Forging Guidelines for Tubesheet: Mn-Ni-Mo Steel Forgings for PWR Steam Generator Tube Plates

What are Mn-Ni-Mo Steel Forgings for PWR Steam Generator Tube Plates?

In nuclear power generation, PWR (Pressurized Water Reactor) steam generators are critical in converting heat from nuclear fission into steam. These steam generators consist of various components, including tube plates that support the numerous tubes carrying the heated water. To ensure the reliable and safe operation of PWR steam generators, the material used for tube plates must possess exceptional strength, corrosion resistance, and thermal properties. This is where Mn-Ni-Mo steel forgings come into play.

What are PWR Steam Generator Tube Plates?

PWR steam generator tube plates are large structural components located at the bottom of steam generators in nuclear power plants. These plates act as a foundation, supporting the many tubes that carry the primary coolant water. The tube plates must withstand high pressure, temperature variations, and corrosive conditions while ensuring the integrity of the steam generator system.

What are Mn-Ni-Mo steel forgings?

Mn-Ni-Mo steel forgings are highly specialized components with extensive application in PWR steam generator tube plates. These forgings are meticulously crafted using a combination of manganese (Mn), nickel (Ni), and molybdenum (Mo) to achieve a unique set of properties that make them ideal for this critical role.

The Significance of Mn-Ni-Mo Steel Forgings

Mn-Ni-Mo steel forgings play a vital role in PWR steam generator tube plates due to their exceptional mechanical properties and corrosion and thermal stress resistance. These forgings offer high strength, excellent ductility, and toughness, making them capable of withstanding the demanding operating conditions of nuclear power plants.

Composition of Mn-Ni-Mo Steel Forgings

Mn-Ni-Mo steel forgings are typically composed of varying percentages of manganese, nickel, molybdenum, and other alloying elements to enhance specific properties. The exact composition may vary based on the requirements and standards of regulatory bodies and industry specifications. The carefully balanced composition ensures the forgings’ desired strength, toughness, and corrosion resistance.

Manufacturing process guide for manganese nickel molybdenum steel forgings for steam generator tube sheets

The manufacturing process guide of this forging specifies the requirements for manufacturing, testing, inspection, and acceptance of manganese nickel molybdenum steel forgings for steam generator tube sheets of pressurized water reactor nuclear power plants. The manufacturing process guide of this forging applies to 18MnNiMo and 20MnNiMo alloy steel forgings for steam generator tubesheet of pressurized water reactor nuclear power plants.

Normative references for manganese nickel molybdenum steel forgings

• GB/T 223 Chemical Analysis Methods for Steel and Alloy.

• GB/T 228.1-2010 Metallic Materials – Tensile Testing – Part 1: Room Temperature Test Method (ISO6892-1:2009 MOD).

• GB/T 228.2-2015 Metallic Materials – Tensile Testing – Part 2: High Temperature Test Method (ISO6892-2:2011MOD).

• GB/T 4336 Method for Spark Source Atomic Emission Spectrometric Analysis of Carbon Steel and Medium and Low Alloy Steel (Conventional Method).

• GB/T 11261 Determination of Oxygen Content in Steel – Pulse Heating Inert Gas Melting Infrared Absorption Method.

• GB/T 14265 General Rules for Analysis of Hydrogen, Oxygen, Nitrogen, Carbon, and Sulfur in Metal Materials.

• GB/T 16702-2019 Code for Design of Nuclear Island Mechanical Equipment of pressurized water reactor Nuclear Power Plant.

• GB/T 20066 Methods for Sampling and Preparation of Samples for Determining Chemical Composition of Steel and Iron (GB/T 20066-2006, ISO14284:1996, IDT）.

• GB/T 20123 Determination of Total Carbon and Sulfur Content in Steel – Infrared Absorption Method after High Frequency Induction Furnace Combustion (Conventional Method) (GB/T

• 20123-2006, ISO15350: 2000, IDT）.

• GB/T 20124 Determination of Nitrogen Content in Steel – Inert Gas Fusion Thermal Conductivity Method (Conventional Method).

