AM350, AM 350 and AM-350 Spelling Variations

The expressions AM350 stainless steel, AM 350 stainless steel and AM-350 stainless steel refer to the same alloy family. The difference is only a formatting or spelling variation.

Common references include:

• AM350 stainless steel
• AM 350 stainless steel
• AM-350 stainless steel
• AM 350 alloy
• AM350 alloy
• AM 350 PH stainless steel
• AM 350 semi-austenitic stainless steel
• AM 350 precipitation-hardening stainless steel
• Alloy 350 stainless steel
• Grade 350 stainless steel

Engineering documents should additionally state the required material specification, product form and heat-treatment condition. The designation alone does not define the final strength, hardness or microstructure.

UNS S35000, AISI 633 and Alloy 350 Designations

UNS S35000 is the Unified Numbering System designation commonly associated with AM 350 stainless steel. The alloy is also referenced as AISI 633 stainless steel, Type 633 stainless steel and Alloy 350 stainless steel.

Although these designations describe the same basic alloy family, individual specifications may establish different requirements for chemistry, dimensions, processing, testing, surface condition and mechanical properties.

Semi-Austenitic Stainless Steel Classification

AM 350 is classified as a semi-austenitic stainless steel because its microstructure changes during processing.

In the annealed condition, the alloy is largely austenitic. This condition provides better ductility and formability than the fully hardened condition. The austenitic structure is then destabilized through conditioning and transformed toward martensite by controlled cooling or sub-zero treatment.

A subsequent aging or tempering operation develops the required precipitation-hardening response. The final structure can contain tempered martensite, precipitation-strengthening phases, retained austenite and a controlled quantity of delta ferrite.

This transformation sequence differentiates AM 350 from conventional austenitic grades that are strengthened mainly through cold work and from martensitic grades that harden directly during conventional quenching.

Precipitation-Hardening Stainless Steel Classification

AM 350 PH stainless steel develops high mechanical strength through a combination of:

1. Austenite conditioning.
2. Martensitic transformation.
3. Sub-zero cooling where specified.
4. Precipitation hardening or aging.
5. Tempering at the selected temperature.

The resulting properties depend strongly on the complete heat-treatment route. Therefore, an AM 350 mechanical-properties statement should always identify whether the values apply to the annealed, SCT 850, SCT 1000, double-aged or another specified condition.

The precipitation-hardening response allows AM 350 stainless steel hardness and strength to be adjusted without relying exclusively on extensive cold deformation.

Chromium-Nickel-Molybdenum Alloy Description

AM 350 stainless steel is based on an iron-chromium-nickel-molybdenum system with controlled carbon and nitrogen.

Chromium supports passivation and general corrosion resistance. Nickel stabilizes the austenitic phase and contributes to toughness. Molybdenum improves resistance in several corrosive environments and strengthens the alloy. Carbon and nitrogen influence hardening response, precipitation behaviour, phase stability and final mechanical performance.

The controlled relationship between these elements enables AM 350 to remain formable in the annealed condition and develop a high-strength martensitic structure after conditioning and sub-zero treatment.

Applicable Standards and Specifications

AM 350 specifications can vary according to product form and application. Commonly referenced specifications include:

The applicable specification revision must be reviewed for exact composition limits, heat treatment, tensile requirements, hardness, tolerances, inspection and documentation.

UNS S35000 Designation

UNS S35000 stainless steel identifies the AM 350 alloy through the Unified Numbering System. The “S” prefix places the grade within the stainless and heat-resistant steel category.

The UNS number provides a consistent material identity, but it does not independently define:

• Product dimensions.
• Surface finish.
• Heat-treatment condition.
• Mechanical-property level.
• Inspection method.
• Dimensional tolerance.
• Certification requirement.

For this reason, a complete description may read UNS S35000 stainless steel in the SCT 850 condition or UNS S35000 sheet to ASTM A693 Type 633, depending on the engineering requirement.

