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Heat Treatment Standards Reference: ASM, SAE, AMS, MIL-H, ASTM, ASME

Heat treatment drawings and purchase orders reference a recurring set of standards — ASM Handbook volumes for process fundamentals, AMS and MIL specifications for process control, ASTM methods for verification, SAE documents for material properties and hardenability, and ASME/AWS/API codes for post-weld heat treatment on welded structures. UTEC Industrial provides in-house induction hardening, through-hardening, and quench-and-temper heat treating services for industrial components in the Pacific Northwest, with integrated CNC machining and reverse-engineering capability. Each standard has a specific scope: some are umbrella process specifications, some are test methods, some are code-driven requirements. This reference article catalogs the standards a buyer is most likely to see on an industrial heat treatment drawing, what each one covers, and when it applies — serving as the lookup companion to the how-to-specify and hardness-tolerance articles in this section.

What do the ASM Handbook Volume 4 series cover and when are they cited?​

The ASM Handbook Volume 4 series is the primary technical reference for heat treatment and is cited throughout industrial specifications whenever a process fundamental, transformation diagram, or material-specific cycle parameter needs a credible source. Volume 4A covers steel heat treating fundamentals and processes — annealing, normalizing, stress relieving, through-hardening, quench media, and tempering physics — and is the volume most heavily cited in production specifications for wrought steels (ASM Handbook, Vol. 4A, ASM International, 2013). Volume 4B covers steel heat treating technologies — furnace types, atmospheres, fluidized bed, induction, vacuum, and plasma — and is the reference for equipment and process-family discussions (ASM Handbook, Vol. 4B, ASM International, 2014). Volume 4C is the authoritative volume on induction heating and heat treatment, covering coil design, frequency selection, case depth prediction, and application case histories; any induction hardening specification beyond a basic hardness callout benefits from citing Volume 4C for the underlying physics (ASM Handbook, Vol. 4C, ASM International, 2014). Volume 4D covers heat treatment of irons and steels with per-grade detail, and Volume 4E covers nonferrous alloys including the aluminum solution-plus-age cycles. These are handbooks, not enforceable standards — they provide the technical basis that specifications build on, and they are the default citation when a drawing note or documentation package needs to reference "industry-standard practice."

What is MIL-H-6875 and when is it still applicable?​

MIL-H-6875 (Heat Treatment of Steel, Process For) is a US Department of Defense specification for heat treatment of steel parts, originally issued to govern military and defense-contract work and still referenced on many legacy drawings in aerospace, defense, and heavy-industrial sectors (MIL-H-6875H). Its scope covers austenitizing temperatures, quench media, tempering requirements, straightening, cleaning, and documentation — essentially a full process-specification envelope for steel heat treatment. The document has been partially superseded by the AMS 2759 family (see below) for aerospace work, and many commercial programs have migrated from MIL-H-6875 to AMS 2759 or to internal process specifications. However, MIL-H-6875 is still cited on active drawings for defense work, on spare-parts manufacturing for legacy platforms, and on some heavy industrial components where the originating engineer chose the military specification as the process reference. When a drawing references MIL-H-6875, the buyer should confirm with the heat treater that the current revision and the required class of processing can be supported; if the drawing specification lists a Nadcap or aerospace pyrometry requirement in addition to MIL-H-6875, that typically indicates the job belongs at a Nadcap-accredited aerospace heat treater rather than a general-industrial shop.

What is the AMS 2759 family and how are its sub-specs organized?​

AMS 2759 is the SAE Aerospace umbrella specification for heat treatment of steel parts; its sub-specifications divide the work by material class and strength range, with each sub-spec defining the allowable austenitizing temperatures, quench parameters, tempering requirements, and verification methods for that class (AMS 2759). AMS 2759/1 covers heat treatment of carbon and low-alloy steel parts with minimum tensile strength below 220 ksi — the sub-spec most commonly cited on general aerospace steel parts (AMS 2759/1). AMS 2759/2 covers low-alloy steel at 220 ksi and above — the high-strength regime with tighter process controls (AMS 2759/2). AMS 2759/3 covers precipitation-hardening corrosion-resistant and maraging steels, AMS 2759/4 covers austenitic corrosion-resistant steel solution annealing, and additional sub-specs cover carburizing, nitriding, induction hardening, and other process families. The 2759 family is the aerospace-grade process specification — it is stricter than general-industrial practice in its pyrometry, documentation, and recordkeeping requirements, and compliance is usually audited through Nadcap. Buyers who see AMS 2759/X on a drawing should expect the work to be routed to a Nadcap-accredited heat treater; specifying AMS 2759 on commercial industrial parts adds cost and lead time without a corresponding function benefit, and is a common specification mistake on non-aerospace work.