• GB/T 20125 Low alloy steel Determination of multi-element content inductively coupled plasma atomic emission spectrometry.

• NB/T 20003.2-2010 Non-destructive Testing of Nuclear Island Mechanical Equipment in Nuclear Power Plants – Part 2: Ultrasonic Testing.

• NB/T 20003.4-2010 Nondestructive Testing of Nuclear Island Mechanical Equipment in Nuclear Power Plants – Part 4: Penetrant Testing.

• NB/T 20003.5-2010 Nondestructive Testing of Nuclear Island Mechanical Equipment in Nuclear Power Plants – Part 5: Magnetic Particle Testing.

• NB/T 20003.7-2010 Nondestructive Testing of Nuclear Island Mechanical Equipment in Nuclear Power Plants – Part 7: Visual Testing.

• NB/T 20004-2014 Physical and Chemical Inspection Methods for Mechanical Equipment Materials of Nuclear Power Plant Nuclear Island.

• NB/T 20328.4 Nondestructive Testing of Nuclear Island Mechanical Equipment in Nuclear Power Plants – Part 4: Penetrant Testing.

• NB/T 20328.5 Nondestructive Testing of Nuclear Island Mechanical Equipment in Nuclear Power Plants – Part 5: Magnetic Particle Testing.

Manufacturing of manganese nickel molybdenum steel forgings

Product and Workshop Evaluation

Suppose there are requirements in the order contract or forging technical specifications before the first production of forgings. In that case, the forging manufacturer shall conduct product and workshop evaluations by the requirements of Appendix M of GB/T 16702-2019.

Manufacturing documents

Forging manufacturers should prepare a manufacturing outline before production, listing the main processes and technical parameters that directly affect the quality of forgings and providing detailed explanations. The manufacturing outline should at least include the following:

• a) Raw materials;
• b) Smelting;
• c) The specified value of chemical composition;
• d) The quality and type of steel ingots;
• e) Percentage of steel ingot head and tail removal;
• f) Schematic diagram of the position of forgings in steel ingots;
• g) A schematic diagram of the blank with dimensions marked after each forging process, including the forging ratio and total forging ratio;
• h) Outline drawing of forging blank, heat treatment outline drawing, non-destructive testing outline drawing, and delivery part outline drawing;
• i) Intermediate heat treatment and final heat treatment (performance heat treatment);
• j) Location diagram of the test material used for acceptance testing on the forging;
• k) The position map of the sample on the test portion.

The main manufacturing and inspection processes should be listed chronologically, including smelting, forging, machining, heat treatment, sampling and inspection, and non-destructive testing.

Smelting process of raw materials

Electric furnace steelmaking with aluminum killed and vacuum degassing or other equivalent smelting processes should be used.

Forging of manganese nickel molybdenum steel forgings

The steel ingot should ensure a sufficient cutting amount to remove shrinkage and major segregation. The steel ingot’s weight and the cutting amount percentage should be recorded.

The total forging ratio of forgings calculated according to Appendix M of GB/T 16702-2019 should be greater than 3.

Machining of Manganese Nickel Molybdenum Steel Forgings

Before the performance of heat treatment
Before performance heat treatment, the overall dimensions of the forging heat treatment (which should be given in the manufacturing outline) should be as close as possible to the overall dimensions of the delivered parts.
After the performance of heat treatment
After performance heat treatment, the forgings should be machined to the delivery state and overall dimensions before final ultrasonic testing. The surface roughness of forgings should meet the requirements of non-destructive testing.

Heat treatment of manganese nickel molybdenum steel forgings

• Forgings should be delivered in a heat-treated state. This heat treatment, also known as performance heat treatment, should include the following steps: austenitizing (taking a certain temperature between 850 ℃ and 925 ℃);
• Immersion quenching;
• To achieve the required performance, a certain temperature is selected for tempering, followed by cooling in still air. The nominal insulation temperature for tempering is between 635 ℃ and 665 ℃, and the tempering insulation time should be at least 1 hour per 50mm of the maximum cross-sectional thickness.

