Material Selection for Heat-Treatment Furnace Baskets, Trays, and Fixtures

DAXUN manufactures wrought nickel-alloy and heat-resistant stainless material and fabricates welded heat-treatment furnace baskets, trays, mesh liners, racks, hangers, and locating fixtures from plate, bar, wire, and mesh to approved drawings. This page does not represent DAXUN as a producer of cast furnace fixtures. Where a design calls for a cast grid or basket, the casting grade, foundry route, heat treatment, repair rules, and acceptance criteria require a separate procurement basis.

Why Furnace Fixtures Fail Even When the Alloy Is “Heat Resistant”

The usual failure is not simply that the metal reached a published maximum temperature. Furnace tooling fails when temperature, stress, atmosphere, geometry, and cycling act together.

A basket can look lightly loaded at room temperature yet sag after hundreds of cycles because the relevant property is long-time creep or stress-rupture strength at metal temperature, not room-temperature yield strength. A tray can remain dimensionally sound in clean air but suffer rapid attack in a carburizing furnace because the gas chemistry changes the protective scale and drives carbon into the alloy. A heavy fixture can survive structurally while slowing the load’s heating and quenching response enough to compromise production throughput. A sound weld can become the starting point for distortion when an abrupt section change concentrates thermal strain.

The causal chain is therefore:

> furnace condition -> metal temperature and surface reaction -> time-dependent deformation or section loss -> loss of geometry or load support -> damaged workpieces, handling problems, or unplanned furnace downtime.

ASM describes furnace baskets, trays, hangers, belts, and other accessories as components exposed to the same temperature and atmosphere as the workpieces. It also notes that impurities in process atmospheres can accelerate degradation.^[1] That observation changes the purchase question. The buyer should not ask only, “Which alloy can withstand 1,000 C?” The useful question is, “Which material and fixture design can retain the required shape and load capacity for this atmosphere, cycle, and quench route?”

The Eight Variables That Should Control Material Selection

A technically useful request for quotation begins with the duty cycle, not with an alloy name. The following variables should be resolved before wall thickness, rod diameter, or weld detail is frozen.

Decision variable	What must be stated	Why it changes the selection
Maximum metal temperature	Normal and upset temperature, not furnace setpoint alone	Creep rate, oxidation rate, and phase stability are temperature dependent
Time at temperature	Minutes or hours per cycle and expected cycles	Short peak exposure and long soak service do not consume life in the same way
Atmosphere	Air, combustion gas, endothermic gas, exothermic gas, hydrogen, nitrogen, vacuum, carburizing, carbonitriding, or nitriding	Protective scales and carbon, nitrogen, sulfur, or oxygen reactions differ
Contaminants	Sulfur species, chlorides, alkali salts, boron compounds, furnace-cleaning residues, oils, and carryover	Minor contaminants can govern attack even when the bulk gas appears acceptable
Mechanical load	Workload mass, support spacing, impact during loading, stacking, and lifting points	The fixture must resist creep, bending, local bearing, and handling damage
Thermal cycle	Heating rate, cooling rate, cycle count, and temperature gradient	Repeated differential expansion drives bowing, weld fatigue, and scale spallation
Quench method	Furnace cooling, forced gas, oil, polymer, water, or transfer to a separate quench	Thermal shock, dead weight, drainage, and heat extraction become design variables
Dimensional limit	Maximum bow, twist, mesh opening change, or locating-pin movement	A basket may remain intact but become unusable after small permanent deformation

Two additional questions often decide the economics. First, is the tool expected to be repaired by straightening or rewelding, or replaced as a controlled consumable? Second, is productivity constrained by furnace gross load or by heating and quenching time? A lighter high-strength alloy structure may cost more per kilogram but carry more saleable work and less fixture mass in every cycle.