AISI 633 Designation

AISI 633 stainless steel is another designation associated with AM 350. References to Grade 633 stainless steel, Type 633 stainless steel or Alloy 633 stainless steel should be reviewed together with the governing specification.

The AISI designation is useful for grade recognition, while ASTM, AMS or another application-specific specification defines the detailed material requirements.

ASTM A693 Type 633 Specification

ASTM A693 Type 633 is commonly associated with precipitation-hardening stainless steel sheet, plate and strip products corresponding to UNS S35000.

The specification may address:

• Chemical composition.
• Heat-treatment condition.
• Tensile properties.
• Hardness requirements.
• Product thickness.
• Flatness and dimensional tolerance.
• Surface quality.
• Test procedures.
• Retest and inspection provisions.

ASTM A693 Type 633 sheet and ASTM A693 Type 633 strip should be evaluated according to the required condition rather than by grade name alone.

AMS 5548 and AMS 5745 Product Specifications

AMS 5548 AM 350 and AMS 5745 AM 350 are commonly used aerospace-material references for specific product forms.

The exact scope can depend on the revision. Chemical composition, heat treatment, mechanical properties and acceptance requirements should therefore be checked against the applicable document.

Search descriptions such as AMS 5548 AM 350 strip, AMS 5745 AM 350 bar, AM 350 AMS 5548 properties and AM 350 AMS 5745 properties should always be interpreted in relation to the stated material condition.

Chemical Composition Table

The following table presents the nominal AM 350 chemical-composition limits supplied for the alloy.

Expanded AM 350 Chemical Composition

The iron content is normally determined by difference after accounting for the specified alloying and residual elements.

Functions of Chromium, Nickel, Molybdenum and Nitrogen

Chromium

Chromium forms the passive surface film responsible for stainless behaviour. The 16–17% chromium range supports AM 350 corrosion resistance and oxidation resistance.

Nickel

Nickel promotes austenite stability in the annealed condition. Its controlled level helps maintain formability while still allowing martensitic transformation after conditioning.

Molybdenum

Molybdenum contributes to strengthening and improves resistance in several localized or reducing corrosive environments. It also distinguishes AM 350 from several simpler chromium-nickel precipitation-hardening grades.

Nitrogen

Nitrogen contributes to strength, phase balance and precipitation behaviour. Its controlled content is important to the characteristic heat-treatment response of UNS S35000.

Carbon

Carbon participates in strengthening and precipitation reactions. Its level must be controlled because it also affects weldability, carbide formation and intergranular-corrosion behaviour.

Physical Properties Table

Physical properties can change slightly with heat treatment and microstructure.

Density, Specific Gravity and Melting Range

Electrical Resistivity

The following AM 350 electrical-resistivity values apply to material sub-zero cooled and tempered at 850°F / 454°C.

Mean Coefficient of Thermal Expansion

Values apply to sub-zero-cooled material tempered at 850°F / 454°C.

Thermal Conductivity

Values apply to AM 350 sub-zero cooled and tempered at 850°F / 454°C.

Modulus of Elasticity and Rigidity

Typical Poisson’s ratio values are approximately 0.27–0.30. The elastic modulus at room temperature is commonly reported in the approximate range of 190–210 GPa.

Mechanical Properties by Heat-Treatment Condition

AM 350 mechanical properties are controlled strongly by the selected heat-treatment condition.

Typical Room-Temperature Mechanical Properties

These are typical values rather than universal minimums. Actual acceptance values depend on product form, thickness, processing history and governing specification.

Tensile Strength

AM 350 tensile strength can remain relatively high even in the annealed condition, while precipitation-hardening treatments produce a major increase in yield strength and hardness.

Typical ultimate tensile-strength values include:

• Annealed: approximately 160 ksi or 1,103 MPa.
• SCT 1000: approximately 163 ksi or 1,124 MPa.
• Double aged: approximately 171 ksi or 1,179 MPa.
• SCT 850: approximately 198 ksi or 1,365 MPa.

SCT 850 provides the highest tensile strength among the listed conditions, while SCT 1000 provides a lower strength level with improved elongation and reduction of area.

