CN105755266A - Gear quenching technology - Google Patents

Abstract

The invention discloses a gear quenching technology. The technology includes: quenching temperature, which is set at 800DEG C; quenching time, which is calculated by an empirical formula and finally determined by experiments, with the common empirical formula being t=a*k*D, wherein T refers to heating time (min or s), a refers to a heating coefficient (min/mm or s/mm), D refers to effective thickness (mm) of the workpiece, and k refers to workpiece charging condition correction coefficient, usually 1.0-1.5; quenching heating speed: for large castings and forgings having complex shape and small distortion requirement or being manufactured from alloy steel, generally the temperature is raised to 600-700DEG C at a speed of 30-70DEG C/h, after a period of temperature equilibrium, the temperature is raised at a speed of 50-100DEG C/h, and medium and low carbon steel with a simple shape, and medium carbon alloy constructional steel with a diameter of less than 400mm can be directly heated in a warming furnace; and quenching cooling medium: the cooling speed has to be greater than the critical cooling speed of steel so as to convert the high temperature phase austenite in steel into low temperature metastable phase martensite in the cooling process.

Description

A kind of gear quenching technique

Technical field

The present invention relates to a kind of gear quenching technique.

Background technology

The adjustment in processing step and device parameter etc. of the existing gear quenching technique there is also certain empirical and technical, for the operator newly started with, in addition it is also necessary to carry out substantial amounts of exercise and could grasp operation skill, produces the good product of quality.

Summary of the invention

In order to realize the purpose of the present invention, the present invention provides the gear quenching technique of a kind of easy to operate, quick, easy left-hand seat.

For solving above-mentioned technical problem, the present invention adopts the following technical scheme that

A kind of gear quenching technique, including following operation:

1), quenching temperature

The quenching of steel is that steel is heated to critical temperature Ac3(sub-eutectoid steel) or Ac1(hypereutectoid steel) more than a certain temperature, insulation a period of time, so as to all or part of austenite 1 is changed, then carry out the Technology for Heating Processing that martensite (or bainite) changes being as cold as below Ms (or isothermal near Ms) soon more than the cooling rate of critical cooling rate；

Quenching temperature is set as 800 DEG C at this by the transformation temperature of steel；

2), the Quench heating time

Quenching Soaking Time is determined by many factors such as equipment mode of heating, accessory size, the composition of steel, batch and plant capacities；The Quench heating time should include the whole cross section of workpiece and be heated to predetermined hardening heat, and so as to complete the time needed for structural transformation, carbide dissolution and homogeneity of austenite component at such a temperature, therefore, the Quench heating time includes heating up and two periods of insulation；In actual production, only in large-scale workpiece or a lot of situation of batch, just heating-up time and temperature retention time are accounted for respectively, generally heating-up time and temperature retention time are referred to as the Quench heating time；Under concrete working condition, the Quench heating time, conventional empirical equation calculated, and finally determined by experiment, and conventional empirical equation is:

t=a×k×D

In formula, T heat time heating time (min or s), a heating coefficient (min/mm or s/mm), D workpiece effective thickness (mm), k workpiece shove charge condition correction factor, typically by 1.0-1.5

3), Quench heating speed

For complex-shaped, require that distortion shape is little, or the heavy casting and forging with steel alloy manufacture, it is necessary to control firing rate to ensure to reduce distorsion during quenching and tearing tendency, generally it is warmed up to 600-700 DEG C with 30-70 DEG C/h speed, heats up with 50-100 DEG C/h speed again after samming a period of time；The medium and low carbon steel of simple shape, the diameter medium carbon structural alloy steel less than 400mm can be directly to temperature and enters stove heating；