Alloy 601: Where It Is a Strong Candidate

Alloy 601 is most persuasive when oxidation resistance, cyclic scale adherence, fabrication, and resistance to several furnace atmospheres must be combined in one wrought structure. It is a nickel-chromium-iron alloy with aluminum added to support a protective oxide scale. Special Metals identifies industrial heating applications including baskets, trays, and fixtures and publishes resistance data for oxidation and carburizing environments.^[2]

For a basket designer, this means Alloy 601 can be evaluated for:

• welded bar-frame baskets used in air, controlled atmosphere, or vacuum cycles;
• perforated plate trays and grids where scale resistance and formability are important;
• wire-mesh liners that must retain openings while allowing gas circulation and drainage;
• hangers and locating fixtures used through repeated heating and cooling;
• fixtures entering carburizing, carbonitriding, or nitriding equipment, subject to the actual chemistry and stress level;
• furnace components where Alloy 600 lacks sufficient oxidation margin but the highest creep-strength alloys are not economically justified.

The limitation is equally important. Oxidation performance does not establish allowable load. A design based only on Alloy 601’s nominal temperature capability can still sag if members are too slender, support spans are excessive, welds soften or concentrate strain, or the fixture spends long periods under load in a range where creep is active. Sulfur-bearing or strongly reducing conditions can also change the corrosion mechanism. The responsible engineer must use temperature-dependent mechanical data, process-atmosphere evidence, and either calculation or qualified service history.

What the Material Certificate Does and Does Not Prove

A mill test certificate can verify the ordered alloy, heat, chemistry, product specification, condition, and tests performed on the supplied plate, bar, wire, or mesh. It does not prove that the welded basket will survive a stated number of cycles. Fabrication adds welds, heat-affected zones, residual stress, distortion, local section changes, and surface contamination. The completed fixture therefore needs its own drawing, fabrication procedure, dimensional inspection, and, where risk warrants, weld and proof-load acceptance.

Alloy 600: When the Simpler Nickel Alloy Is Enough

Alloy 600 remains useful where fabrication, general oxidation resistance, and resistance to selected furnace atmospheres matter more than maximizing hot structural strength or cyclic oxidation performance. It is a nickel-chromium-iron alloy with broad industrial service history, but it lacks the aluminum addition that distinguishes Alloy 601’s oxidation behavior.^[3]

Alloy 600 can be a rational choice for lightly loaded baskets, wire products, furnace hardware, and fixtures at moderate metal temperature, particularly when the atmosphere and prior service data are favorable. It may also be chosen when a plant has established welding procedures, spare material, and a known repair history.

It becomes a weaker choice as member stress, exposure temperature, cycle count, or oxidation severity rises. Simply increasing section thickness can restore load capacity, but that adds fixture mass. More dead weight means more energy is spent heating the tool, less work can fit within a furnace gross-load limit, and gas or oil quenching may slow. The lower purchase price of material can therefore be offset by production penalties.

The comparison should not be reduced to “601 is better than 600.” The correct statement is narrower: Alloy 601 usually deserves preference when its aluminum-supported oxidation resistance addresses an actual exposure problem. Alloy 600 can remain adequate when that added margin is unnecessary and the structural duty is modest.

800H and 800HT: Creep-Oriented Iron-Nickel-Chromium Options

800H and 800HT belong in the comparison when long-time creep and stress-rupture behavior is central and an iron-nickel-chromium alloy is acceptable for the atmosphere. They are not interchangeable labels for ordinary Alloy 800.

Special Metals explains that 800H uses controlled carbon and grain size to support elevated-temperature strength, while 800HT applies tighter chemistry controls and a minimum solution heat-treatment requirement within the 800H composition range.^[4] The trademarked 800HT designation also carries producer-specific meaning; a purchase order should use the required UNS designation, material specification, heat treatment, and properties rather than relying on a family nickname.

For furnace trays and fixtures, 800H/800HT may be attractive for sustained high-temperature loads, support frames, and components whose design basis is dominated by creep. Their suitability still depends on atmosphere. A material with favorable creep strength can be the wrong answer if carburization, nitridation, sulfidation, or cyclic oxidation consumes the section or embrittles the member faster than creep would.

The ordered product form matters as well. Plate, bar, wire, and mesh do not automatically share one material standard, heat treatment, grain-size requirement, or mechanical-property table. If several forms are welded into one basket, the bill of materials should identify the applicable specification and condition for each form. The fabrication drawing should also state whether substitute forms or generic Alloy 800 are prohibited.

