佳明; 马岩; 韩长涛
Original assignee: Wafangdian Metallurgy and Mining Bearing Manufacturing Co Ltd
Current assignee: Dalian Grandway Bearing Co., Ltd.
Priority date: 2011-03-23
Filing date: 2011-03-23
Publication date: 2012-09-26

Abstract

The invention provides a technological method for heat treatment of a stainless steel bearing. The method comprises: heating a workpiece in an annealing furnace to a temperature of 700-750DEG C, and conducting heat preservation for 4-4.5 hours, then first introducing the workpiece into a first heat treatment furnace, where heat preservation is performed at a temperature of 650-680DEG C for 30-40 minutes and then the temperature is raised to 850DEG C for 1 hour of heat preservation, and then after discharging, introducing the workpiece into the second heat treatment furnace, carrying out quenching treatment at a temperature of 1050-1060DEG C, and introducing nitrogen into the furnace for protection, implementing oil cooling on the treated workpiece to room temperature, then conducting subsection cooling, taking a mixture of alcohol and dry ice as a cooling liquid, controlling the temperature of the cooling liquid at minus 20-30DEG C and carrying out heat preservation for 30-25 minutes at the first phase, controlling the temperature of the cooling liquid at minus 65DEG C and carrying out heat preservation for 30-40 minutes at the second phase, and finally performing air cooled purging self-tempering treatment. The method of the invention solves the difficult problems of easy cracking, insufficient hardness and soft point generation in an oversize ultra-thick stainless steel bearing during heat treatment. The oversize bearing can have improved quenching hardness and hardness of uniformity, avoids cracking during heat treatment, and has good comprehensive mechanical properties.

Description

A kind of stainless steel bearing heat-treatment technology method

Technical field

The present invention relates to a kind of bearing heat-treatment technology method, particularly relate to a kind of heat-treatment technology method of super-huge stainless steel bearing.

Background technology

The stainless steel bearing conventional material is 9Cr18, is Martensite Stainless Steel, is applied in the specific bearing of working in the corrosive mediums such as seawater and oceanic climate usually; Because cause specifics such as material hardening capacity, conventional bearing is less usually, and net thickness is no more than 25mm; But along with mega-construction project machinery, particularly offshore operation large-scale fished for and the rise of special offshore work platform, and required stainless steel bearing develops to super-huge direction; After super-huge stainless steel bearing net thickness surpasses 40mm, surpassed the hardening capacity of material itself, the higher 1050-1060 of quenching temperature ℃ of employing simultaneously; Heat treatment stress is very big, simultaneously since deepfreeze to-65 ℃--70 ℃ stable, produce huge thermal treatment internal stress; Very easily produce hardening break; Because the back abundant residues austenite that quenches exists, and hardness and homogeneity can't satisfy request for utilization, product percent of pass is extremely low simultaneously.

Summary of the invention

The object of the invention; Provide a kind of stainless steel bearing heat-treatment technology method; This method is applicable to that bearing outside diameter surpasses 1200mm, and net thickness surpasses the especially big stainless steel bearing of 100mm, preferably resolves the difficult problem that heat treatment vessel is easy to crack, hardness is not enough and produce soft spots.

The technical scheme that adopts is:

A kind of stainless steel bearing heat-treatment technology method comprises following process step:

1, stress relief annealing: the stainless steel bearing workpiece (comprising bearing inner race, outer ring) that preliminary working goes out is put into lehre; After being heated to 700-750 ℃, lehre is incubated 4-4.5 hours; Be cooled to 400 ℃ of air coolings of coming out of the stove with stove; Thereby reach stress relief annealing, reduce the purpose of forging and machining stress;

2, divide stove segmentation preheating: adopt two heat treatment furnaces that the stainless steel bearing workpiece after handling through step 1 is carried out preheating; First heat treatment furnace is warming up to 800-850 ℃, second heat treatment furnace is warming up to 1000-1060 ℃, and first heat treatment furnace and second empty stove of heat treatment furnace are incubated 5-8 hours, make furnace temperature full and uniform;

To put into first heat treatment furnace through the stainless steel bearing workpiece after step 1 is handled; 650-680 ℃ of insulations 30-40 minutes; Be warming up to 850 ℃ again, be incubated 1-1.5 hours, get into immediately after coming out of the stove in second heat treatment furnace; The heating of under 1050-1060 ℃ of temperature, quenching, and in this stove, feed nitrogen protection; Stove segmentation preheating in this minute control temperature rise rate is heated evenly workpiece, reduces heat treatment stress;

3, powerful quench cooled: will carry out powerful quench cooled through the stainless steel bearing workpiece after the step 2 minute stove segmentation thermal pretreatment; Starting quenches stirs oily device and recycle pump; For improving the quench cooled effect, fuel-displaced after 20-30 minutes, carry out the segmentation processing under cooling after being cooled to room temperature;

4, segmentation processing under cooling: the deepfreeze medium adopts alcohol dry ice, and mixeding liquid temperature will be put into by alcohol and the dry and cold mixed solution of processing through the stainless steel bearing workpiece after step 3 is handled at subzero 20-30 ℃; And guarantee the complete submergence of above-mentioned workpiece; Be incubated 30-25 minutes, continue add dry ice and stir, when alcohol and dry ice mixed solution reach subzero 65 ℃; Stop to add dry ice, be incubated 30-40 minutes;

5, air-cooled purging self-tempering: adopt high wind cold to purging 5-10 minutes through the stainless steel bearing workpiece after the step 4 segmentation processing under cooling; Make this workpiece be warming up to-20 ℃ by-65 ℃ fast---directly send into tempering stove after-15 ℃ and carry out temper; The temper temperature is 155-160 ℃, and the temper time is 20-25 minutes, thoroughly eliminates quenching stress; Stabilizing tissue obtains good comprehensive mechanical property.