What is AMS 2750 and what does the Class 1–5 structure mean?​

AMS 2750 (Pyrometry) is the SAE Aerospace standard governing furnace temperature uniformity, instrument accuracy, thermocouple calibration, and process recording for heat-treating equipment — the pyrometry framework that AMS 2759 and other aerospace specifications build on (AMS 2750). The standard defines furnace classes 1 through 5 based on temperature-uniformity requirements across the working zone, with Class 1 the tightest (typically ±5 °F across the qualified work zone) and Class 5 the loosest (typically ±25 °F). Class determines the temperature uniformity survey (TUS) cadence, the number of thermocouples required during surveys, and the instrument calibration tolerance. Higher-class furnaces require more frequent TUS, tighter calibration of control and recording instruments, and more extensive documentation of every cycle. AMS 2750 also establishes the system accuracy test (SAT) for verifying the control loop, the work thermocouple-to-load thermocouple correlation practice, and the expiration of surveys and calibrations. Buyers with AMS 2750 Class 1 or Class 2 requirements on their drawings should confirm directly with their heat treater that the shop holds the required pyrometry class on the specific furnace that will run the job — general-industrial heat treaters typically survey to Class 3, 4, or 5 cadence if pyrometry is tracked at all, and the stricter Class 1/2 regime generally belongs at Nadcap-accredited aerospace heat treaters.

What do SAE J1397, J403, and J1249 cover and when should they be referenced?​

SAE J1397 (Estimated Mechanical Properties and Machinability of Steel Bars) is the published reference for typical mechanical properties — tensile strength, yield, elongation, reduction of area, Brinell hardness — of common steel grades in various heat-treated conditions, by bar diameter and by temper (SAE J1397). It is the first document a design engineer should consult when deciding whether a specific grade at a specific heat treat condition will meet a mechanical property target, and it is a citable source on drawings that require both a grade and a property callout ("4140 per ASTM A29, quench and temper to 28–34 HRC / 135 ksi min yield per SAE J1397 typical"). SAE J403 (Chemical Compositions of SAE Carbon Steels) is the chemistry specification for carbon steels — the grade-composition table referenced when a drawing calls out "1045 per SAE J403"; the alloy-steel equivalent compositions are in SAE J404 (Chemical Compositions of SAE Alloy Steels). SAE J1249 (Former SAE Standard and Former SAE Ex-Steels) is the grade-designation cross-reference for legacy and superseded grade numbers, useful when an old drawing references a grade number that has been re-designated or combined with another. For hardenability, SAE J406 (Methods of Determining Hardenability of Steels) and SAE J1268 (Hardenability Bands for Carbon and Alloy H Steels) are the pair — J406 defines the test procedure and J1268 publishes the bands for each H-designated grade. A drawing specifying "4140H per SAE J1268" is asking for material meeting the published hardenability band, which is stricter than nominal 4140.

What is ASTM A255 and how does it relate to the Jominy end-quench test?​

ASTM A255 (Standard Test Methods for Determining Hardenability of Steel) is the US-standard test procedure for the Jominy end-quench test — the single most widely used hardenability measurement for steel (ASTM A255). The test machines a standard 1.0-inch-diameter by 4.0-inch-long specimen from the steel in question, austenitizes it, and quenches one end with a standardized water spray while the rest cools by radiation and conduction. Hardness is then measured along the length of the bar at specified distances from the quenched end, producing a hardness-vs-distance curve that characterizes the steel's response to cooling rate. The curve maps directly to the hardenability band data published in SAE J1268 for H-designated grades, and it lets a designer predict the hardness at any depth in a part being quenched in a given medium. ASTM A255 specifies the specimen preparation, austenitizing parameters, the quench fixture geometry, the hardness measurement spacing, and the reporting format. The parallel international standard is ISO 642; the SAE equivalent procedure is SAE J406. A drawing or material specification that calls out "hardenability per ASTM A255" or "H-band per SAE J1268" is asking the mill or the heat treater to verify that the steel falls within the published band, typically by running a Jominy on a bar from the production heat.