RA330: A Practical Heat-Treating Alloy, Not Just Generic 330

RA330 is frequently considered for furnace baskets because it balances oxidation and carburization resistance, thermal-shock behavior, fabrication, and cost. Rolled Alloys describes RA330 as a controlled version developed for heat-treatment service and distinguishes it from material supplied only to the generic UNS N08330 chemistry.^[5]

That distinction is commercially important. A drawing that says only “330 stainless” may permit material that meets a broad chemistry designation but does not carry the producer controls or performance history assumed by the designer. If RA330 is required, the purchase order should say so and should identify the applicable product documentation. If generic N08330 is acceptable, the acceptance basis should be equally clear.

RA330 can be competitive for fabricated baskets, trays, muffles, retorts, and furnace hardware in oxidizing and carburizing duty. It is often evaluated where a nickel alloy such as 601 would be technically credible but the project seeks a lower alloy cost or has established RA330 service experience. Conversely, a fixture under severe sustained stress may need a material with greater creep or rupture strength, even when RA330’s environmental resistance is adequate.

No price-per-kilogram comparison is meaningful until section size and expected life are considered. If one alloy requires thicker bars or more cross-bracing, its finished fixture can be heavier and more expensive than the raw-material price suggests.

HAYNES 230 and HR-120: When Less Fixture Mass Has Measurable Value

HAYNES 230 and HR-120 become serious candidates when distortion resistance and high-temperature strength can reduce section size or extend repair intervals. HAYNES 230 is a nickel-chromium-tungsten-molybdenum alloy recognized for high-temperature strength, oxidation resistance, and thermal stability. HR-120 is an iron-nickel-chromium heat-resistant alloy developed to combine elevated-temperature strength with resistance to carburizing and sulfidizing environments.^[6][7]

These materials should not be described merely as premium replacements for Alloy 601. Their value must be tied to a design outcome: smaller bars, thinner plate, less cross-bracing, greater payload, faster heat transfer, lower distortion, or longer time between straightening and repair.

The Published 230-versus-601 Basket Case

Haynes reports a field comparison using two vacuum-furnace baskets of the same basic 33 x 46.5 x 8 in. (approximately 840 x 1,180 x 200 mm) envelope. The HAYNES 230 basket used plate and round-bar sections ranging from 0.25 to 0.4375 in. (6.3 to 11.1 mm), while the Alloy 601 basket used sections from 0.5 to 0.625 in. (12.7 to 15.9 mm). The 230 basket weighed 63 lb (28.6 kg) and the 601 basket 111 lb (50.5 kg), a reported 43% fixture-weight reduction.^[6]

The two baskets were then exposed in vacuum-furnace service for 250 cycles between 1,600 and 1,900 F (870 and 925 C). The documented cooling route used forced nitrogen to 400 F (205 C), followed by air cooling to ambient. Haynes reported visibly better distortion resistance for the 230 basket and, across four load trials, improvements in quench time and quench rate that averaged about 20% and 18%, respectively.^[6]

This is useful engineering evidence, but it is not a universal multiplier. It is one producer-published case with defined basket geometry, member sizes, furnace range, cycle count, loads, and cooling method. It does not prove that every 230 fixture can be 43% lighter, that every plant will gain the reported quench improvement, or that Alloy 601 is unsuitable. A new design must be checked for its own spans, weld joints, handling impact, payload distribution, furnace gas flow, and life target. A prototype or monitored first article is appropriate when a major section reduction is proposed.

HR-120 occupies a related but distinct position. Haynes publishes furnace basket and mesh-liner applications and reports replacements for some 330, 600, and 601 fixtures.^[7] Its atmosphere resistance can be attractive in carburizing or sulfur-bearing service, but trademark grade, product form, heat treatment, and weld procedure must remain controlled. A comparison based only on nominal chemistry is insufficient.

Wrought-and-Welded Fixtures Versus Cast Heat-Resistant Alloys

Neither construction route is inherently superior; geometry, volume, repair philosophy, and loading decide the route. Wrought-and-welded fixtures are assembled from plate, bar, wire, mesh, tube, or formed sections. Cast fixtures create complex grids, ribs, bosses, and load paths in a mold and can be efficient for repeated designs.