The heat treatment conditions should be specified in the manufacturing outline, including heating rate, insulation temperature, insulation time, and cooling method.
Temperature measurement should be done using thermocouples placed on forgings, with at least 2 thermocouples (at different positions) placed on each forging. The position of the thermocouple should be indicated in the manufacturing outline. During the quenching, austenitizing, and tempering insulation stages, the maximum deviation between the actual and nominal insulation temperatures is ± 10 ℃.
Forgings are not allowed to be shaped without the purchaser’s consent.
The forging manufacturer shall evaluate the heat treatment records.
If the component needs to be reheated (see 6.2), it should be reheated according to the abovementioned regulations.
Simulated post-weld heat treatment
After the performance heat treatment of the forging, the test pieces shall be cut from the parts described in 5.2. The mechanical performance and metallographic inspection test pieces shall be subjected to simulated post-weld heat treatment.
The nominal insulation temperature range for simulated post-weld heat treatment should be consistent with the recognized highest temperature range during the manufacturing process, with a maximum deviation of ± 5 ℃ for insulation temperature. When the test material is fed into the furnace, the temperature shall not exceed 400 ℃, and the temperature rise and cooling rate at 400 ℃ shall not exceed 55 ℃/h. The simulated post-weld heat treatment insulation time should be at least 80% of the cumulative insulation time of the actual post-weld heat treatment of the forging. The simulated post-weld heat treatment records should include heat treatment temperature, insulation time, heating, and cooling rates, etc.

Rough machining dimensions of forgings

The overall dimensions of the delivered parts should be as close as possible. With the purchaser’s approval, it can weld nonstructural attachments and temporary attachments on the base material for rough machining and temporary welding of forgings.
Suppose it is necessary to weld nonstructural and temporary attachments on the forging. In that case, the forging manufacturer shall submit a drawing to the purchaser indicating the welding position and the dimensions of all temporary attachments. After the purchaser approves, the manufacturing plant shall conduct evaluation, welding, and dismantling by regulations.

Chemical composition of manganese nickel molybdenum steel forgings

Required values

The results of melting and chemical composition analysis of 18MnNiMo and 20MnNiMo steel products should comply with the provisions of Table 1.

If multiple furnaces combined casting ingots are used, the weighted average value of each furnace’s molten steel composition is used as the melting analysis value.

Table.1 Chemical Composition (Unit: wt% by Mass)

Element	18MnNiMo		20MnNiMo
	Heat analysis	Finished product analysis	Heat analysis	Finished product analysis
C	≤0.20	≤0.22	≤0.25	≤0.25
Si	0.10-0.30	0.10–0.30	0.15–0.40	0.15–0.40
Mn	1.15-1.60	1.15–1.60	1.20–1.50	1.12–1.58
P	≤0.012	≤0.012	≤0.015	≤0.018
S	≤0.012	≤0.012	≤0.005	≤0.005
Ni	0.50–0.80	0.50–0.80	0.60–1.00	0.57–1.03
Mo	0.45–0.55	0.43–0.57	0.45–0.60	0.40–0.60
Cr	≤0.25	≤0.25	0.10–0.25	0.10–0.25
V	≤0.01	≤0.01	≤0.02	≤0.02
Cu	≤0.20	≤0.20	≤0.15	≤0.15
Al	≤0.04	≤0.04	≤0.025	≤0.025
Co	—	Provide data	≤0.25	≤0.25
Nb	—	Provide data	≤0.01	≤0.01
Ca	—	Provide data	≤0.015	≤0.015
Ti	—	Provide data	≤0.015	≤0.015
B	—	Provide data	≤0.003	≤0.003
As	—	Provide data	—	Provide data
Sn	—	Provide data	—	Provide data
Sb	—	Provide data	—	Provide data
H	—	≤0.00008	—	—
O	—	Provide data	—	Provide data
N	—	Provide data	—	Provide data
a When vacuum carbon deoxidation is used, the Si content should not exceed 0.10%.

Chemical composition analysis

Chemical analysis sampling should be carried out in accordance with the provisions of GB/T 20066. Chemical analysis should be conducted in accordance with the applicable parts of GB/T 223 and/or the provisions of GB/T 4336, GB/T 11261, GB/T 14265, GB/T 20123, GB/T 20124, and GB/T 20125. The arbitration test method for chemical analysis shall be carried out in accordance with the provisions of the applicable parts of GB/T 223.

