This standard specifies the post-weld heat treatment methods for carbon steel and low alloy steel welded components. This standard applies to post-weld heat treatment of carbon steel and low alloy steel products of boilers and pressure vessels, with the main purpose of improving joint performance and reducing welding residual stress. The post-weld heat treatment of other products can also be implemented by reference. JB/T 6046-1992 Post-weld heat treatment method for carbon steel and low alloy steel welded components JB/T6046-1992 Standard download and decompression password: www.bzxz.net

Machinery Industry Standards of the People's Republic of China
Carbon steel and low alloy steel welded components
Post-weld heat treatment methods
1 Subject content and applicable scope
This standard specifies the carbon Post-weld heat treatment methods for steel and low-alloy steel welded components. JB/T 6046-92
This standard applies to post-weld heat treatment of carbon steel and low alloy steel products of boilers and pressure vessels, with the main purpose of improving joint performance and reducing welding residual stress. The post-weld heat treatment of other products can also be implemented by reference. 2 Reference standards
GB150
Steel pressure vessels
GB3375 Welding terminology
GB7232 Metal heat treatment process terminology
GB9452 Determination method of effective heating zone of heat treatment furnace GBJ94 Spherical Relay Construction and Acceptance Specifications
Technical Conditions for Welding of Boiler Pressure Components
JB1613
3 Terms
"Post-weld heat treatment", *Local heat treatment" terminology definition According to the regulations of GB3375 and GB7232 respectively, the heat treatment in the furnace is to put the heated object into the heat treatment furnace at one time. During the heat treatment in the segmented heat treatment furnace, due to conditions, the heated object cannot be placed into the furnace at one time. The heat treatment is carried out in multiple stages in the furnace based on the conditions.
The overall heat treatment outside the furnace is a heat treatment in which the heated parts are heated as a whole outside the furnace during the manufacturing process. For welding areas and mother villages that are repeatedly heated, in order to ensure welding quality and joint performance, heat treatment is carried out at a lower temperature during the welding process 4. Process requirements for post-explosion heat treatment
4.1 Tonggang||tt| |4.1.1 Management of post-weld heat treatment
The management content of post-weld heat treatment includes:
a.
b.
Selection of heat treatment methods and equipment,|| tt||Detection of temperature or furnace temperature of heated parts:
Guarantee and inspection of appearance quality, shape, size of heated parts; record of post-weld heat treatment!
d.||tt| |e.
4.1.2
Considerations of other factors that may affect the heat treatment effect. Selection of post-weld heat treatment process specifications
Approved by the Ministry of Mechanical and Electronics Industry of the People's Republic of China on 1992-05-05. 1993-07-01 Implementation
417
JB/T6046-92
When performing post-weld heat treatment, the base metal, welding materials, and service status of the welded structure should be fully considered. Based on many factors such as process specifications and structural characteristics, and based on product-related design and manufacturing regulations, technical conditions or process evaluation results, the process specifications for post-weld heat treatment are specifically specified
The heat treatment process specifications generally include:
Insulation temperature and its allowable range;
a.
For the selection of insulation temperature, please refer to Excerpt A (Supplement) b. Insulation time:
Insulation time. See Appendix A for the selection.
c. Heating speed;
During the heating process, the heating speed should be controlled generally within the temperature range above 400℃ (can be 300℃ under special conditions). For heat treatment in the furnace and local heat treatment, the heating rate should meet the following requirements: R, ≤220×25/8, and the maximum does not exceed 220℃/h. Where: Ri——heating rate, C/h;
mother Thickness of material, mm
For overall outside-furnace heat treatment, the heating speed should be controlled below 80°C/h. d. Cooling speed;
During the cooling process, the cooling speed should be controlled generally in the temperature range above 400℃ (300℃ under special conditions). For heat treatment in the furnace and local heat treatment, the cooling rate should meet the following requirements: Rz≤275×25/8, and the maximum should not exceed 275℃/h. Where: R2-cooling rate, ℃/h.