Design issue	Wrought-and-welded construction	Cast construction
Design change	Drawings and member sizes can often be revised without new patterns	Pattern and tooling changes may be required
Section integrity	Wrought product generally provides directional worked structure; welds become critical zones	Casting quality, section transitions, porosity, hot tears, and repair history require control
Geometry	Best for frames, grids, mesh liners, hangers, and fabricated trays	Strong for complex ribs, integral bosses, and repeated three-dimensional shapes
Repair	Members can often be cut out and rewelded under an approved procedure	Weld repair depends on cast grade, defect type, procedure, and acceptance rules
Quantity economics	Suitable for one-off and moderate-volume custom fixtures	Tooling can become economical for repeat production
Procurement risk	Product-form certificates and weld traceability must remain linked	Foundry procedure, heat number, casting heat treatment, NDE, and weld-repair records are central

The Nickel Institute documents extensive use of heat-resistant castings for trays, boxes, baskets, fixtures, hearths, and furnace conveying parts.^[8] Cast alloy families are commonly selected by chromium, nickel, carbon, and additions tailored to oxidation, carburization, strength, and casting behavior. Their room-temperature ductility and weld-repair behavior can differ markedly from wrought nickel alloys.

DAXUN’s scope on this page is deliberately limited to wrought-and-welded fixtures. We manufacture and fabricate from specified plate, bar, wire, and mesh to the approved drawing. We do not use a wrought Alloy 601 certificate to imply equivalence to a cast HK-, HP-, HU-, or other heat-resistant casting grade, and we do not represent welded fabrication as a drop-in substitute for an existing casting without engineering approval.

Atmosphere Can Overrule the Temperature Ranking

A material chart based on temperature alone is incomplete because the furnace atmosphere controls the surface reaction. The same fixture can behave differently in air, vacuum, hydrogen, endothermic gas, carburizing gas, nitriding gas, or a sulfur-contaminated environment.^[1]

Oxidizing Service

In air or oxidizing combustion products, a stable, adherent oxide is desirable. Alloy 601’s chromium and aluminum additions support its strong oxidation reputation. HAYNES 230 also offers strong oxidation resistance and high-temperature strength. Cyclic operation remains demanding because repeated expansion and contraction can crack or spall scale, exposing fresh metal.

Carburizing and Carbonitriding Service

Carburizing environments create high carbon activity. Carbon ingress can change the near-surface microstructure, consume alloying elements in carbides, reduce ductility, and complicate welding repairs. RA330, HR-120, Alloy 601, and selected cast grades can all be candidates, but actual gas composition, dew point, temperature, carbon potential, and contaminants should govern the comparison.

Nitriding Service

Nitrogen-bearing atmospheres can form internal nitrides or affect protective scales. Material performance should be supported by producer guidance or relevant plant history for the specific nitriding route. “Nitrogen atmosphere” is not a complete description: inert purge nitrogen, ammonia-bearing nitriding gas, and high-pressure nitrogen quenching impose different chemical and mechanical duties.

Vacuum and Hydrogen

Vacuum minimizes ordinary oxidation but does not remove structural load, thermal gradients, vaporized contaminants, or gas-quench stresses. A vacuum basket may be driven primarily by creep strength and low thermal mass, which is why the HAYNES 230 comparison is relevant. Hydrogen service requires control of purity, moisture, temperature, and compatibility with the workpiece and fixture surface.

Sulfur, Chlorine, Salts, and Carryover

Low concentrations of sulfur-bearing species can be particularly damaging to nickel-rich alloys under some reducing conditions. Chlorides, alkali salts, boron compounds, quench residues, and lubricants carried into the furnace can also create local attack. If fixtures fail near drips, contact points, or contaminated corners rather than uniformly, chemical carryover should be investigated before buying a thicker version of the same alloy.

Creep, Stress Rupture, and Distortion: Three Different Questions

A fixture design needs all three concepts, because they answer different questions.

