Rotor Forgings for 50 MW to 200 MW Turbine Generators — Technical Specification
1 Scope
This standard specifies the order requirements, manufacturing process, technical specifications, inspection rules, test methods, acceptance and quality certificate, marking and packaging of vacuum-treated alloy steel forgings for rotors for 50 MW to 200 MW turbine generators.
This standard is applicable to the order, manufacturing and inspection of vacuum-treated alloy steel forgings for rotors for 50 MW to 200 MW turbine generators.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 223 (all parts) Methods for Chemical Analysis of Iron, Steel and Alloy
GB/T 228.1 Metallic Materials — Tensile Testing — Part 1: Method of Test at Room Temperature
GB/T 229 Metallic Materials — Charpy Pendulum Impact Test Method
GB/T 231.1 Metallic Materials — Brinell Hardness Test — Part 1: Test Method
GB/T 4336 Standard Test Method for Spark Discharge Atomic Emission Spectrometric Analysis of Carbon and Low - Alloy Steel (Routine Method)
GB/T 6394 Determination of Estimating the Average Grain Size of Metal
JB/T 1581 Ultrasonic Testing Method for Rotor and Shaft Forgings of Steam Turbines and Turbine Generators
JB/T 8468 Magnetic Particle Testing for Steel Forgings
JB/T 8888 Test Method for Measuring Residual Stresses by the Ring-core Method in Rotor Forgings for Turbine and Generator
ASTM A 341/A 341 M Standard Test Method for Direct Current Magnetic Properties of Materials Using D-C Permeameters and the Ballistic Test Methods
ASTM A 370 Standard Test Methods and Definitions for Mechanical Testing of Steel Products
3 Order Requirements
3.1 The purchaser shall indicate the reference standard, forging grade, material designation, corresponding technical specifications and inspection items, as well as other additional information in the order contract or technical agreement.
On the drawing, forging grade and material designation shall be marked as follows:
Steel designation
Forging grade × No. of this standard
3.2 The purchaser shall provide the order drawing of forgings with marked sampling position for mechanical properties test and rough machining size, and if necessary, the finishing size shall be indicated.
4 Manufacturing process
4.1 Smelting and pouring
4.1.1 Steel used for forgings shall be smelted in basic electric furnace. As agreed by the purchaser, other smelting methods ensuring the quality may also be adopted.
4.1.2 Before or during ingot casting, molten steel shall be degassed by vacuum. Generally, in the process of vacuum treatment, the ultimate pressure of the vacuum system shall be less than 133Pa.
4.2 Forging
4.2.1 The upper and lower ends of steel ingot shall have adequate cut-off quantity so as to ensure that the forging is free from shrinkage cavity and excessive segregation.
4.2.2 Forgings shall be forged on a forging press with sufficient capacity so that the whole section of the forgings can be thoroughly forged. Maintain the superposition of the axle of forgings and the axial direction centerline of steel ingots as possible. The better quality end of the ingot shall be used as the forgings for turbine end.
4.3 Fillet
At each manufacturing stage, the corresponding fillet shall be retained at the step transitions where the diameter of the forgings changes.
4.4 Heat treatment
Foreword I
1 Scope
2 Normative References
3 Order Requirements
4 Manufacturing process
4.1 Smelting and pouring
4.2 Forging
4.3 Fillet
4.4 Heat treatment
4.5 Machining
5 Technical Specifications
5.1 Chemical compositions
5.2 Mechanical property
5.3 Residual stress
5.5 Grain size
5.6 Hardness
5.7 Non-destructive testing
5.8 Dimensions, tolerances and surface roughness
6 Inspection Rules and Test Methods
6.1 Chemical composition analysis
6.2 Mechanical properties test
6.3 Residual stress determination
6.4 Determination of magnetic property
6.5 Determination of grain size
6.6 Hardness inspection
6.7 Non-destructive testing
6.8 Retest and re-heat treatment
7 Acceptance and Quality Certificate
8 Marking and Packaging
Table 1 Chemical compositions
Table 2 Permissible deviation of chemical composition of finished products
Table 3 Mechanical properties
Table 4 Equivalent diameter and number of single and dispersed defects