4), quenching and cooling method

Workpiece quenches in low temperature salt-bath or alkaline bath furnace, and the temperature of salt bath or alkaline bath is near Ms point, and workpiece stops 2min～5min in this temperature, then takes out air cooling, and this type of cooling is grade quench；Stricter high alloy tool steel is required for complex-shaped, distortion, it is possible to adopt multiple fractionation quenching；The purpose of gradient cooling, is to make workpiece internal and external temperature comparatively uniform, carrying out martensite transfor mation, it is possible to be greatly reduced quenching stress, it is prevented that strain cracking simultaneously；All fixing on before hierarchical temperature slightly above Ms point, workpiece internal and external temperature uniformly subsequently enters martensitic regions；Now it is improved at the temperature classification slightly below Ms point；Practice have shown that, in the better effects if of the Ms following classification of point；Such as, the grade quench in the alkaline bath of 160 DEG C of high-carbon steel mould, can harden, deform little again, so application is very extensive；

5), quenching medium

Making high-temperature-phase austenite in steel be transformed into low temperature metastable phase martensite in cooling procedure, rate of cooling have to be larger than the critical cooling rate of steel.

The present invention is simple to operate, and operator's skill requirement is low, and product quality is high.

Detailed description of the invention

Below in conjunction with embodiment, the invention will be further described:

A kind of gear quenching technique, including following operation:

1), quenching temperature

The quenching of steel is that steel is heated to critical temperature Ac3(sub-eutectoid steel) or Ac1(hypereutectoid steel) more than a certain temperature, insulation a period of time, so as to all or part of austenite 1 is changed, then carry out the Technology for Heating Processing that martensite (or bainite) changes being as cold as below Ms (or isothermal near Ms) soon more than the cooling rate of critical cooling rate；

Quenching temperature is set as 800 DEG C at this by the transformation temperature of steel；

2), the Quench heating time

Quenching Soaking Time is determined by many factors such as equipment mode of heating, accessory size, the composition of steel, batch and plant capacities；The Quench heating time should include the whole cross section of workpiece and be heated to predetermined hardening heat, and so as to complete the time needed for structural transformation, carbide dissolution and homogeneity of austenite component at such a temperature, therefore, the Quench heating time includes heating up and two periods of insulation；In actual production, only in large-scale workpiece or a lot of situation of batch, just heating-up time and temperature retention time are accounted for respectively, generally heating-up time and temperature retention time are referred to as the Quench heating time；Under concrete working condition, the Quench heating time, conventional empirical equation calculated, and finally determined by experiment, and conventional empirical equation is:

t=a×k×D

In formula, T heat time heating time (min or s), a heating coefficient (min/mm or s/mm), D workpiece effective thickness (mm), k workpiece shove charge condition correction factor, typically by 1.0-1.5

3), Quench heating speed

For complex-shaped, require that distortion shape is little, or the heavy casting and forging with steel alloy manufacture, it is necessary to control firing rate to ensure to reduce distorsion during quenching and tearing tendency, generally it is warmed up to 600-700 DEG C with 30-70 DEG C/h speed, heats up with 50-100 DEG C/h speed again after samming a period of time；The medium and low carbon steel of simple shape, the diameter medium carbon structural alloy steel less than 400mm can be directly to temperature and enters stove heating；

4), quenching and cooling method

Workpiece quenches in low temperature salt-bath or alkaline bath furnace, and the temperature of salt bath or alkaline bath is near Ms point, and workpiece stops 2min～5min in this temperature, then takes out air cooling, and this type of cooling is grade quench；Stricter high alloy tool steel is required for complex-shaped, distortion, it is possible to adopt multiple fractionation quenching；The purpose of gradient cooling, is to make workpiece internal and external temperature comparatively uniform, carrying out martensite transfor mation, it is possible to be greatly reduced quenching stress, it is prevented that strain cracking simultaneously；All fixing on before hierarchical temperature slightly above Ms point, workpiece internal and external temperature uniformly subsequently enters martensitic regions；Now it is improved at the temperature classification slightly below Ms point；Practice have shown that, in the better effects if of the Ms following classification of point；Such as, the grade quench in the alkaline bath of 160 DEG C of high-carbon steel mould, can harden, deform little again, so application is very extensive；

