Type 430 stainless steel

Identity and selection

ATI's ASTM A240 Type 430 sheet and strip listing gives 22% minimum elongation, with a thickness note of 20% at 1.27 mm and thinner. It also lists 450 MPa minimum tensile, 205 MPa minimum yield, and 89 HRB maximum. Use the ordered edition and its test provisions for acceptance. ATI sheet and strip summary

Type 430 is UNS S43000, a ferritic stainless steel. ATI's sheet/strip product page lists 16–18% chromium and carbon ≤0.12%, with other controlled elements. Outokumpu identifies its Moda 430/4016 as an unstabilized, non-hardenable ferritic product associated with EN 1.4016, used particularly in mildly corrosive indoor environments. ATI product page, Outokumpu Moda range

Keep ordinary 430 separate from stabilized 430Ti, free-machining variants and austenitic 304. A shared number fragment does not establish equivalent fabrication behavior. Specify the complete grade, governing standard and edition, form, dimensions, supplied condition, finish and inspection documents.

Select against the component's actual exposure and manufacturing route. For trim or a formed appliance panel, appearance and drawability may govern alongside corrosion; for a load-bearing part, the applicable design rules and delivered material evidence must also be established.

Mechanical values: retain the product and standard

ATI's technical bulletin separately reports typical room-temperature properties of cold-rolled, annealed sheet/strip: for 0.02–0.06 inch thickness, 0.2% yield strength 44–54 ksi, tensile strength 70–79 ksi, and elongation in 2 inches 21–34%. These summarized longitudinal/transverse results are characterization data, not substitute acceptance minima. ATI bulletin, mechanical properties and footnotes

Do not combine a typical tensile result, a minimum yield requirement and an elongation measured on a different gauge length into an invented material condition. Preserve test direction, temperature, thickness, finish, cold reduction and certificate identity with calculation inputs. A visible finish may include processing that changes properties.

Corrosion and surface acceptance

Outokumpu reports lower resistance to localized chloride corrosion for Moda 430/4016 than for its 304/4301 or 304L/4307 products. Its strong ferritic resistance to chloride-induced stress corrosion cracking does not remove pitting or crevice-corrosion concerns. Moda bulletin, corrosion discussion

Record chlorides, temperature, wet/dry cycles, deposits, crevices and cleaning chemicals. Include hidden joints and shutdown conditions. Define an acceptable cosmetic condition separately from a structural corrosion allowance; an application name such as “kitchen equipment” does not qualify every cleaning or food-contact duty.

For an appearance-critical part, approve a finished sample after the intended forming, joining and cleaning sequence. Keep grain direction, scratch acceptance and inspection lighting in the purchasing record. Surface treatment does not change the bulk grade into a more highly alloyed stainless.

Forming and welding

ATI describes earing in deep drawing and roping, surface striations parallel to the rolling direction, during some forming operations. Its relatively low work-hardening rate also limits stretch forming compared with austenitic grades. ATI bulletin, deep drawing and roping

Qualify blank orientation, tooling, lubrication, radii and cosmetic acceptance on representative stock. Tensile elongation alone cannot predict the outcome of a complex draw. Inspect the final surface and dimensions after operations that can alter them.

Outokumpu explicitly says Moda 430/4016 is not intended for the as-welded condition and gives 750–800°C postweld heat treatment for adequate weld-region ductility and corrosion resistance. This is producer guidance requiring a qualified component process. Moda bulletin, weldability

Before selecting it for a welded assembly, resolve filler, joint geometry, restraint, thermal sequence, final properties and cleaning. Establish whether the assembly can tolerate the required treatment and resulting distortion. If it cannot, reconsider the material or joint rather than assuming the starting sheet properties apply across the weld.

Thermal exposure and a bounded calculation

ATI's oxidation guidance gives 870°C intermittent and 790–815°C continuous exposure, while emphasizing atmosphere, cycling and design dependence. Those values do not establish permissible stress, creep life or retained toughness. Its bulletin also warns of reduced impact properties after several days at 425–540°C. ATI bulletin, oxidation and impact sections

Keep oxidation, mechanical loading and thermal aging as separate selection questions. Record metal temperature, time and cycles, including fabrication and upset exposure; one maximum-temperature field cannot represent all of them.

Original free-expansion example: Moda's reference coefficient is 10.0 × 10⁻⁶/K over 20–100°C. A uniformly heated, freely expanding 1,000 mm strip over that interval gives ΔL = 1000 × 10.0 × 10⁻⁶ × 80 = 0.80 mm. Restraint, thermal gradients, joints and buckling are excluded; this is not a stress or clearance qualification. Moda bulletin, table 6

Procurement record and source versions

Retain producer, heat/lot, standard edition, form, thickness, condition, finish, certificate, processing route and required final inspections. Record approved substitutions against the complete requirement, including weld and surface acceptance.

ATI's inspected bulletin prints Version 1, 13 July 2012. The inspected Moda bulletin prints October 2022; its URL modification date is not its technical edition. No technical revision date was verified for the live product pages. These references do not establish the current contractual standard edition.

See grades, tempers and conditions.