What do ASTM E18, E10, and E140 cover for hardness verification?​

ASTM E18 (Standard Test Methods for Rockwell Hardness of Metallic Materials) is the Rockwell hardness standard — it defines the indenter geometries, test loads, dwell times, specimen preparation, and acceptance criteria for all Rockwell scales including HRC, HRB, HRA, and the superficial scales (15N, 30N, 45N) used for thin sections and hardened surfaces (ASTM E18). A hardness callout of "50–55 HRC per ASTM E18" on a drawing tells the inspector exactly which scale, indenter, and load to use and sets the procedural basis for any dispute about the result. ASTM E10 (Standard Test Method for Brinell Hardness of Metallic Materials) is the corresponding Brinell standard, specifying the 10 mm tungsten carbide ball, 3,000 kgf load, 10–15 second dwell, and optical measurement of indentation diameter used to compute HB — the method of choice for softer or larger parts (ASTM E10). ASTM E140 (Standard Hardness Conversion Tables for Metals) provides the empirical conversions between HRC, HB, HV, HRA, and the superficial scales for steel in common hardness ranges; conversions are approximate, and E140 is the reference when a drawing specifies hardness in one scale but inspection is performed in another (ASTM E140). Related standards in the same family include ASTM E92 for Vickers and Knoop hardness, ASTM E384 for microindentation hardness used in case depth profiling, and ASTM E110 for portable (UCI and Leeb) hardness testing.

What is ASTM A370 and when is it the governing test-method document?​

ASTM A370 (Standard Test Methods and Definitions for Mechanical Testing of Steel Products) is the umbrella document for mechanical property testing of steel — tensile, bend, impact, hardness, and related tests, with definitions of terms and annexed procedures specific to different product forms (ASTM A370). On heat-treated parts, A370 is the citable reference for how the mechanical property verification is to be performed when the drawing requires mechanical property acceptance in addition to hardness — for example, a pressure-vessel forging with a minimum tensile, yield, and elongation specification after quench and temper. The standard defines tensile specimen geometry for different product forms, bend test radii, Charpy impact test specimen and temperature requirements, and the acceptance structures for each. A370 is frequently invoked on heat treatment documentation packages as the method of record when the customer requires more than a hardness test — UTEC's heat treatment records are structured to meet ASTM A370 reporting and AMS 2750 pyrometry furnace-chart expectations where applicable, with hardness, cycle parameters, and equipment identification on every job and mechanical test data added where the drawing calls for it. Buyers should check A370 specifically when their drawings call for mechanical property verification from a heat-treated part, since the specimen location, orientation, and count requirements affect cost and lead time.

How does ASME Boiler and Pressure Vessel Code Section VIII Div 1 govern PWHT?​

ASME Section VIII Division 1 is the construction code for unfired pressure vessels, and paragraph UCS-56 with its associated tables is the section that governs post-weld heat treatment (PWHT) of carbon and low-alloy steel vessels (ASME Section VIII Div 1, UCS-56). The tables in UCS-56 organize steels by P-Number group (P-No. 1 carbon steels, P-No. 3 and P-No. 4 low-alloy, P-No. 5A and 5B chromium-molybdenum, and so on), and for each group specify the minimum holding temperature, the minimum holding time by nominal thickness, heating-rate and cooling-rate limits, and any exemption conditions under which PWHT may be omitted. For a typical carbon steel P-No. 1 vessel above the exemption thickness, the rule is a minimum holding temperature of 1,100 °F and a minimum holding time of 1 hour per inch of thickness (with a 15-minute floor), heating and cooling rates controlled to 400 °F/hr maximum through the upper range, and the part above 800 °F placed in a furnace atmosphere that won't produce excessive scale or decarburization. Section VIII Division 2 (alternative rules) and Division 3 (high-pressure) have parallel but distinct PWHT requirements. The companion document is Section IX (Welding and Brazing Qualifications), which governs welding procedure qualification and welder performance, and which lists PWHT as an essential variable for many procedures — meaning a change in PWHT requires procedure requalification (ASME Section IX). A buyer ordering a code-stamped vessel will see UCS-56 cited on the fabrication documents and the PWHT chart from the heat treater becomes part of the code package.

