CN116219140A - Post-welding heat treatment process for forge piece - Google Patents

Abstract

The invention discloses a forge piece postweld heat treatment process, which comprises the following steps: s1, placing forging: placing the forging in a heating furnace of a heat treatment process; s2, heat treatment process: when a workpiece is put into a furnace, the furnace temperature is not more than 140 ℃, the temperature of a forging piece is kept between 640 and 720 ℃ for 2 to 5 hours, the temperature is raised to 900 to 950 ℃, the temperature is kept for 4 to 6 hours, the temperature of the forging piece is not more than 450 ℃, the forging piece is cooled to 350 to 380 ℃, the cooled forging piece is put into the furnace for 320 plus or minus 20 ℃ for 6 to 10 hours, the temperature is raised to 721 plus or minus 20 ℃ by high-temperature tempering, the temperature is kept for 2 to 5 hours, the forging piece is cooled to be lower than 150 ℃ and is discharged, and the post-forging heat treatment process of the forging piece is completed; the process is suitable for the post-forging heat treatment of medium and low carbon alloy structural steels such as 45#, 40cr, 27SiMn, 42CrMo and the like, and the post-welding heat treatment process effectively reduces the generation tendency of welding cracks and improves the service life and the safety coefficient of the parts.

Description

Post-welding heat treatment process for forge piece

Technical Field

The invention relates to the technical field of heat treatment processing technology, in particular to a forge piece postweld heat treatment technology.

Background

Welding residual stress is a key problem in the field of welding engineering research. In various engineering applications involving welding, the effect of residual stresses is of great concern. For example, in the civil engineering field, for welded connection of steel structures, residual stress has an influence on fatigue performance, stable bearing capacity, and the like of the structure.

The welding residual stress refers to the internal stress of the welding part, which is generated by restraining deformation in the welding heat process and is remained in the welding structure, wherein the thermal stress generated by restraining cooling shrinkage after welding metal is melted is most remarkable, and the thermal stress is the main part of the residual stress. During welding, the welding area is locally heated and expanded, and is restrained by the part far from the welding line and can not be freely stretched, so that the welding area is pressed to generate plastic deformation, and in the subsequent cooling process, the welding area is required to be shortened than other parts, and is restrained by the part far from the welding area and can not be freely shortened, so that residual tensile stress is generated by tension. Internal stresses that occur when the internal metallographic structure changes during weld cooling are a minor part of the residual stress. The greater the rigidity of the structure, i.e. the greater the restraint, the greater the residual stresses produced, and the greater the impact on the structural load-bearing capacity.

The residual stress is in an unstable stress state, and when the forging is subjected to external force, the residual stress interacts with the forging to enable certain parts of the forging to be plastically deformed, and the internal stress of the section is redistributed; when the external force is removed, the whole forging is deformed. Therefore, the residual stress significantly affects the accuracy of the forging after machining.

Disclosure of Invention

The invention aims to provide a forge piece postweld heat treatment process for solving the problems in the background technology.

In order to achieve the above purpose, the present invention is realized by the following technical means:

a forge piece postweld heat treatment process comprises the following steps:

s1, placing forging: placing the forgings in a heating furnace of a heat treatment process, and leaving a gap between the workpieces;

s2, heat treatment process: when the workpiece is put into the furnace, the furnace temperature is not more than 140 ℃, the heating rate is less than or equal to 60 ℃/h, the temperature of the forging is 640-720 ℃, the heat preservation is carried out for 2-5h, then the temperature is raised, the heating rate is less than or equal to 60 ℃/h, the temperature is raised to 900-950 ℃, the heat preservation is carried out for 4-6 h, the cooling rate is less than or equal to 60 ℃/h, the temperature of the forging is not more than 450 ℃, the air cooling is carried out to 350-380 ℃, the forging subjected to air cooling is put into the furnace for 320+/-20 ℃ for heat preservation for 6-10h, the heating rate is less than or equal to 60 ℃/h, the high temperature tempering is raised to 721+/-20 ℃, the heat preservation is carried out for 2-5h, the cooling rate is less than or equal to 70 ℃/h, the cooling is carried out to be lower than 150 ℃, and the post-forging heat treatment process of the forging is completed.