• Creep asks how much permanent strain accumulates under stress at temperature over time.
• Stress rupture asks how long a material can sustain a specified stress and temperature before rupture.
• Distortion resistance describes the finished structure’s ability to retain usable geometry under creep, thermal gradients, residual stress, handling, and cyclic loading.

Room-temperature tensile strength cannot replace these data. Nor can a single elevated-temperature yield value predict 5,000 cycles. Long-life design should use appropriate creep or rupture data and a defensible stress model. The model should include fixture self-weight, payload distribution, dynamic loading during transfer, section loss allowance, stress concentrations, and the reduction associated with welded joints where applicable.

Support spacing often matters as much as alloy. Bending stress and deflection rise sharply when a span is increased. A light grid with well-placed supports can outperform a heavier grid with poor load paths. Cross-members should carry loads into lift points without forcing welds to act as hinges. Locating pins need enough hot stiffness to hold part position but should not overconstrain thermal expansion.

Why Dead Weight Affects Process Quality

Fixture mass is process mass. Every cycle must heat it, cool it, and move it. A basket that is structurally durable but unnecessarily heavy can reduce productivity in four ways:

1. It consumes furnace gross-load capacity that could otherwise carry saleable parts.
2. It adds thermal inertia, which can extend heat-up or equalization time.
3. It obstructs gas circulation or quench flow when large members and dense grids are used.
4. It stores heat during quenching, potentially slowing the cooling response of adjacent workpieces.

The Haynes comparison gives a concrete example of why this matters, but the effect must be measured in each furnace.^[6] Load thermocouples, quench probes, cycle records, and part-hardness or microstructure results provide better evidence than fixture weight alone. When redesigning a basket, production qualification should confirm that load arrangement and circulation still achieve the required heat-treatment result.

Quench Method Changes Both Material and Geometry Requirements

The cooling route can be more damaging than the heating soak. Forced-gas quenching creates pressure and flow loads while rapidly developing thermal gradients. Oil or polymer quenching introduces buoyancy, drag, drainage, residue, and fire-management considerations. Water quenching imposes severe thermal shock and requires rapid drainage without trapping vapor. Furnace cooling is gentler but may not satisfy the workpiece metallurgy.

The fixture drawing should therefore address:

• drainage holes and orientations that do not retain liquid;
• open area needed for gas or liquid flow;
• part spacing and shielding;
• lift-point strength at hot and cold conditions;
• differential expansion between mesh, frames, and solid plates;
• quench-induced bending of broad panels;
• whether the basket is immersed loaded or unloaded;
• post-quench cleaning and inspection.

A material’s oxidation or carburization resistance cannot compensate for a tray geometry that blocks the quenchant. Conversely, a highly open design may need stronger members or a higher-creep-strength alloy to retain shape.

Weld Design Is Part of Alloy Selection

A wrought alloy cannot deliver its published performance if the joint design concentrates strain or the welding procedure contaminates and distorts the structure. Material selection and weld design should be reviewed together.

Good practice begins with confirmed base-metal and filler-metal identities, clean joint surfaces, suitable shielding, controlled heat input, and a qualified procedure appropriate to the alloy combination and project requirements. Dissimilar joints need specific engineering review; choosing a nominally compatible filler does not establish equal creep strength or equal atmosphere resistance across the joint.

For furnace baskets and trays, practical details include:

• keeping welds away from the highest bending moment where geometry permits;
• avoiding abrupt transitions between thick bars and thin mesh or sheet;
• allowing members to expand without forcing one rigid corner to absorb all strain;
• using continuous or intermittent welds only after considering atmosphere traps, crevices, and distortion;
• defining weld size by load and hot-service behavior, not by room-temperature appearance;
• removing iron contamination and residues that can become initiation sites for oxidation;
• recording any repair welding so repeated heat-affected-zone damage is visible.

Overwelding is not free insurance. Extra weld metal adds restraint, thermal mass, residual stress, and distortion. A clear load path and repeatable procedure are more valuable than indiscriminately larger welds.

