Can you explain to me the difference between AMS-H-7199 and AMS 2728 when it comes to heat treating copper-beryllium alloy parts?
Your question is a good one. Both specifications are current and available through SAE International (www.sae.org). They are recognized by the Nonferrous Alloy Committee (AMS D) responsible for these Aerospace Material Specifications. While both specifications are very similar, there are subtle yet important differences. Specifically:
A.) AMS 2728A (Heat Treatment of Wrought Copper-Beryllium Alloy Parts) establishes the requirements for heat treatment of wrought copper-beryllium parts by users or by their vendors or subcontractors. It is essentially a REWRITE and an update/expansion of AMS-H-7199. Here are a few examples of what the specification includes:
1. AMS 2728A makes reference to more recent AMS and ASTM specifications - for example AMS 2750 (Pyrometry) and ASTM E 3 (Preparation of Metallographic Specimens).
2. AMS 2728A adopts the Unified Numbering System (UNS) designations for materials.
3. AMS 2728A uses current temper designations. By way of example, TX00 (A), TX01 (1/4H), TX02 (1/2H), TX03 (3/4H), and TX04 (H). Here "X" can be "B" or "D" if the temper is before precipitation hardening or "F" or "H" if after precipitation hardening. The numbers in parentheses are the old temper designations (used in AMS-H-7199) and include "A" for fully annealed, "1/4H" refers to 1/4 hard and so forth.
4. AMS 2728A includes requirements for statistical sampling as part of inspection, logs (written and electronic) and report/calibration records.
B.) AMS-H-7199 (Heat Treatment of Wrought Copper-Beryllium Alloys, Process For (Copper Alloys: Numbers C17000, C17200, C17300, C17500, and C17510) presents requirements for the heat treatment of parts and components fabricated from wrought (plate, sheet, strip, bar, rod, wire extrusions and tube and forgings) copper alloys, specifically numbers C17000, C17200, C17300, C17500 and C17510) and is a REISSUE of an older U.S. government military standard, MIL-H-7199. It is still in force for a number of reasons including the needs of reverse-engineering projects. Also, the specification contains specific information on certain aspects of heat treating referred to in a more general sense by AMS 2728A. Here are a few examples:
1. AMS-H-7199 talks specifically about "bright-hardening" requirements.
2. AMS-H-7199 addresses issues related to inspection of equipment.
3. AMS-H-7199 talks about process control (in a different way than AMS 2728A).
4. AMS-H-7199 includes cross reference to older copper-alloy designations - for example Alloy 171 = C17000 (UNS C17000); Alloy 172 = C17200 (UNS C17200) or C17300 (UNS C17300) and Alloy 175 = C17500 (UNS C17500) or C17510 (UNS C17510)
Heat Treatment of Copper-Beryllium Alloys
Dan Herring is president of THE HERRING GROUP Inc., which specializes in consulting services (heat treatment and metallurgy) and technical services (industrial education/training and process/equipment assistance). He is also a research associate professor at the Illinois Institute of Technology/Thermal Processing Technology Center. tel: 630-834-3017; e-mail: email@example.com; web: www.heat-treat-doctor.com
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