The forging manufacturer should provide a chemical composition report for melting analysis and two chemical composition reports for finished product analysis. One is for analyzing the sample taken from the top of the ingot, and the other is for analyzing the sample taken from the bottom. Finished product analysis can be conducted by sampling the remaining material after cutting mechanical test samples.

When specified in the order contract or forging procurement specification, data on the welding reheat crack sensitivity coefficient △ G and carbon equivalent C_eq calculated based on the analysis results of the finished product shall be provided. The acceptance criteria shall be determined through negotiation between the purchaser and the forging manufacturer. The calculation formula is as follows:

• a) △G=3.3[Mo%]+[Cr%]+8.1[V%]-2;

• b) C_eq=C%+Si%/24+Mn%/6+Ni%/40+Cr%/5+Mo%/4+V%/14.

Mechanical properties of manganese nickel molybdenum steel forgings

Specified values

The mechanical properties of 18MnNiMo and 20MnNiMo forgings should comply with the provisions of Table 2.

Table.2 Mechanical Properties

Test items	Test temperature	Mechanical	Specified value
			18MnNiMo		20MnNiMo
			Radial (transverse)	Circumferential (vertical)	Radial (transverse)	Circumferential (vertical)
Tensile test	Room temperature	Rp0.2/MPa	—	≥420	—	≥450
		Rm/MPa	—	580~700	—	620~795
		A/%	—	≥18	—	≥16
		Z/%	—	Provide data	—	≥35
	350°C	Rp0.2/MPa	—	≥350	—	≥370
		Rm/MPa	—	≥522	—	≥559
		A/%	—	Provide data	—	—
		Z/%	—	Provide data	—	—
Impact test	0°C	KV2/J (Average)	≥80	≥80	—	—
		KV2/J (Bounce valuea)	≥60	≥60	—	—
	-20°C	KV2/J (Average)	≥40	≥40	≥48	—
		KV2/J (Bounce valuea)	≥28	≥28	≥41	—
		Lateral expansion value LE/mm	—	—	Provide data	—
	20°C	KV2/J (Bounce valuea)	≥72	≥72	—	—

Horizontal: perpendicular to the main deformation direction; Longitudinal: parallel to the main deformation direction.
^b Only one sample in each group of three is allowed to have a result lower than the average value specified in the table.

Sampling

The test material should be cut at the X and Y positions opposite the circumferential direction of the test ring on the extension section of the forging. The extension section should be located at the bottom of the steel ingot. The sampling location is shown in the schematic diagram in Appendix A of this section.

After performance heat treatment, the test piece should be cut from the forged piece and clearly marked and marked with its radial and circumferential directions.

The test sample should have sufficient size to capture all the samples required for testing and retesting.

The forging drawing should specify the surface of the finished product that bears high tensile stress. When cutting test specimens, it should be ensured that the longitudinal axis of the specimen is at least equal to the maximum distance from the specified high tensile stress finished product surface to the nearest heat-treated surface and that the centerline of the specimen length is at least twice the distance from other heat-treated surfaces. In any case, the distance from the longitudinal axis of the specimen to any heat-treated surface of the forging shall not be less than 19mm, and the distance from the centerline of the specimen length to any second surface shall be at least 38mm.

The bottom line of the impact specimen notch should be perpendicular to the upper and lower surfaces of the forging.

If the forging needs to undergo re-heat treatment, the new specimen should be cut from the other two radially opposite X and Y positions and should be cut after re-heat treatment.

The manufacturing outline should include the position diagram of the test piece on the forging and the dimensional diagram of the sample on the test piece (see 3.2).

Testing

Test items, number of samples, and test conditions

Except for the heat treatment carried out with the forging in the delivery state, the sample representing the delivery state of the forging should be taken from the sample that has been cut off and no longer undergone heat treatment. The sample representing the simulated stress relief heat treatment state should be taken from the sample that has been simulated stress relief heat treatment. The number of samples, sampling direction, and test temperature should comply with the provisions of Table 3.