The difficult problem that the heat treatment vessel that the invention solves super-huge ultra thickness stainless steel bearing is easy to crack, hardness is not enough and produce soft spots.Improved the quenching hardness and the uniformity of hardness of extra large size bearing, avoided the thermal treatment cracking, the large-size stainless steel bearing enclose of handling through this heat-treatment technology method has good comprehensive mechanical performance.

Description of drawings

Fig. 1 is a thermal treatment process schema of the present invention.

Label among the figure:

(1) be stress relief annealing, for dividing stove segmentation preheating, (3) are the heating of quenching (2), and (4) are powerful quench cooled, and (5) are the segmentation deepfreeze, and rise again for air-cooled purging fast (6), and (7) are the tempering stabilizing treatment.

Embodiment

1, stress relief annealing: stainless steel bearing workpiece (inner ring, outer ring) is put into lehre, be heated to 720 ℃ after insulation 4 hours, be cooled to 400 air coolings of coming out of the stove with stove;

2, divide stove segmentation preheating:

Adopt two heat treatment furnaces, first heat treatment furnace is warming up to 800 ℃, and second heat treatment furnace is warming up to 1060 ℃, is incubated 5 hours, makes furnace temperature even.The stainless steel bearing workpiece is put into behind first heat treatment furnace 650 ℃ of insulations 30 minutes, risen to 850 ℃ of insulations 1 hour, get into immediately after coming out of the stove in second heat treatment furnace, get into the heating of quenching, guarantee to feed nitrogen protection in the stove.Quenching temperature is 1050-1060 ℃.

3, powerful quench cooled:

Oily device is stirred in quenching, and the recycle pump standard-sized sheet improves the quench cooled effect, and is fuel-displaced after 25-30 minutes, gets into the segmentation deepfreeze after being chilled to room temperature.

4, segmentation deepfreeze:

Alcohol dry ice is adopted in deepfreeze, and mixeding liquid temperature is in the time of subzero 20-30 ℃, and workpiece gets into, and guarantees complete submergence, is incubated 20 minutes continued and adds dry ice and stirring, stops to add dry ice at subzero 65 ℃, is incubated 30 minutes.

5, air-cooled purging self-tempering:

Workpiece purged 5 minutes after adopting air blast cooling to deepfreeze, was rapidly heated to-20 ℃--15 ℃ by-65 ℃ fast, and workpiece directly gets into tempering stove and carries out the tempering stabilizing treatment then, temper, and temperature is 155-160 ℃.Can thoroughly eliminate quenching stress, stabilizing tissue obtains good comprehensive mechanical performance.

Claims

1. stainless steel bearing heat-treatment technology method is characterized in that comprising following process step:

(1), stress relief annealing: the stainless steel bearing workpiece that preliminary working goes out is put into lehre, be incubated 4-4.5 hours after lehre is heated to 700-750 ℃, be cooled to 400 ℃ of air coolings of coming out of the stove with stove;

(2), divide stove segmentation preheating: adopt two heat treatment furnaces that the stainless steel bearing workpiece after handling through step (1) is carried out preheating; First heat treatment furnace is warming up to 800-850 ℃, second heat treatment furnace is warming up to 1000-1060 ℃, and first heat treatment furnace and second empty stove of heat treatment furnace are incubated 5-8 hours, make furnace temperature full and uniform;

To put into first heat treatment furnace through the stainless steel bearing workpiece after step (1) is handled; 650-680 ℃ of insulations 30-40 minutes; Be warming up to 850 ℃ again, be incubated 1-1.5 hours, get into immediately after coming out of the stove in second heat treatment furnace; The heating of under 1050-1060 ℃ of temperature, quenching, and in this stove, feed nitrogen protection;

(3), powerful quench cooled: will carry out powerful quench cooled through the stainless steel bearing workpiece after step (2) is divided stove segmentation thermal pretreatment, starting quenches stirs oily device and recycle pump, fuel-displaced after 20-30 minutes, carries out the segmentation processing under cooling again after being cooled to room temperature;

(4), segmentation processing under cooling: the deepfreeze medium adopts alcohol dry ice, and mixeding liquid temperature will be put into by alcohol and the dry and cold mixed solution of processing through the stainless steel bearing workpiece after step (3) is handled at subzero 20-30 ℃; And guarantee the complete submergence of above-mentioned workpiece; Be incubated 30-25 minutes, continuing adds dry ice and stirs, when alcohol and dry ice mixed solution reach subzero 65 ℃; Stop to add dry ice, be incubated 30-40 minutes;

(5), air-cooled purging self-tempering: employing high wind is cold to purge 5-10 minutes the stainless steel bearing workpiece after step (4) segmentation processing under cooling; Directly send into tempering stove after making this workpiece be warming up to-20 ℃--15 ℃ by-65 ℃ fast and carry out temper; The temper temperature is 155-160 ℃, and the temper time is 20-25 minutes.