Yield Strength

AM 350 yield strength changes significantly after martensitic transformation and precipitation hardening.

The annealed condition has a typical 0.2% yield strength of approximately 60 ksi or 414 MPa. After SCT 850 treatment, the typical yield strength rises to approximately 162 ksi or 1,117 MPa.

This large difference demonstrates why the heat-treatment condition must be stated in AM 350 engineering documentation. A single general value cannot accurately represent every AM 350 condition.

Elongation and Ductility

AM 350 elongation is highest in the annealed condition, where typical elongation can reach approximately 30%.

After hardening:

• SCT 850 typically provides approximately 15% elongation.
• SCT 1000 typically provides approximately 22% elongation.
• Double-aged material typically provides approximately 12% elongation.

SCT 1000 can be selected when a more balanced combination of strength, toughness and ductility is required. SCT 850 is more appropriate when maximum strength and hardness are the dominant considerations.

Hardness Details

AM 350 stainless steel hardness depends on the treatment sequence.

Hardness testing can be used as a practical process-control indicator, but hardness alone does not confirm complete compliance with tensile, microstructural or corrosion requirements.

Fatigue and Cyclic Fatigue Properties

AM 350 fatigue strength is one of the reasons the alloy is considered for bellows, diaphragms, springs and cyclically loaded valve components.

Fatigue behaviour is influenced by:

• Heat-treatment condition.
• Mean stress and stress amplitude.
• Surface finish.
• Grain direction.
• Section thickness.
• Forming strain.
• Weld geometry.
• Residual stress.
• Corrosive exposure.
• Operating temperature.
• Notches and stress concentrations.

AM 350 cyclic fatigue strength cannot be represented by a single universal value. Thin formed components may behave differently from machined bar or forged components. Fatigue testing should reproduce the intended geometry, environment, loading ratio and heat-treatment condition.

For AM 350 fatigue properties for bellows or diaphragms, control of surface defects, edge condition, forming marks and weld quality is especially important.

Elevated-Temperature Strength

AM 350 elevated-temperature properties show that the SCT 850 condition retains substantial strength through intermediate temperatures, although yield and tensile strength decrease as temperature rises.

Typical Elevated-Temperature Tensile Properties

Sub-zero cooled and tempered at 850°F / 454°C:

The data show useful AM 350 high-temperature strength through approximately 900°F / 482°C, with a more pronounced decline by 1,000°F / 538°C.

Typical Stress-Rupture Strength

These values illustrate the interaction between service temperature and tempering condition. Long-duration elevated-temperature use requires evaluation of rupture, relaxation, oxidation, dimensional stability and metallurgical changes.

Room-Temperature Properties After Elevated-Temperature Stress Exposure

Sub-zero cooled and tempered at 850°F / 454°C:

*Specimen broke outside the gauge marks.

Microstructure Overview

AM 350 microstructure is deliberately changed during heat treatment. The principal phases may include:

• Austenite.
• Martensite.
• Retained austenite.
• Delta ferrite.
• Carbides, nitrides or related strengthening precipitates.

The proportion and distribution of these constituents affect strength, elongation, magnetic response, toughness, corrosion behaviour and dimensional change.

The microstructure is therefore not fixed solely by chemical composition. Thermal history and deformation history are equally important.

Austenitic Structure in the Annealed Condition

After solution annealing and rapid cooling, AM 350 has a predominantly austenitic structure. This condition provides:

• Higher elongation.
• Lower yield strength.
• Lower hardness.
• Improved forming capability.
• Reduced magnetic response compared with the hardened condition.

Annealed material is commonly selected for fabrication operations that would be difficult after precipitation hardening. Final conditioning and aging are then performed after forming or rough machining when the component design permits.

Martensitic Transformation During Hardening

The AM 350 martensitic transformation mechanism begins with destabilization of the annealed austenitic structure.

Conditioning alters austenite stability and prepares the material for transformation. Cooling to room temperature and, where required, sub-zero cooling converts a greater proportion of the structure to martensite.