Table.3 Mechanical Property Test Items, Sample Quantity, and Test Conditions

Test items	Sample status	Sampling Direction	Test temperature/°C	Number of samples for each test portion
				X	Y
Tensile test	HTMP+SSRHT	Circumferential	Room temperature	1	1
	HTMP+SSRHT	Circumferential	350	1	1
Impact test a	HTMP+SSRHT	Circumferential	0	3	3
	HTMP+SSRHT	Circumferential	-20	3	3
	HTMP+SSRHT	Circumferential	20	3	3
	HTMP+SSRHT	Radial	0	3	/
	HTMP+SSRHT	Radial	-20	3	3b
	HTMP+SSRHT	Radial	20	3	/
Note: HTMP – Performance Heat Treatment; SSRHT – Simulated stress relief heat treatment.
a. The sampling direction for impact testing is determined according to the assessment requirements in Table 2.
b. Only applicable to 20MnNiMo forgings.

RT_NDT temperature measurement

Forgings should undergo RT_NDT temperature measurement, and the test requirements and acceptance criteria are shown in Appendix B of this section.

Test under simulated stress relief heat treatment state

Simulated stress relief heat treatment should be conducted separately in a laboratory heat treatment furnace according to the process provided by the purchaser.

The basic requirements for the simulated stress relief heat treatment process are as follows:

• The nominal insulation temperature (accurate to ± 5 ℃) should be determined in this way: the corresponding temperature range should be consistent with the highest recognized temperature range during the manufacturing process;
• The insulation time of simulated stress relief heat treatment should exceed at least 80% of the total insulation time of multiple welding stress relief heat treatments carried out during the manufacturing process of pressure vessels and the time required for supplementary heat treatment during the steam generator manufacturing process should also be considered;
• To prevent deformation and thermal stress, the heating and cooling rates should be slow enough, and in no case should the heating and cooling rates above 400 ℃ exceed 55 ℃/h.

The mechanical properties after simulated stress relief heat treatment should meet the provisions of Table 2.

Test methods

Room temperature and high-temperature tensile test

The shape and size of the sample should comply with the requirements of sample R4 in Table D.1 of Appendix D of GB/T 228.1-2010.

The room temperature tensile test shall be carried out by the provisions of GB/T 228-2010.

The high-temperature tensile test shall be carried out by the provisions of GB/T 228.2-2015. During the test, it is recommended to select a strain rate of 0.0042min-1 from the beginning of the test until reaching the yield strength, with a relative error of ± 20%; After the yield strength, the recommended strain rate is 0.084min-1, with a relative error of ± 20%; The transition from testing yield strength to testing tensile strength should be smooth to avoid overshoot.

The tensile test should record the following values:

• Yield strength R_p0.2, MPa under the condition of nonproportional elongation of 0.2%;
• Tensile strength Rm, MPa;
• Elongation after fracture A,%;
• Reduction of area Z,%.

Impact test

The impact specimen should meet the requirements of the V-notch standard specimen specified in NB/T 20004-2014. Each set of impact tests should consist of three adjacent specimens.

The impact test shall be carried out by the provisions of NB/T 20004-2014, and the shear section ratio and lateral expansion value shall be measured as data.

Retesting and Reheat Treatment of Manganese Nickel Molybdenum Steel Forgings

Retest

Room temperature and high-temperature tensile test
If the test results are unqualified due to physical defects in the sample, improper clamping, or malfunction of the testing machine, the sample should be taken again for testing. If the second test is qualified, the forging should be accepted. Otherwise, the following regulations should be followed.
If the above reasons do not cause the unqualified test results, double samples should be taken from each unqualified result for retesting.
The retest sample should be taken from the adjacent area of the unqualified sample. If the retest result is qualified, the forging should be accepted. Otherwise, it should be rejected (see 6.2).
Impact test
If the average of the test results of three samples meets the requirements, and only one sample has a test result smaller than the individual minimum value, retesting is allowed.
The retest should take 2 samples from the adjacent area of the unqualified sample. The test results of each retest sample should be greater than or equal to the specified minimum average value.