For overall outside-furnace heat treatment, the cooling rate should be controlled within the range of 30~50℃/h. The temperature difference between the heated parts.
e.
During the heating and cooling process, the maximum temperature difference of the heating part of the heated part within the range of 4500mm shall not exceed 130℃. During the heat preservation process, for heat treatment in the furnace, the maximum temperature difference between the heated parts should not exceed 50°C. For overall heat treatment outside the furnace and local heat treatment, within the specified effective heating range, the maximum temperature difference between the heated parts should not exceed 50°C. The maximum temperature difference between locations should generally not exceed 85°C. 4.1.3 Selection of heating device
The heating device should meet the following requirements:
a.
can meet the process requirements of heat treatment;
b.
During the heat treatment process, there is no harmful effect on the heated part; c
can ensure that the heated part of the heated part is evenly heated: after the heated part is heat treated, its deformation can meet the design and use requirements, d .
Able to accurately measure and control temperature
e.
4.1.4 Heat treatment requirements for dissimilar steel welded joints When heat treating dissimilar steel welded joints, the heat treatment should generally be based on the base metal The specifications of the process requirements are carried out. At the same time, the properties of the parent materials on both sides of the joint should also be comprehensively considered.
4.1.5 Heat treatment requirements for welded joints between pressure components and non-pressure components When heat treatment is performed on welded joints between pressure components and non-pressure components, the heat treatment process specifications for pressure components should generally be carried out. 4.2 Construction requirements
4.2.1 Furnace heat treatment
For products with post-weld heat treatment requirements, the furnace heat treatment method should be selected as much as possible. When performing heat treatment in the furnace, on the basis of meeting 4.1, it should also be noted that the heat treatment furnace should meet the relevant regulations of GB9542. If the corresponding relationship between the furnace temperature and the temperature of the heated part is accumulated, it is generally allowed to use the furnace temperature to estimate the temperature of the heated part during heat treatment. However, for special or important welding products, the temperature measurement should generally be based on the thermocouple installed on the heated part; JB/T6046-92
b. The heated parts should be neatly placed in the effective heating area of ??the heat treatment furnace. Avoid direct flame injection into the workpiece, and ensure uniform heat flow in the furnace. In order to prevent the occurrence of restraining stress and deformation, attention should also be paid to the reasonable placement of the supports of the heated parts; c. The temperature in the furnace when the heated parts are placed in or out of the furnace should generally not exceed 400°C. However, for heated parts with large thickness differences, complex structures, high dimensional stability requirements, and low residual stress requirements, the temperature in the furnace when the heated parts are placed in or out of the furnace should generally not exceed 300℃.
4.2.2 Segmented heat treatment
When performing segmented heat treatment, on the basis of meeting 4.1, it should also be noted that when the heated parts are segmented into the furnace for heat treatment, the repeatedly heated parts should be Greater than 1500mm; a
Appropriate insulation measures should be taken for the outer part of the furnace to be heated to avoid adverse effects caused by excessive temperature gradient, b.