The martensitic matrix provides the foundation for the subsequent precipitation-hardening response. Aging or tempering then develops the final combination of tensile strength, yield strength, hardness and toughness.

Incomplete transformation can lead to lower hardness, reduced yield strength, excessive retained austenite or inconsistent dimensional behaviour.

Delta-Ferrite Content and Its Effect

A controlled quantity of delta ferrite can be present in AM 350. Delta ferrite may affect:

• Hot-working behaviour.
• Weld-solidification behaviour.
• Toughness.
• Fatigue resistance.
• Directional properties.
• Corrosion response.
• Magnetic permeability.

Excessive or non-uniform delta ferrite can produce local property variation. Critical components may therefore require metallographic examination or ferrite assessment according to the applicable specification.

Complete Heat-Treatment Overview

A typical AM 350 heat-treatment process includes several distinct metallurgical stages:

1. Solution annealing to produce a workable austenitic structure.
2. Rapid cooling to preserve the desired annealed condition.
3. Conditioning to destabilize the austenite.
4. Cooling to promote martensitic transformation.
5. Sub-zero cooling where specified.
6. Tempering or aging at the selected temperature.
7. Controlled cooling and dimensional verification.
8. Final hardness, tensile or microstructural testing.

The complete route must be defined by the applicable material or component specification. Treatment temperature, holding time, cooling method, furnace atmosphere, section thickness and load arrangement can all influence the final result.

Annealing or Solution-Treatment Temperature

AM 350 solution annealing is typically performed at:

• 1,850–1,950°F
• 1,010–1,066°C

The material is then cooled rapidly to room temperature.

The purpose of solution annealing is to:

• Restore a predominantly austenitic structure.
• Dissolve selected precipitates.
• Improve ductility.
• Prepare the alloy for forming.
• Establish a consistent starting condition for later hardening.

Slow cooling or uncontrolled thermal exposure can alter phase balance and affect the subsequent transformation response.

Conditioning Treatment

The AM 350 conditioning treatment is used to destabilize the annealed austenite before sub-zero cooling and precipitation hardening.

During conditioning, controlled thermal exposure changes the chemical and structural stability of the austenitic matrix. This allows a greater martensitic transformation during subsequent cooling.

The exact conditioning temperature and holding period must follow the applicable specification. Substitution of an approximate cycle can produce incorrect hardness, retained-austenite content, dimensional change or mechanical properties.

Sub-Zero Cooling Treatment

AM 350 sub-zero treatment promotes the transformation of retained austenite to martensite after conditioning.

The process may also be described as:

• AM 350 sub-zero cooling.
• AM 350 cold treatment.
• Обработка холодом AM 350.
• Cryogenic or below-room-temperature transformation treatment.

The required temperature, holding time, transfer interval and warming procedure should be controlled. Delayed transfer or insufficient cooling can reduce transformation consistency.

Sub-zero cooling is not simply a refrigeration step. It is a metallurgical stage that directly affects AM 350 hardness, yield strength, magnetic behaviour and dimensional stability.

SCT 850 Heat-Treatment Condition

The AM 350 SCT 850 condition refers to material that has undergone the specified conditioning and sub-zero cooling sequence followed by tempering at approximately 850°F / 454°C.

Typical room-temperature properties include:

SCT 850 provides the highest strength and hardness among the listed standard conditions. It is relevant where compact sections, high static strength and resistance to cyclic deformation are important.

SCT 1000 Heat-Treatment Condition

The AM 350 SCT 1000 condition uses the specified conditioning and sub-zero sequence followed by tempering at approximately 1,000°F / 538°C.

Typical room-temperature properties include:

Compared with SCT 850, SCT 1000 generally provides lower tensile strength and hardness but greater ductility. This condition can offer a more balanced strength-toughness relationship.

Double-Aging or DA Treatment

The AM 350 double-aging treatment, also called the AM 350 DA condition, uses a controlled multi-stage aging sequence to develop a selected combination of strength, hardness and dimensional response.