Reheat treatment

When forging is rejected due to one or more unqualified mechanical property test results, it can be reheated and treated. The conditions for reheat treatment should be included in the test report. In this case, the sample should also be cut according to the provisions of 5.2, and the test should also be carried out according to the provisions of 5.3, 5.4, and 6.1.
Reheat treatment should be done at most two times.

Metallographic inspection of manganese nickel molybdenum steel forgings

Metallographic structure
Inspect the metallographic structure of the sample according to NB/T 20004-2014 and provide metallographic images.
Grain size
The austenite grain size of forgings after performance heat treatment shall be determined in accordance with NB/T 20004-2014, and the grade shall not be lower than Grade 5.
Nonmetallic inclusions
According to the regulations of NB/T 20004-2014, non-metallic inclusions in forgings shall be inspected, and Class A, B, C, and D non-metallic inclusions (coarse and fine) shall not be greater than Class 1.5, respectively.
Sampling for metallographic examination
The metallographic examination specimen should be taken from the vicinity of the tensile or impact specimen or the clamping section of the tensile or impact specimen far from the notched end. The sampling quantity for metallographic inspection should comply with the provisions of the purchase contract or forging procurement specification.

The base material of manganese nickel molybdenum steel forgings is shown in the certificate

The tube plate forging should be equipped with a base material certificate. The witness piece should be taken from the remaining material of the test material used for the acceptance test of the forging or from the extended section of the forging. Records of the identification, orientation, size, and relative position to the acceptance test material should be made.

Nondestructive testing of manganese nickel molybdenum steel forgings

Visual inspection

At each stage of manufacturing and machining, a visual inspection of the surface of forgings should be carried out by NB/T 20003.7-2010.

The forging surface should be free of visible cracks, interlayers, folds, slag inclusions, or other harmful defects.

If any unqualified defects are found in the forgings through visual inspection after final machining, the provisions of Chapter 10 of this part shall be followed.

Penetrant or magnetic particle inspection

After final machining, magnetic particle testing can be performed on all surfaces, and penetrant testing can also be used as a substitute for magnetic particle testing. The requirements and acceptance standards for penetrant testing and magnetic particle testing shall be by NB/T 20328.4-2015, and NB/T 20328.5-2015, respectively, and cracks are not allowed. When there are provisions in the order contract or forging procurement specification, they can be executed according to the provisions in the order contract or forging procurement specification.

If any unqualified defects are found on the forging according to the above inspection methods for forgings, the provisions of Chapter 10 of this part shall be followed.

Ultrasonic Testing

Testing timing

Testing should be carried out after the final machining of the forging. For areas that are difficult to detect after the final machining, testing should be carried out in advance as close to the final delivery state as possible.

Testing methods

Ultrasonic testing should be carried out by the provisions of NB/T 20003.2-2010, using direct beam testing and oblique beam testing.

The characteristic parameters of the probe are usually as follows:

Direct beam detection: The probe frequency is 4MHz or 2MHz, depending on the forging structure;

Oblique beam detection: The probe frequency is 2MHz or 1MHz, depending on the forging structure, and the refractive angle is 45 °.

Scanning method and detection scope

Implement testing according to the specified scope for Type II forgings in NB/T 20003.2-2010.

Scan according to Figure E.2 in Appendix E of NB/T 20003.2-2010.

Signal evaluation

Evaluate defect signals according to NB/T 20003.2-2010.

Record conditions and acceptance criteria

Direct beam detection should meet the quality level II requirements in Table 14 of NB/T 20003.2-2010.

Oblique beam detection should meet the requirements of 14.7 and 14.8.1 in NB/T 20003.2-2010.

Removal and Repair of Defects in Steel Forgings

The forging defects can only be accepted if the size is within the tolerance range after grinding removal.

After the forging is polished, magnetic particle testing should be carried out on the polished parts by the provisions of NB/T 20328.5-2015. The acceptance standards for magnetic particle testing should be carried out by the provisions of NB/T 20328.5-2015.

Forging manufacturers are not allowed to weld and repair forgings.