Further, for repair welding of the forge piece, heat-insulating cotton is timely covered after welding, so that temperature loss is reduced, and thermal stress is reduced; .

Further, the process is suitable for the post-forging heat treatment of medium and low carbon alloy structural steels such as 45#, 40cr, 27SiMn, 42CrMo and the like.

Compared with the prior art, the invention has the following beneficial effects:

the process is suitable for the post-forging heat treatment of medium and low carbon alloy structural steels such as 45#, 40cr, 27SiMn, 42CrMo and the like, and can effectively reduce the generation tendency of welding cracks, greatly reduce the risk of cracking at welding seams and improve the service life and the safety coefficient of parts.

The specific embodiment is as follows:

in the present embodiment

A forge piece postweld heat treatment process comprises the following steps:

s1, placing forging: placing the forgings in a heating furnace of a heat treatment process, and leaving a gap between the workpieces;

s2, heat treatment process: when the workpiece is put into the furnace, the furnace temperature is not more than 140 ℃, the heating rate is less than or equal to 60 ℃/h, the temperature of the forging is 640-720 ℃, the heat preservation is carried out for 2-5h, then the temperature is raised, the heating rate is less than or equal to 60 ℃/h, the temperature is raised to 900-950 ℃, the heat preservation is carried out for 4-6 h, the cooling rate is less than or equal to 60 ℃/h, the temperature of the forging is not more than 450 ℃, the air cooling is carried out to 350-380 ℃, the forging subjected to air cooling is put into the furnace for 320+/-20 ℃ for heat preservation for 6-10h, the heating rate is less than or equal to 60 ℃/h, the high temperature tempering is raised to 721+/-20 ℃, the heat preservation is carried out for 2-5h, the cooling rate is less than or equal to 70 ℃/h, the cooling is carried out to be lower than 150 ℃, and the post-forging heat treatment process of the forging is completed.

Further, for repair welding of the forge piece, heat-insulating cotton is timely covered after welding, so that temperature loss is reduced, and thermal stress is reduced; .

Further, the process is suitable for the post-forging heat treatment of medium and low carbon alloy structural steels such as 45#, 40cr, 27SiMn, 42CrMo and the like.

And placing the sizing block at the bottom of the 27SiMn shaft forging in a heating furnace for post-welding heat treatment.

Example 1

A forge piece postweld heat treatment process comprises the following steps:

s1, placing forging: the bottom of the 27SiMn shaft forging is provided with a sizing block which is placed in a heating furnace of a heat treatment process, and a gap is reserved between the workpieces;

s2, heat treatment process: when the workpiece is put into the furnace, the furnace temperature is not more than 140 ℃, the heating rate is 55 ℃/h, the temperature of the forging is 650 ℃, the temperature is kept for 4 hours, then the temperature is raised, the heating rate is 55 ℃/h, the temperature is raised to 910 ℃, the temperature is kept for 5 hours, the cooling rate is 55 ℃/h, the temperature of the forging is not more than 450 ℃, the forging is cooled to 370 ℃, the cooled forging is put into the furnace for 330 ℃ for 8 hours, the heating rate is 55 ℃/h, the high-temperature tempering is raised to 731 ℃, the cooling rate is 65 ℃/h after the temperature is kept for 4 hours, the forging is cooled to be lower than 150 ℃, and the post-forging heat treatment process of the forging is completed.

