This specification identifies hot rolled, heat treated and descaled 12% Chromium, UNS S42200 martensitic stainless steel bars, for steam turbine bucket and blade applications at elevated temperatures.Unless otherwise specified, all requirements of ASTM A 565 shall apply.
ASTM Standards: A 565, Martensitic Stainless and Heat-Resisting Steel Bars and shapes
CHEMICAL COMPOSITION
Heat Analysis- Each heat of steel shall meet the Requirements of ASTM A 565, UNS S42200 as modified in Table 1.
MECHANICAL PROPERTIES
Requirements - Mechanical properties at room temperature shall meet of ASTM A 565, UNS S42200, Condition HT
- Tensile Strength, psi, min. 120,000
- Yield Strength, psi, min. (0.02%) 85,000
- Elongation in 2 in., %, min. 15
- Reduction of Area, % min. 35
- Charpy V-Notch Impact, ft-lb, R min. 15
- Brinell Hardness, max. 285
MANUFACTURE
- Melting Process- Unless the electroslag re-melting (ESR) process is specified on the purchase order, the steel shall be made by the electric furnace process with or without separate refining, such as argon oxygen decarburization (AOD).
- Heat treatment - Bars shall be heated to 1875 - 1925oF, for 2 hours minimum, oil Quenched or air cooled to room temperature, then tempered at 1250oF minimum.
- Stress Relief - Subsequent to any straightening operations, a stress relieving heat treatment at 1100oF minimum is required.
- Finish - All bars shall be furnished in the hot rolled and descaled condition.
MICROSTRUCTURE
Delta Ferrite - Delta Ferrite shall be limited to 5 % of the microstructure.
QUALITY REQUIREMENTS
- Bar Quality - Bars purchased under this specification are intended to be of the best quality with internal soundness and uniform metallurgical structure and properties.
- Vendor is subject to the requirements of TSP-06-03 (TurboCare Approval and Control of Vendors).
- Hardness - Hardness test shall be taken on 10% of the bars in a lot.
- Tension - Two tension tests shalll be randomly selected and tested from each lot. Hardness values of the tension test specimens shall be reported with the tensile data.
- Impact- Two impact tests shall be taken on the same bars selected for the tension test.
- Purchase order number;
- Purchaser's specification number;
- Heat number;
- Chemical heat analysis;
- Mechanical properties including tensile, impact and hardness test results;
- Heat treatment and stress relief, if any, temperatures and times;
- Statement that the material has been manufactured, sampled, tested and inspected in accordance with this specification and the results satisfied the requirements.
NUMBER OF TESTS
CERTIFICATION
Test Report - All tests required by this specification shall be made by the manufacturer and reported on a certificate of test to the purchaser. Each test certificate shall include the following data: