March 03,2023

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 - 1925_oF, for 2 hours minimum, oil Quenched or air cooled to room temperature, then tempered at 1250_oF minimum.
• Stress Relief - Subsequent to any straightening operations, a stress relieving heat treatment at 1100_oF 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).

NUMBER OF TESTS

• 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.

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:

• 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.