Dimensional inspection of steel forgings

Dimensional inspection should meet the following requirements:

• Dimensional inspection should be conducted after heat treatment and before delivery;
• Dimensional inspection should be carried out according to the requirements of the order drawing, and the main dimensions should be recorded; The measured values should be within the tolerance range specified in the order drawing.

Marking of manganese nickel molybdenum steel forgings

The logo should meet the following requirements:

• The forging manufacturer shall determine the identification marks and marking methods used by the provisions of the contract;
• The witness parts of the base material shall be marked according to the provisions of the contract;
• The mark should be placed in a prominent position on the forging, and the position and method of the mark should be non-destructive to the final use of the forging.

Cleaning, Packaging, and Transportation of Steel Forgings

The contract’s provisions shall carry out cleaning, packaging, and transportation.

Quality certification documents for steel forgings

The forging manufacturer shall provide quality certification documents upon delivery, including at least the following:

• Chemical composition reports for melting analysis and finished product analysis;
• Heat treatment report (including possible re-heat treatment);
• Mechanical performance test report;
• Metallographic inspection report;
• Non-destructive testing report;
• Dimensional inspection report.

The above test report should include the following content:

• Material grade, furnace number, batch number, and forging name and number;
• The identification mark of the forging manufacturer;
• Contract number;
• Name of testing and acceptance agency;
• The results of each experiment and retest, as well as the corresponding specified values.

Appendix A

(Normative Appendix)
Schematic diagram of the cutting position of the test material for tube plate forgings

Figure.A.1 Schematic diagram of the cutting position of the tube plate test material

Appendix B

(Normative Appendix)
Supplementary testing

B.1. Determination of RT_NDT temperature

B.1.1 Testing
Determine RT_NDT temperature through drop hammer test and Charpy V-notch impact test.
The drop hammer test shall be carried out in accordance with the provisions of NB/T 20004-2014. P-3 type specimens shall be used for the drop hammer test to determine the forging material’s nonplastic transition temperature (T_NDT).
The Charpy V-notch impact test is conducted according to the T_NDT temperature to determine the temperature of the Charpy V-notch impact test. The test is carried out in accordance with the provisions of NB/T 20004-2011 to determine the RT_NDT temperature.
The sample for the drop hammer test should be taken at least 20mm from any quenched surface and at least 40mm from other surfaces.
The impact test specimen should have its centerline at least 50mm away from the flat end face of the test ring and at least 100mm away from the inner circular surface.
The shape, size, and testing method of the drop hammer test specimen shall be in accordance with the provisions of NB/T 20004-2011.
The shape, size, and testing method of the impact test specimen shall be in accordance with the provisions of NB/T 20004-2011.
The number of tests, sampling direction, and test temperature are listed in Table D.1.
The bottom line of the impact specimen notch should be perpendicular to the upper and lower surfaces of the forging.
Each group of impact tests should have three specimens. The fiber cross-sectional area and lateral expansion value should be provided as data, and the measurement method should be carried out in accordance with the provisions of NB/T 20004-2014.
Table.A.1 Supplementary Tests

Test Items	Sample status	Sampling Direction	Test temperature ° C	Number of setsb	Number of samples per set
Drop Hammer Test	HTMP+SSRHT	Radial	a	2	8
Impact Test	HTMP+SSRHT	Circumferential	a	2	12
Note 1: HTMP – Performance heat treatment; SSRHT – Simulated stress relief heat treatment.
a The test temperature should be carried out in accordance with the provisions of NB/T 20004-2011
b When two sets of test specimens are required, one set should be taken from each specimen.

B.1.2 Acceptance criteria
The RT_NDT temperature should not exceed -20 ℃.

B.2 Determination of impact energy value on platform 2

B.2.1 Testing

This energy value is measured through a series of samples. In addition to the following requirements,
The sampling and testing conditions for this experiment are the same as above:

• 1) The sample state is HTMP+SSRHT state;
• 2) The direction of the sample is circumferential;
• 3) The axis of the specimen notch is parallel to the component’s surface.

B.2.2 Acceptance criteria

The fracture energy value must be greater than or equal to 130J.

Source: China Forgings Manufacturer – Yaang Pipe Industry (www.epowermetals.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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