Typical room-temperature properties include:

AM 350 double aging may be considered when the engineering target lies between the strength and hardness levels of SCT 850 and SCT 1000. The exact cycle must remain tied to the relevant specification.

Equalized and Overtempered Condition

The AM 350 equalized and overtempered condition, commonly shortened to AM 350 EOT condition, is intended to modify the alloy’s strength, stability, residual-stress response or machinability through a specified thermal sequence.

EOT material may be relevant when:

• Dimensional stability is prioritized.
• Further machining is required.
• Reduced hardness is beneficial.
• Residual stress must be controlled.
• A later final treatment is planned.

AM 350 EOT condition machinability can be better than machining the highest-strength SCT 850 condition. However, the exact condition designation and final required properties must be stated clearly.

Properties Comparison Between Heat-Treatment Conditions

AM 350 SCT vs Double Aging

SCT treatments use conditioning, sub-zero transformation and tempering. Double aging uses a defined multi-stage aging sequence. They should not be considered interchangeable unless the applicable engineering specification explicitly permits substitution.

AM 350 DA vs SCT Heat Treatment

DA and SCT conditions can produce different combinations of retained austenite, tempered martensite, precipitate distribution, hardness and ductility. Selection should be based on the required property profile rather than hardness alone.

General Corrosion Resistance

AM 350 corrosion resistance is supported by its chromium, nickel and molybdenum content. In many environments, its general corrosion behaviour is comparable to other corrosion-resistant precipitation-hardening stainless steels.

Performance depends on:

• Heat-treatment condition.
• Surface cleanliness.
• Passive-film condition.
• Chloride concentration.
• Temperature.
• pH.
• Crevices and deposits.
• Applied and residual stress.
• Weld condition.
• Surface roughness.

AM 350 corrosion resistance after heat treatment can vary because thermal exposure influences carbide precipitation, phase balance and residual stress.

Passivation after machining or fabrication may help restore a clean chromium-rich passive surface. Passivation does not remove heavy scale, heat tint or deeply embedded contamination unless appropriate cleaning is completed first.

Stress-Corrosion and Intergranular-Corrosion Behaviour

AM 350 stress-corrosion resistance depends on stress level, environment, temperature, microstructure and heat-treatment history.

High-strength stainless steels can be vulnerable to environmentally assisted cracking under unfavourable combinations of tensile stress and corrosive exposure. Particular attention is required in chloride-containing environments and around welds, formed radii or sharply machined features.

AM 350 intergranular-corrosion susceptibility may increase when thermal exposure promotes unfavourable carbide precipitation or chromium depletion at grain boundaries.

Risk control includes:

• Correct solution treatment.
• Approved conditioning and aging cycles.
• Controlled welding heat input.
• Suitable post-weld treatment.
• Removal of heat tint and contamination.
• Passivation where specified.
• Reduction of tensile residual stress.
• Environment-specific corrosion testing.

No stainless steel grade should be described as universally immune to stress corrosion or intergranular attack.

Oxidation Resistance

AM 350 oxidation resistance is supported by its chromium content and is useful during moderate elevated-temperature exposure.

Oxidation behaviour depends on:

• Maximum temperature.
• Exposure duration.
• Heating and cooling cycle frequency.
• Furnace atmosphere.
• Combustion products.
• Surface condition.
• Mechanical loading.
• Scale removal between cycles.

AM 350 high-temperature strength and AM 350 oxidation resistance must be considered together. A component may retain acceptable oxidation resistance while losing part of its original precipitation-hardened strength after prolonged thermal exposure.

Weldability and Post-Weld Treatment

AM 350 weldability is generally workable with controlled procedures, but welding changes the local microstructure and heat-treatment response.

Important considerations include:

• Clean joint preparation.
• Suitable filler-metal selection.
• Controlled heat input.
• Interpass-temperature control.
• Distortion management.
• Shielding-gas quality.
• Heat-affected-zone transformation.
• Post-weld heat treatment.
• Removal of oxide and heat tint.
• Final passivation where applicable.

