430 Stainless Steel Wire for Heat Exposure and Thermal Cycling

430 is often ordered as the cheaper alternative to 304. In parts that cycle between hot and cold, the real reason is different: thermal expansion. 430 is ferritic with a linear expansion coefficient around 10.4 x 10-6 /K, against roughly 17.3 x 10-6 /K for austenitic 304. Over a heating cycle that difference decides how much stress builds at a fixed weld or a clamped joint.

This wire is annealed and soft at 450-650 N/mm2, supplied bright annealed or bright drawn from 0.15 mm to 12 mm. It carries 16-18% chromium, so a chromium oxide layer forms and re-forms after each cycle instead of needing to be replaced.

Two limits belong in the same conversation. Prolonged holding around 475 C embrittles ferritic grades, and welding grows the grain structure and lowers toughness at the joint. Both are design constraints, not reasons to avoid the grade.

Product Specifications

Why 430 in Heat Service

Lower expansion means lower thermal stress

A wire frame fixed at both ends and heated will push against its anchors in proportion to its expansion. At the same temperature rise, 430 moves roughly 40% less than 304, which is the difference between a frame that stays flat and one that bows or cracks its weld.

Oxide layer that survives cycling

Chromium in the 16-18% range forms a thin oxide that re-forms after each thermal cycle. This is why 430 is used for supports and brackets that see repeated heating rather than one continuous soak.

Two limits to design around

Holding near 475 C for long periods embrittles ferritic 430, so continuous service in that band should be reviewed with the end user. Welding also coarsens the grain and reduces toughness at the joint, which means heat input and joint location have to be planned rather than assumed.

Applications

Heating element supports and brackets

Wire forms that locate and space resistance elements, where repeated heating cycles and modest mechanical load are the design case.

Grills, burners and oven parts

Racks, trivets and burner frames that see radiant heat and occasional flame contact, with no chloride detergents in service.

Magnetic locating and shielding parts

Components that must be held or positioned magnetically during assembly, where an austenitic grade would not respond.

Product Advantages

• Expansion about 40% lower than 304 - less thermal stress at fixed joints and welds over the same temperature rise.
• Chromium oxide layer that re-forms - 16-18% Cr supports repeated heating instead of a single long soak.
• Nickel-free cost structure - the saving is real at coarse diameters, where nickel dominates the price.
• Ferromagnetic - parts can be handled, located or separated magnetically.
• Annealed for forming - 450-650 N/mm2 keeps 0.15-12 mm wire bendable around element spacings and frame corners.
• Limits stated honestly - avoid prolonged service near 475 C, control weld heat input, and specify 304 or 316L where moisture, detergent or chlorides are present.

Quality Control

Rod grade is verified before drawing, diameter is measured inline with end-of-coil sampling, and tensile and elongation are tested per heat per ISO 6892-1. Surface is inspected for scale, scratches and die lines, and coil build is checked before packing.

Selection and Ordering Notes

1. State the service temperature and whether it is continuous or cyclic, so the 475 C band can be reviewed.
2. Give the fixing method at both ends of the part, which sets how much expansion has to be absorbed.
3. Confirm whether any joint is welded, and where it sits relative to the hot zone.
4. Confirm the atmosphere: dry heat is 430 territory; moisture, detergent or chlorides call for 304 or 316L.
5. Provide sizes and annual volume for a tolerance and packing review.

Send the grade, diameter, service temperature and fixing arrangement for technical confirmation and quotation.