What does AWS D1.1 Clause 7 (historically 5.8) specify for structural PWHT?​

AWS D1.1 (Structural Welding Code — Steel) governs welding of structural steel buildings, bridges, and industrial structures; the post-weld heat treatment requirements are in Clause 7 of recent editions of the code (historically Clause 5.8 in older editions frequently referenced on legacy drawings) (AWS D1.1). The clause specifies when PWHT is required, the holding temperatures and times for different base metal groups, the heating and cooling rate limits, and the documentation requirements. Unlike ASME Section VIII, PWHT is not required for most structural steel work under D1.1 — it is typically invoked only on specific heavy sections, high-restraint joints, or materials where the welding engineer has determined PWHT is needed to control residual stress or hydrogen. When PWHT is required, the D1.1 cycle is similar in form to the ASME cycle: minimum 1,100 °F holding temperature for carbon steels, 1 hour per inch of thickness, controlled ramp and cool. The bridge welding code AWS D1.5 has parallel requirements with additional provisions for the thicker plate used in bridge construction. Buyers who see "PWHT per AWS D1.1 Clause 7" on a structural drawing should confirm the specific material group, thickness, and any exemption conditions that apply to their part before committing to a heat treater and a cycle; the code language is not self-executing and requires interpretation against the specific fabrication.

What are API 510 and API 650, and when do they drive heat treatment work?​

API 510 (Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration) governs the in-service inspection, repair, and alteration of pressure vessels that were originally constructed to ASME Section VIII or equivalent codes (API 510). When a vessel is repaired by welding — for example, a corroded shell plate replaced, a nozzle re-welded, a weld defect excavated and re-welded — API 510 specifies when post-weld heat treatment of the repair is required. The default is that PWHT follows the original construction code (ASME Section VIII UCS-56 for a carbon steel vessel), but API 510 includes provisions for alternative repair methods such as controlled-deposition welding or temper-bead welding that can achieve equivalent properties without full PWHT in certain material classes — important for vessels that cannot practically be removed from service for a full furnace PWHT cycle. API 650 (Welded Tanks for Oil Storage) is the construction standard for welded atmospheric storage tanks and governs the welding and heat treatment requirements for new tank construction; its PWHT requirements are generally less prescriptive than ASME Section VIII because atmospheric tanks operate at much lower pressures, but specific provisions for thick-wall tanks, cold-climate service, and stress-relieved joints apply. Buyers in the oil and gas, chemical, and power industries will see API references on both new-construction and repair drawings; the practical implication for the heat treater is furnace capacity (large tanks and vessels can exceed typical furnace envelopes), ramp and soak control, and documentation that will become part of the vessel's jurisdictional inspection record.

What does a buyer typically need to check when a drawing cites an unfamiliar standard?​

Several checks resolve the majority of specification confusion when an unfamiliar standard appears on a drawing. First, identify what type of standard it is: an ASM Handbook reference is technical background (not an enforceable acceptance criterion); an AMS or MIL specification is a process specification that the heat treater must be qualified to run; an ASTM E-series standard is a test method; an ASME or AWS clause is a code requirement that generates formal documentation. Second, check whether the standard is current or superseded — MIL-H-6875, some AMS documents, and many older SAE standards have been revised or combined, and the drawing may cite a revision that has been updated. Third, match the standard's scope against the part: MIL-H-6875 and AMS 2759 are steel-parts standards and don't govern aluminum aging; AMS 2770 (Heat Treatment of Wrought Aluminum Alloy Parts) is the aluminum equivalent. Fourth, confirm the qualification requirements: if the standard implies Nadcap accreditation, the work belongs at a Nadcap-accredited heat treater; if the standard allows general-industrial processing with documentation, most competent heat treaters can run it. Fifth, evaluate cost-driver standards — AMS 2750 Class 1/2 pyrometry, full Nadcap routing, mechanical property test coupons per ASTM A370 — and confirm these are actually required by the function rather than copy-paste from an unrelated drawing template. A five-minute review of each standard cited against the actual service requirements often eliminates several unnecessary costs from the heat treatment budget and simplifies routing to the right vendor.