Welding in the annealed condition can simplify fabrication. The completed assembly may then receive the specified conditioning, sub-zero cooling and aging treatment, provided the design and governing specification allow full post-weld processing.

For AM 350 weldability and post-weld heat treatment, a procedure qualification should account for final strength, hardness, corrosion resistance, weld-metal compatibility and dimensional change.

Machinability and Recommended Material Condition

AM 350 machinability varies substantially by condition. Annealed or EOT material is generally more practical for extensive machining than fully hardened SCT 850 material.

The alloy work-hardens during cutting. Recommended practice includes:

• Rigid machine setup.
• Sharp cutting edges.
• Positive and consistent feed.
• Adequate cutting depth.
• Continuous cutting action.
• Effective coolant application.
• Avoidance of prolonged tool rubbing.
• Controlled tool overhang.
• Frequent monitoring of tool wear.

Typical High-Speed-Steel Machining Guidance

These figures are starting references rather than fixed production parameters. Tool material, machine rigidity, part geometry, hardness and coolant system require adjustment of the final cutting conditions.

Cold Working and Formability

AM 350 cold working is most practical in the annealed condition. The alloy can be formed into sheet, strip, bellows, diaphragm and spring-type geometries before final hardening.

AM 350 work hardening during cold forming increases strength and forming load. Excessive deformation can also influence:

• Martensite formation.
• Springback.
• Residual stress.
• Surface cracking.
• Anisotropy.
• Final heat-treatment distortion.
• Fatigue performance.

Intermediate annealing may be needed for severe deformation. Forming tools should provide controlled radii and smooth surfaces to prevent local damage that could reduce cyclic life.

Hot-Working Temperature and Behaviour

AM 350 hot working requires control of furnace temperature, soaking time, reduction schedule and finishing temperature.

Poorly controlled hot working can cause:

• Surface oxidation.
• Grain growth.
• Non-uniform deformation.
• Delta-ferrite stringing.
• Edge cracking.
• Decarburization or contamination.
• Inconsistent transformation during later treatment.

After hot working, the material normally requires an appropriate solution-treatment cycle to restore the intended starting microstructure.

Exact hot-working temperatures should be established through the relevant product specification and qualified processing procedure rather than a generic grade value.

Dimensional Changes During Heat Treatment

AM 350 experiences dimensional change as a result of:

• Thermal expansion and contraction.
• Austenite-to-martensite transformation.
• Precipitation reactions.
• Residual-stress relief.
• Non-uniform section thickness.
• Furnace-temperature variation.
• Fixturing and support arrangement.

Thin diaphragms, precision rings, bellows and close-tolerance components can be particularly sensitive.

Recommended dimensional-control measures include:

• Consistent starting condition.
• Balanced machining allowance.
• Symmetrical rough machining.
• Controlled heat-treatment loading.
• Suitable fixtures.
• Intermediate dimensional inspection.
• Final finishing after hardening where feasible.
• Verification of flatness, roundness and critical profiles.

Magnetic Behaviour Before and After Hardening

AM 350 magnetic properties change with microstructure.

In the solution-annealed condition, the predominantly austenitic structure generally produces a lower magnetic response. After conditioning, sub-zero treatment and martensitic transformation, magnetic attraction and permeability increase.

Magnetic response can therefore provide a qualitative indication of transformation, but it is not a substitute for:

• Hardness testing.
• Tensile testing.
• Metallographic examination.
• Retained-austenite measurement.
• Specification-based acceptance testing.

Applications involving magnetic sensors, actuators or electromagnetic fields should evaluate the final treated condition rather than the annealed material alone.

Applications and Component Uses

AM 350 applications commonly involve components requiring high strength, corrosion resistance, fatigue capability and controlled heat-treatment response.