Inspection Should Track Fitness for Use, Not Appearance Alone

A basket should be retired or repaired based on defined limits, not on whether it still looks serviceable from across the shop. ASM’s published proceedings emphasize periodic inspection and monitoring of alloy trays and fixtures as part of maintaining heat-treatment productivity.^[9]

An inspection plan can include the following controls:

Stage	Recommended checks	Evidence retained
Incoming material	Grade, specification, heat, dimensions, surface, and material condition	Mill test certificates, receiving report, heat map
Fabrication	Member size, joint preparation, filler identity, welder/procedure status, distortion control	Traveler, weld map, consumable records
Final manufacture	Overall dimensions, flatness, squareness, opening size, lift points, surface condition	Dimensional report, photographs, NDE report when specified
First article	Fit in furnace, handling clearance, loaded deflection, heat-up and quench response	Trial report, load records, thermocouple or process data
In service	Bow, twist, cracks, weld separation, section loss, scale, mesh damage, lifting-point wear	Cycle log and periodic inspection record
Repair or retirement	Repair limits, maximum straightening cycles, weld-repair approval, rejection dimensions	Disposition and traceable repair record

Visual testing is useful for surface cracking, broken wires, scale buildup, and weld separation. Liquid penetrant testing may be specified for accessible nonporous surfaces, but the method, precleaning, temperature, acceptance criteria, and post-cleaning must be defined. Dimensional gauges or reference fixtures can detect gradual bow and twist. Proof loading may be appropriate for new or repaired lifting structures, but the load, temperature, support arrangement, and acceptance criteria require engineering approval.

No NDE method proves remaining creep life by itself. When service is severe, trend data are more valuable: cycles, maximum temperatures, upset events, repairs, measured distortion, and section loss. A basket that has survived 1,000 cycles in one furnace is not automatically qualified for a hotter furnace or a heavier payload.

Common Failure Modes and the Corrective Question

The shape of the damage often points toward the controlling variable.

Observed problem	Likely contributors	Question before replacement
Progressive center sag	Creep, excessive span, high payload, overheated zone	Can support spacing, section modulus, alloy creep strength, or payload distribution be changed?
Twisted frame	Uneven heating/cooling, rigid joints, asymmetric load	Is thermal expansion constrained or gas flow uneven?
Cracks beside welds	Stress concentration, filler mismatch, repair history, thermal fatigue	Does the weld detail and procedure suit cyclic hot service?
Rapid thinning or pitting	Atmosphere contaminant, salt or chemical carryover	What deposit or gas species is present at the attack site?
Mesh tearing	Embrittlement, excessive part contact, quench drag, inadequate wire size	Is the liner carrying structural load it was not designed to carry?
Heavy scale and blocked openings	Oxidation, poor cleaning, unsuitable atmosphere resistance	Is scale adherence or the cleaning interval controlling life?
Workpiece hardness variation	Excess fixture mass, shielding, poor spacing, blocked quench flow	Did the basket redesign change thermal or quench uniformity?
Repeated lift-point damage	Impact, hot handling, poor load path, undersized attachment	Are real handling loads included in the design?

Changing alloy without identifying the mechanism can repeat the failure at a higher material cost. A useful failure review preserves photographs, failed sections, furnace records, atmosphere data, load configuration, cycle count, and repair history. Deposits can be analyzed when contamination is suspected. Metallography and hardness may help identify carburization, nitridation, overheating, or weld-related changes, but the test plan should be chosen around the suspected mechanism.

A Practical Material-Screening Matrix

The matrix below is a screening tool, not a specification or life guarantee. It summarizes why each family enters the discussion and what must be verified before selection.

Material family	Why it may be selected	Principal caution
Alloy 600	Fabricability and established service in moderate furnace duty	Lower oxidation and hot-strength margin than some alternatives in severe cyclic service
Alloy 601	Strong oxidation resistance, useful resistance in several furnace atmospheres, wrought fabrication	Creep and distortion still require structural verification; not universal for sulfur-bearing or extreme-load service
800H/800HT	Controlled high-temperature strength and creep-oriented product conditions	Exact designation, heat treatment, product form, and atmosphere suitability must be controlled
RA330	Heat-treat-industry balance of oxidation, carburization, thermal shock, fabrication, and cost	Do not assume generic N08330 is identical to trademarked RA330 performance
HAYNES 230	High creep/rupture strength and oxidation resistance can enable lighter structures	Higher material cost and fabrication requirements must be justified by design and productivity
HAYNES HR-120	Elevated-temperature strength with resistance to carburizing and sulfidizing environments	Trademark grade, product route, joint design, and actual atmosphere require qualification
Cast heat-resistant alloys	Complex integral geometry and repeat-production economics	Casting quality, repair, heat treatment, NDE, and grade-specific ductility require foundry controls