5), quenching medium

Making high-temperature-phase austenite in steel be transformed into low temperature metastable phase martensite in cooling procedure, rate of cooling have to be larger than the critical cooling rate of steel；

Cooling down but in process, the rate of cooling in surface and heart portion has-Ding difference, if this species diversity is sufficiently large, is then likely to result in and is partially converted to martensite more than critical cooling rate, and can not be transformed into the situation of martensite less than the heart portion of critical cooling rate；For ensureing whole cross section is all changed into the hardening media that martensite needs to select cooling capacity sufficiently strong, to ensure that there is sufficiently high rate of cooling in workpiece heart portion；But rate of cooling is big, inside workpiece uneven causes internal stress owing to expanding with heat and contract with cold, it is possible to make workpiece deformation or cracking.

Claims (1)

1. a gear quenching technique, is characterized in that: include following operation:

1), quenching temperature

The quenching of steel is that steel is heated to critical temperature Ac3(sub-eutectoid steel) or Ac1(hypereutectoid steel) more than a certain temperature, insulation a period of time, so as to all or part of austenite 1 is changed, then carry out the Technology for Heating Processing that martensite (or bainite) changes being as cold as below Ms (or isothermal near Ms) soon more than the cooling rate of critical cooling rate；

Quenching temperature is set as 800 DEG C at this by the transformation temperature of steel；

2), the Quench heating time

Quenching Soaking Time is determined by many factors such as equipment mode of heating, accessory size, the composition of steel, batch and plant capacities；The Quench heating time should include the whole cross section of workpiece and be heated to predetermined hardening heat, and so as to complete the time needed for structural transformation, carbide dissolution and homogeneity of austenite component at such a temperature, therefore, the Quench heating time includes heating up and two periods of insulation；In actual production, only in large-scale workpiece or a lot of situation of batch, just heating-up time and temperature retention time are accounted for respectively, generally heating-up time and temperature retention time are referred to as the Quench heating time；Under concrete working condition, the Quench heating time, conventional empirical equation calculated, and finally determined by experiment, and conventional empirical equation is:

t=a×k×D

In formula, T heat time heating time (min or s), a heating coefficient (min/mm or s/mm), D workpiece effective thickness (mm), k workpiece shove charge condition correction factor, typically by 1.0-1.5

3), Quench heating speed

For complex-shaped, require that distortion shape is little, or the heavy casting and forging with steel alloy manufacture, it is necessary to control firing rate to ensure to reduce distorsion during quenching and tearing tendency, generally it is warmed up to 600-700 DEG C with 30-70 DEG C/h speed, heats up with 50-100 DEG C/h speed again after samming a period of time；The medium and low carbon steel of simple shape, the diameter medium carbon structural alloy steel less than 400mm can be directly to temperature and enters stove heating；

4), quenching and cooling method

Workpiece quenches in low temperature salt-bath or alkaline bath furnace, and the temperature of salt bath or alkaline bath is near Ms point, and workpiece stops 2min～5min in this temperature, then takes out air cooling, and this type of cooling is grade quench；Stricter high alloy tool steel is required for complex-shaped, distortion, it is possible to adopt multiple fractionation quenching；The purpose of gradient cooling, is to make workpiece internal and external temperature comparatively uniform, carrying out martensite transfor mation, it is possible to be greatly reduced quenching stress, it is prevented that strain cracking simultaneously；All fixing on before hierarchical temperature slightly above Ms point, workpiece internal and external temperature uniformly subsequently enters martensitic regions；Now it is improved at the temperature classification slightly below Ms point；Practice have shown that, in the better effects if of the Ms following classification of point；Such as, the grade quench in the alkaline bath of 160 DEG C of high-carbon steel mould, can harden, deform little again, so application is very extensive；

5), quenching medium

Making high-temperature-phase austenite in steel be transformed into low temperature metastable phase martensite in cooling procedure, rate of cooling have to be larger than the critical cooling rate of steel.