Typical uses include:

• Aerospace structural components.
• Gas-turbine components.
• Compressor parts.
• High-strength springs.
• Bellows.
• Diaphragms.
• Actuated-valve components.
• Valve retainers and internal elements.
• Precision clips.
• Flexible couplings.
• Instrumentation components.
• Pressure-responsive elements.
• Thin formed membranes.
• High-strength fastener-type components.
• Elevated-temperature mechanical assemblies.

AM 350 Aerospace Applications

AM 350 aerospace applications benefit from the alloy’s strength-to-section capability, heat-treatment flexibility and performance in cyclic loading.

AM 350 Gas-Turbine Applications

AM 350 stainless steel for gas-turbine components may be used where intermediate-temperature strength, oxidation behaviour and controlled mechanical response are required.

AM 350 Bellows Material

AM 350 bellows material can provide high strength in thin sections, but fatigue performance depends heavily on forming quality, convolution geometry, weld condition and surface finish.

AM 350 Diaphragm Material

AM 350 stainless steel for diaphragms combines formability in the annealed state with increased strength after final hardening.

AM 350 Valve Material

AM 350 stainless steel for actuated valves can be suitable for springs, diaphragms, retainers and flexible operating elements exposed to repeated movement and pressure cycles.

Available Product Forms

AM 350 and UNS S35000 can be referenced in multiple wrought product forms.

Availability of a designation in a specification does not mean every dimension or condition is covered. Product-form scope must be aligned with the applicable standard.

Sizes, Dimensions, Tolerances and Surface Finishes

AM 350 sizes and tolerances depend on the product form, manufacturing route, condition and specification.

Common Dimensional Characteristics

Surface-Finish Considerations

Surface condition can affect fatigue life, corrosion performance, forming quality and inspection results. Depending on product form, finishes may include:

• Hot-worked and conditioned.
• Pickled.
• Ground.
• Peeled.
• Polished.
• Cold rolled.
• Bright finished.
• Descaled.
• Machined.

Final dimensions should account for scale removal, grinding allowance, machining allowance and heat-treatment distortion.

AM 350 Comparison with Similar PH Stainless Steels

AM 350 should not be replaced by another PH stainless steel based only on similar tensile strength. Chemistry, weldability, heat-treatment capability, corrosion resistance, fatigue behaviour, temperature range and dimensional response must also be compared.

Testing, Inspection, Documentation and Technical Disclaimer

Testing for AM 350, UNS S35000 or AISI 633 may include:

• Chemical analysis.
• Tensile testing.
• Yield-strength measurement.
• Elongation and reduction-of-area testing.
• Rockwell hardness testing.
• Metallographic examination.
• Grain-size evaluation.
• Delta-ferrite assessment.
• Retained-austenite analysis.
• Corrosion testing.
• Intergranular-corrosion testing.
• Surface inspection.
• Dimensional inspection.
• Ultrasonic testing.
• Liquid-penetrant testing.
• Magnetic testing where applicable.
• Heat-treatment chart review.
• Traceability verification.

Typical Documentation References

Documentation may identify:

• Grade designation.
• Specification and revision.
• Heat or batch number.
• Chemical composition.
• Product form and dimensions.
• Heat-treatment condition.
• Mechanical-test results.
• Hardness.
• Inspection results.
• Processing route.
• Traceability information.

All numerical data on this page are general or typical engineering references. They are not automatic acceptance limits. Final material requirements must be taken from the applicable drawing, specification revision, approved process and test documentation.

Russian Metals Technical Grade Overview

Russian Metals organizes AM 350 stainless steel information around the factors that directly control engineering performance:

• Correct UNS S35000 and AISI 633 designation.
• Applicable ASTM A693, AMS 5548 or AMS 5745 reference.
• Verified chemical composition.
• Product-form compatibility.
• Annealed, SCT, DA or EOT condition.
• Required strength, hardness and elongation.
• Corrosion and operating-temperature requirements.
• Forming, welding and machining sequence.
• Dimensional and surface requirements.
• Testing and traceability requirements.

This structured approach prevents confusion between annealed AM 350, precipitation-hardened AM 350 and product forms governed by different specifications.