UNS S15700 (PH15-7Mo®, AISI 632) stainless steel for aircraft components requiring high strength at elevated temperature

1 PRODUCT

UNS S15700 (PH15-7Mo®, AISI 632) stainless steel for aircraft components requiring high strength at elevated temperatures.

UNS S15700 is available in product forms as plate, sheet, strip, pipe, tube, bar (round, flat, hexagon, square, shapes), wire (profile, round, flat, square), forgings, etc.

2 EQUIVALENT DESIGNATION

Type 632(ASTM), 0Cr15Ni7Mo2Al (GB/T), SUS 632(JIS), ATI 15-7™, PH15-7Mo®

3 APPLICATION

S15700 is mainly used for applications requiring high strength and a moderate level of corrosion resistance.

S15700 is particularly beneficial for a wide range of applications that include retaining rings, springs, diaphragms, aircraft bulkheads, welded and brazed honeycomb paneling and other aircraft components requiring high strength at elevated temperatures.

4 OVERVIEW

S15700 stainless steel is a chromium-nickel-molybdenum-aluminum semi-austenitic, precipitation-hardening stainless steel that provides high strength and hardness, good corrosion resistance and minimum distortion on heat treatment.

The S15700 alloy is similar to S17700 precipitation hardening SS. S15700 is designed with substitution of approximately 2.0 percent molybdenum for 2.0 percent chromium in the S17700. This results in somewhat higher room and elevated temperature strength for the S15700.

S15700 is easily formed in the annealed condition and develops an effective balance of properties by simple heat treatments.

For applications requiring exceptionally high strength, S15700 stainless steel in Condition CH 900 is particularly useful for applications with limited ductility and workability.

In its heat-treated condition, this alloy provides excellent mechanical properties at temperatures up to 900 °F (482 °C). Its corrosion resistance is superior to that of the hardenable chromium types.

In some environments, corrosion resistance approximates that of the austenitic chromium-nickel stainless steels. Fabricating practices recommended for other chromium-nickel stainless steels can be used for S15700 stainless steel.

5 CHEMICAL COMPOSITION (wt%):

6 PHYSICAL PROPERTY

7 MECHANICAL PROPERTIES

Typical room temperature mechanical properties

8 CORROSION RESISTANCE

The general level of corrosion resistance of S15700 stainless steel in Conditions TH 1050 and RH 950 is superior to standard hardenable types of stainless such as Types 410, 420 and 431, but is not quite as good as Type 304.

Corrosion resistance and compatibility in Rocket fuels

Oxygen – While oxygen is highly reactive chemically, liquid oxygen is noncorrosive to most metals. The precipitation hardening stainless steels experience no problem.

Ammonia –S15700 stainless steel is satisfactory for handling ammonia.

Hydrogen – Liquid hydrogen and gaseous hydrogen at low temperatures are noncorrosive.

Nitrogen Tetroxide – Static tests in nitrogen tetroxide containing 3.2% by weight water lasting from 3 to 27 days, S15700 stainless steel, Condition RH 950, has shown very low corrosion rates up to 165°F (74°C). Under circulating conditions at 79°F (26°C) to 88°F (31°C) for 100 hours, it has shown no corrosion.

9 HEAT TREATMENT

S15700 stainless steel requires three essential steps in heat treating:

1) Austenite conditioning

2) Cooling to transform the austenite to martensite

3) Precipitation hardening

Standard heat treatments

It presents the procedures for heat treating material in condition A to conditions TH 1050 and RH 950.

Condition A

For in-process annealing (mill annealing), the alloy should be heated to 1950 ± 25°F (1066 ± 14°C) for three minutes for each 0.1 in. (2.5 mm) of thickness, and air cooled. This treatment may be required to restore the ductility of cold-worked material so that it can take additional drawing or forming. Although most formed or drawn parts do not require

re-annealing prior to hardening, annealing is required on severely formed or drawn parts to be heat treated to Condition TH 1050 if full response to heat treatment is required. Annealing is unnecessary in the case of the RH 950 heat treatment.

Procedure from condition A to conditions TH 1050

Procedure from condition A to conditions RH 950

Procedure from condition A to conditions CH 900

10 FORMABILITY

S15700 stainless steel in Condition A can be formed comparably to Type 301. It work hardens rapidly, and may require intermediate annealing in deep drawing or in forming intricate parts. Springback is similar to that of Type 301.

This alloy is extremely hard and strong in Condition C. Therefore, fabrication techniques for such materials must be used.

11 STANDARD SPECIFICATION

AMS 5520 Sheet, Strip and Plate

AMS 5657 Bars and forgings

AMS 5812 Welding wire

AMS 5813 Welding wire

ASTM A461 Bars, Forgings and Forging Stock

ASTM A564 / ASTM SA564 Bars, wire and shapes

ASTM A579 Forings

ASTM A693 / ASME SA693 Sheet, Plate and Strip

ASTM A705 / ASME SA705 Age hardening stainless steel forgings

MIL S-8955 Plate, Sheet and Strip

12 COMPETITIVE ADVANTAGE

(1) More than 50 years experience of research and develop in high temperature alloy, corrosion resistance alloy, precision alloy, refractory alloy, rare metal and precious metal material and products.
(2) 6 state key laboratories and calibration center.
(3) Patented technologies.

(4) Ultra-purity smelting process: VIM + IG-ESR + VAR

(5) Excellent high performance.

13 BUSINESS TERM

With background of more than 50 years of material R&D experience, CMMC is a high-tech enterprise specialized in production of high temperature alloys, corrosion resistant alloys, precision alloys, wear resistant alloys, refractory alloys and other special alloys.

With main smelting equipments by CONSARC, including vacuum induction melting furnace (VIM 3 metric tons x 1 set), inert gas protective electric slag remelting furnace (IG-ESR 5 metric tons x 1 set, 10 metric tons x 2 sets), vacuum arc remelting furnace (VAR 10 metric tons x 1 set), CMMC has an annual production capacity of 3000 metric tons.

Established in 2016, CMMC stll having an investing plan of more than 30 million U.S.Dollars in the coming 5 years. CMMC aspires to become an internationally renowned supplier and leading brand of key materials for core components of high-end equipments in the application fields of aerospace, clean energy, petroleum, chemical engineering, medical, marine engineering, food and automobile, etc.

Our main products include forgings, bars, rods, tubulars, plates, sheets, strips, wire rods, precision wires, etc.

From ultra-pure smelting,  hot and cold forming, heat treatment, mechanical processing to finish machining, CMMC provides the whole process of one-stop professional services.

From demand idea to research and development, from technology innovation to promoting of products upgrading, from customer's puzzles and difficulties to final solution, from smelting to market, no matter wherever, whenever, whatever and however, CMMC always try to provide satisfactory one-stop service.

By providing better materials to make a better world, CMMC never give up the dream.