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References​

  • ASM International. (2013). ASM Handbook, Volume 4A: Steel Heat Treating Fundamentals and Processes. ASM International.
  • ASM International. (2014). ASM Handbook, Volume 4B: Steel Heat Treating Technologies. ASM International.
  • ASM International. (2014). ASM Handbook, Volume 4C: Induction Heating and Heat Treatment. ASM International.
  • ASM International. (2014). ASM Handbook, Volume 4D: Heat Treating of Irons and Steels. ASM International.
  • ASM International. (2016). ASM Handbook, Volume 4E: Heat Treating of Nonferrous Alloys. ASM International.
  • Heat Treater's Guide: Practices and Procedures for Irons and Steels (2nd ed.). (1995). ASM International.
  • Machinery's Handbook (31st ed.). (2020). Industrial Press.
  • AMS 2750: Pyrometry. SAE Aerospace.
  • AMS 2759: Heat Treatment of Steel Parts, General Requirements. SAE Aerospace.
  • AMS 2759/1: Heat Treatment of Carbon and Low-Alloy Steel Parts, Minimum Tensile Strength Below 220 ksi. SAE Aerospace.
  • AMS 2759/2: Heat Treatment of Low-Alloy Steel Parts, Minimum Tensile Strength 220 ksi and Higher. SAE Aerospace.
  • AMS 2759/3: Heat Treatment of Precipitation-Hardening Corrosion-Resistant and Maraging Steel Parts. SAE Aerospace.
  • AMS 2759/4: Heat Treatment of Austenitic Corrosion-Resistant Steel Parts. SAE Aerospace.
  • AMS 2770: Heat Treatment of Wrought Aluminum Alloy Parts. SAE Aerospace.
  • MIL-H-6875H: Heat Treatment of Steel, Process For. US Department of Defense.
  • ASME Boiler and Pressure Vessel Code, Section VIII Division 1 (UCS-56, current edition). American Society of Mechanical Engineers.
  • ASME Boiler and Pressure Vessel Code, Section IX (current edition). American Society of Mechanical Engineers.
  • AWS D1.1: Structural Welding Code — Steel (current edition, Clause 7). American Welding Society.
  • AWS D1.5: Bridge Welding Code (current edition). American Welding Society.
  • API 510: Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration (current edition). American Petroleum Institute.
  • API 650: Welded Tanks for Oil Storage (current edition). American Petroleum Institute.
  • ASTM A255: Standard Test Methods for Determining Hardenability of Steel. ASTM International.
  • ASTM A370: Standard Test Methods and Definitions for Mechanical Testing of Steel Products. ASTM International.
  • ASTM E18: Standard Test Methods for Rockwell Hardness of Metallic Materials. ASTM International.
  • ASTM E10: Standard Test Method for Brinell Hardness of Metallic Materials. ASTM International.
  • ASTM E92: Standard Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials. ASTM International.
  • ASTM E140: Standard Hardness Conversion Tables for Metals. ASTM International.
  • ASTM E384: Standard Test Method for Microindentation Hardness of Materials. ASTM International.
  • ASTM E110: Standard Test Method for Rockwell and Brinell Hardness of Metallic Materials by Portable Hardness Testers. ASTM International.
  • SAE J403: Chemical Compositions of SAE Carbon Steels. SAE International.
  • SAE J404: Chemical Compositions of SAE Alloy Steels. SAE International.
  • SAE J406: Methods of Determining Hardenability of Steels. SAE International.
  • SAE J1249: Former SAE Standard and Former SAE Ex-Steels. SAE International.
  • SAE J1268: Hardenability Bands for Carbon and Alloy H Steels. SAE International.
  • SAE J1397: Estimated Mechanical Properties and Machinability of Steel Bars. SAE International.

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