Selection should proceed in two gates. Gate one eliminates materials that cannot tolerate the atmosphere and temperature. Gate two compares the surviving candidates by creep strength, section size, weldability, expected repair cycle, fixture mass, availability, and total operating cost. Reversing those gates by choosing the cheapest alloy first often produces false economy.

DAXUN Wrought-and-Welded Manufacturing Scope

DAXUN supplies the material and manufactures the finished welded fixture within one traceable production route. Our applicable scope includes custom baskets, trays, grids, mesh liners, racks, hangers, locating frames, and support assemblies made from specified wrought plate, bar, wire, and mesh.

For a technically controlled order, DAXUN can manufacture to the approved drawing and agreed inspection plan with:

• material identification by grade, product form, heat, specification, and condition;
• cutting, forming, drilling, perforating, mesh preparation, fitting, and welding;
• control of filler identity and fabrication records;
• dimensional inspection of critical interfaces, flatness, squareness, lift points, and openings;
• visual inspection and additional NDE when stated in the purchase order;
• surface cleaning and project-specific packaging;
• mill test certificates and lot traceability linked to the finished assembly;
• third-party inspection or customer witness when agreed before manufacture.

This scope has clear boundaries. DAXUN does not claim on this page to cast HK, HP, HU, or other heat-resistant cast fixtures. We do not assign a safe working load, hot allowable stress, cycle life, or furnace qualification without the necessary design basis. A finished fixture’s suitability remains subject to the approved drawing, furnace duty, engineering calculations or qualification plan, and the purchaser’s acceptance requirements.

What to Put on the Drawing and Purchase Order

A complete drawing prevents the supplier from guessing which requirement matters most. At minimum, include:

1. Fixture type and drawing revision.
2. Alloy designation and UNS number for every material form.
3. Material specification, condition, and certificate requirements.
4. Plate, bar, wire, mesh, and formed-section dimensions.
5. Maximum workpiece load, load distribution, stacking arrangement, and lifting method.
6. Normal and upset metal temperatures, soak time, and expected cycles.
7. Furnace atmosphere, carbon potential or nitriding route where relevant, dew point, pressure, and known contaminants.
8. Heating, transfer, and quench sequence, including gas pressure or liquid quenchant.
9. Maximum allowable bow, twist, flatness change, opening change, and locating-point movement.
10. Weld symbols, filler requirement, procedure qualification basis, and permitted repair.
11. NDE method, coverage, timing, acceptance criteria, and reporting.
12. First-article, proof-load, fit, or process-trial requirements.
13. Surface condition, cleanliness, marking, packaging, quantity, and delivery destination.

When replacing a failed fixture, also send the old design, service temperature history, atmosphere data, payload, cycle count, failure photographs, measured distortion, and repair record. Those details are often more valuable than the old alloy name.

Frequently Asked Questions

Is Alloy 601 the best material for every heat-treatment basket?

No. Alloy 601 is a strong general candidate for oxidizing and several controlled-atmosphere duties, but a highly stressed vacuum basket may benefit from HAYNES 230, a carburizing fixture may favor RA330 or HR-120 depending on conditions, and a complex repeated geometry may suit a cast heat-resistant alloy. The furnace duty and design decide.

What is the difference between a heat-treatment basket and a furnace tray?

The names overlap. A basket normally has an open frame, mesh, or perforated enclosure for retaining parts during handling and processing. A tray generally provides a flatter support surface or grid. Both can be load-bearing furnace fixtures and both require hot-strength, atmosphere, flow, and distortion analysis.

Why does a basket sag without cracking?