Example two

A forge piece postweld heat treatment process comprises the following steps:

s1, placing forging: the bottom of the 27SiMn shaft forging is provided with a sizing block which is placed in a heating furnace of a heat treatment process, and a gap is reserved between the workpieces;

s2, heat treatment process: when the workpiece is put into the furnace, the furnace temperature is not more than 140 ℃, the heating rate is 55 ℃/h, the temperature of the forging is 680 ℃, the temperature is kept for 4 hours, then the temperature is raised, the heating rate is 55 ℃/h, the temperature is raised to 920 ℃, the temperature is kept for 5 hours, the cooling rate is 55 ℃/h, the temperature of the forging is not more than 450 ℃, the forging is cooled to 370 ℃, the cooled forging is put into the furnace 335 ℃ for 9 hours, the heating rate is 55 ℃/h, the high-temperature tempering is raised to 731 ℃, the cooling rate is 65 ℃/h after the temperature is kept for 4 hours, the forging is cooled to be lower than 150 ℃, and the post-forging heat treatment process of the forging is completed.

Example III

A forge piece postweld heat treatment process comprises the following steps:

s1, placing forging: the bottom of the 27SiMn shaft forging is provided with a sizing block which is placed in a heating furnace of a heat treatment process, and a gap is reserved between the workpieces;

s2, heat treatment process: when the workpiece is put into the furnace, the furnace temperature is not more than 140 ℃, the heating rate is 55 ℃/h, the temperature of the forging is 700 ℃, the temperature is kept for 4 hours, then the temperature is raised, the heating rate is 55 ℃/h, the temperature is raised to 930 ℃, the temperature is kept for 5 hours, the cooling rate is 55 ℃/h, the temperature of the forging is not more than 450 ℃, the forging is cooled to 370 ℃, the cooled forging is put into the furnace 335 ℃ for 9 hours, the heating rate is 55 ℃/h, the high-temperature tempering is raised to 740 ℃, the cooling rate is 65 ℃/h after the temperature is kept for 4 hours, the forging is cooled to be lower than 150 ℃, and the post-forging heat treatment process of the forging is completed.

The mechanical properties parameters of the post-weld treatment of the SiMn shaft forgings of each example 27 are shown in the following table:

the disclosed embodiments fall within the scope of the appended claims, and are intended to be illustrative of the scope of the invention as defined by the claims, which should not be construed as limiting the scope of the claims.

When values or ranges of values, preferred ranges or a list of lower and upper preferred values are provided, it is to be understood that any range formed from any smaller range limit or preferred value and any pair of values for any larger range limit or preferred value, whether or not the ranges are separately disclosed. Where the specification describes a numerical range, unless the specification states otherwise, the range is intended to include both the end of the range and all integers and fractions within the range.

When the terms "about" or "about" are used to describe the end of a numerical value or range, the disclosure should be interpreted to include the particular numerical value or end of the range concerned.

The use of "a" and "an" are used to describe elements of the invention for convenience and to give a general description of the invention. Unless explicitly stated otherwise, the description should be understood as including one or at least one.

Claims (2)

1. A forge piece postweld heat treatment process is characterized in that: the method comprises the following steps:

s1, placing forging: placing the forgings in a heating furnace of a heat treatment process, and leaving a gap between the workpieces;

s2, heat treatment process: when the workpiece is put into the furnace, the furnace temperature is not more than 140 ℃, the heating rate is less than or equal to 60 ℃/h, the temperature of the forging is 640-720 ℃, the heat preservation is carried out for 2-5h, then the temperature is raised, the heating rate is less than or equal to 60 ℃/h, the temperature is raised to 900-950 ℃, the heat preservation is carried out for 4-6 h, the cooling rate is less than or equal to 60 ℃/h, the temperature of the forging is not more than 450 ℃, the air cooling is carried out to 350-380 ℃, the forging subjected to air cooling is put into the furnace for 320+/-20 ℃ for heat preservation for 6-10h, the heating rate is less than or equal to 60 ℃/h, the high temperature tempering is raised to 721+/-20 ℃, the heat preservation is carried out for 2-5h, the cooling rate is less than or equal to 70 ℃/h, the cooling is carried out to be lower than 150 ℃, and the post-forging heat treatment process of the forging is completed.

2. A forge piece postweld heat treatment process is applied to postforge heat treatment of low-carbon alloy structural steel in 45#, 40cr, 27SiMn and 42 CrMo.