center. The supports should be reasonably placed outside the furnace to avoid harmful thermal expansion and contraction. 4.2.3 Overall outside-furnace heat treatment bZxz.net
When performing overall outside-furnace heat treatment, on the basis of meeting 4.1, attention should also be paid to: considering the adverse effects of climate change, unexpected power outages and other factors on heat treatment and emergency measures ;Necessary measures should be taken to ensure the uniformity and stability of the temperature of the heated parts, and to avoid restraint stress and deformation of the heated parts, support structures, bases, etc. due to thermal expansion and contraction b,
C. The measurement of thermal insulation and temperature can be carried out according to the relevant provisions of GBJ94. 4.2.4 Local heat treatment
When performing local heat treatment, on the basis of meeting 4.1, it should also be noted that: appropriate insulation measures should be taken for the non-heated parts close to the heating area to ensure the temperature gradient of the heated parts No harmful a
effects,
b. When performing local heat treatment on the annular seam on the shell or the annular seam connecting the shell and the head, the entire circumference of the container including the annular seam should be heated to the required temperature. According to specific product requirements, the width of the annular heating belt on each side of the annular seam should be 2 to 3 times greater than the wall thickness of the container; c. When performing local heat treatment on the welds connecting nozzles or other accessories to the shell or head, the entire circumference of the vessel including nozzles or other accessories should be heated evenly to the required temperature. According to specific product requirements, the width of the annular heating belt is calculated from the weld connecting the pipe or other accessories to the container, and should be at least 3-6 times the wall thickness of the container. 4.2.5 Intermediate heat treatment
When intermediate heat treatment is required between the welding processes, refer to 4.1 and 4. based on the selected heat treatment method.The relevant provisions of Article 2 shall be implemented.
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JB/T6046—92
Fu Kang A
Post-weld heat treatment process specifications for commonly used steel types (supplement)
A1 Commonly used steels Please refer to Table A1 for the post-weld heat treatment process specifications. Table A1
Insulation temperature”》
Group
P15)
P25)
P3
P4
P5| |tt||Examples of steel types
Q235
20
12Mn
16Mn
15Mny
15MnVN
09Mn2V| |tt||16MnDR
09Mn2VDR
14MnMoy
15MnMoV
1&MnMoNb
20MnMoNb
20MnMo
13MnNiMoNbz||tt ||12CrMo
15CrMo
12Cr1MoV
12Cr2Mo
12Cr2Mol
12Cr2MoW VTiB
℃
550||tt| |:600
≥670
Recommended amount based on thickness, h≤50mm
$/25.
but not less than 1/4
8>50~125mm
8>125mm
(150+8)/100
8/25, but not less than 1/4||tt| |(375+$)/100
Note: 1) The classification of group numbers does not mean that the thermal insulation properties of the same base material with different P values ??can be selected arbitrarily. In order to determine a reasonable insulation temperature, appropriate process evaluation should be carried out when necessary.
2This steel type has not yet been included in the steel standards, but it is listed in GB150. 3) When performing post-weld heat treatment on quenched and tempered steel, the insulation temperature should generally be lower than the tempering strength of the steel. However, for post-weld heat treatment where the holding temperature is higher than the tempering temperature and the performance of the steel can still meet the product use requirements, there is no restriction. 4) The meaning of thickness should be: E.
b.
.
d.
e.
The thickness of the thinner parts when the shell and head are butted; the thickness of the shell welded to flanges, tube sheets or other similar structures; the thickness of the shell or head welded to the nozzle; the welding of non-pressure parts and pressure parts The thickness of the weld at the joint: the depth of the repair weld.
5) Due to limitations of objective conditions, when the P1 and P2 group steel cannot be subjected to post-weld heat treatment at the temperature specified in this table, it is allowed to be used according to the specific circumstances when necessary 420
JB/T6046-92
Perform post-weld heat treatment by appropriately extending the holding time at a lower temperature (not less than 500°C). 6) The protection time can be calculated cumulatively.
Appendix B
Post-weld heat treatment process record most
(reference part)
B1 Post-weld heat treatment process record format is shown in Table B1. Table B1
Product number
Heat treatment date
Feet
inch
Insulation temperature
Heating speed
Heating method| |tt||Human furnace temperature
Process curve
Responsible engineer
Additional instructions:
Inspector
Product name
Material
Quality
Heat treatment method
Heating time
Cooling degree
Cooling method
Oil temperature
Construction personnel| |tt||This standard is proposed and administered by the Harbin Welding Research Institute of the Ministry of Mechanical and Electronic Industry. This standard is drafted by Harbin Welding Research Institute. This standard was mainly drafted by Park Dongguang, Zhang Baode and Fang Weimin. 421
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