Sagging is commonly a creep problem. Under sustained stress at elevated temperature, permanent strain accumulates even when the stress is below the room-temperature yield strength. Excess span, uneven load, section loss, overheating, and softened or highly restrained weld zones can accelerate it.

Can thicker Alloy 600 replace Alloy 601 or HAYNES 230?

Sometimes, but thickness affects more than strength. It increases fixture weight, thermal inertia, heating demand, and potential quench obstruction. It also does not correct an atmosphere-compatibility problem. Compare the finished design, cycle effect, and expected life rather than equal material thicknesses.

Are HAYNES 230 baskets always 43% lighter than Alloy 601 baskets?

No. The 43% figure belongs to a specific Haynes-published case with defined dimensions and member sizes. It demonstrates what higher hot strength enabled in that design; it is not a universal section-reduction rule.^[6]

Should a carburizing basket use a high-nickel alloy?

Not automatically. Nickel, chromium, silicon, aluminum, carbon, and other additions influence carburization resistance, oxidation, strength, and fabrication. Carbon potential, temperature, contaminants, stress, and cycle history must be considered together. Producer data or relevant service evidence should support the selection.

Can an MTC certify the completed furnace fixture for a cycle life?

No. The mill test certificate verifies the supplied material to the stated purchase requirements. Cycle life also depends on geometry, welds, stress, atmosphere, temperature history, handling, quenching, and acceptance criteria. These require design and finished-product controls.

What inspection should be performed during service?

Use scheduled visual and dimensional checks focused on weld cracks, broken mesh, bow, twist, section loss, scale, lift-point wear, and fit. Record cycle count, upset temperatures, repairs, and measured changes. Additional NDE or metallurgical examination should be selected for the suspected failure mechanism.

Request a Technically Reviewable Quotation

Send DAXUN the drawing, alloy preference if one exists, material forms, dimensions, quantity, load, furnace temperature, soak time, atmosphere, contaminants, expected cycles, quench route, allowable distortion, welding requirements, inspection plan, documentation requirements, and delivery destination. We will review the request as a wrought-and-welded fixture project and identify any missing material, fabrication, or acceptance details before manufacture.

Related technical pages:

• Inconel 601 Sheet and Plate
• Inconel 601 Tube and Pipe
• Inconel 600 vs Inconel 601
• Furnace Retort Material Selection
• Furnace Radiant Tube Material Selection

Technical Sources

1. ASM International, Materials for Heat-Treating Furnace Parts, Trays, and Fixtures, ASM Handbook, Volume 4B, 2014.
2. Special Metals, INCONEL Alloy 601 Technical Bulletin.
3. Special Metals, INCONEL Alloy 600 Technical Bulletin.
4. Special Metals, INCOLOY Alloys 800H and 800HT Technical Bulletin.
5. Rolled Alloys, RA330 Alloy Technical Information.
6. Haynes International, HAYNES 230 and HR-120 Alloys for Lightweight Vacuum Heat-Treat Baskets.
7. Haynes International, HAYNES HR-120 Alloy.
8. Nickel Institute, Heat-Resistant and Corrosion-Resistant Castings: Engineering Properties and Applications, Publication 266.
9. ASM International, Checks and Balances: Practical Guidelines for Alloy Trays and Fixtures Fit and Function in Heat Treatment, Heat Treating 2023 Proceedings.

Technical Accuracy Statement

This article provides a material-screening and procurement framework, not a fixture design code, safe-working-load certification, furnace-process qualification, or service-life guarantee. Alloy properties cited from producer literature are reference information tied to the stated material, product form, condition, and test method. Contract acceptance must follow the approved drawing, purchase order, applicable material specifications, qualified welding procedures, and agreed inspection criteria. Furnace temperature is not automatically the fixture metal temperature. Atmosphere descriptions must include relevant chemistry and contaminants. Trademarked grades such as RA330, HAYNES 230, HAYNES HR-120, and INCOLOY 800HT should be ordered by the exact approved designation and procurement requirements. Final material selection and structural adequacy remain the responsibility of the purchaser’s qualified engineering authority.

Last reviewed: August 17, 2026