UGI 4435 IRH: Solution‑Annealed & Work‑Hardened Stainless Steel – Superior Corrosion Resistance & Skin‑Friendly

UGI 4435 IRH is an austenitic stainless steel (not magnetic) with a high Mo content and produced by a special method to optimize its cleanliness. Its composition provides it with very good corrosion resistance and is perfectly suited for prolonged contact with the skin. This grade also offers improved polishability, thanks to its inclusion population and its microstructure, adapted and controlled.

The chemical composition of UGI 4435 IRH is optimised to ensure primary ferritic solidification limiting hot workability problems and risks of crack formation at high temperature during welding, while providing it with a structure almost 100% austenitic at room temperature.

Grain size as per ASTM E-112: ≥ 5 (≥ 4 if need of guarantee of residual ferrite < 0.5%).

Cleanliness as per DIN 50602, "M" method:

Sulphides (SS) + Oxides in Alignment (OA) + Silicates (OS): less than 4%

Dispersed or globular oxides (OG): less than 1%

Properties

General

Property	Value
Density	8 g/cm³

Mechanical

Property	Temperature	Value	Comment
Elastic modulus	20 °C	200 GPa
	100 °C	194 GPa
	200 °C	186 GPa
	300 °C	180 GPa
	400 °C	172 GPa
	500 °C	165 GPa
Elongation		25.0 - 30.0 %	min., depending on the size
Tensile strength		500.0 - 950.0 MPa	min., depending on the size

Thermal

Property	Value	Comment
Coefficient of thermal expansion	0.000016 1/K	20 to 100°C
	0.0000165 1/K	20 to 200°C
	0.000017 1/K	20 to 300°C
	0.0000175 1/K	20 to 400°C
	0.000018 1/K	20 to 500°C
Specific heat capacity	500 J/(kg·K)
Thermal conductivity	15 W/(m·K)

Electrical

Property	Value
Electrical resistivity	7.500000000000001e-10 Ω·m

Chemical properties

Property	Value	Comment
Carbon	0.03	max.
Chromium	17.0 - 19.0 %
Manganese	2.0	max.
Molybdenum	2.5 - 3.0 %
Nickel	12.5 - 14.0 %
Nitrogen	0.11	max.
Phosphorus	0.045	max.
Silicon	1.0	max.
Sulfur	0.03	max.

Technological properties

Property

Application areas

Watchmaking, Pharmaceuticals

Cold Forming

Wire drawing – Shaping : The 4435 IRH grade has good cold forming capability. Its high cold work hardening compared with non-austenitic grades induces the use of appropriate tools. Cold working can make the grade very slightly magnetisable through the formation of strain-induced martensite.

Bending – Forming: Good bending and forming capability.

Corrosion properties

Uniform corrosion: Its higher molybdenum content provides it, in reducing mineral acids, with better uniform corrosion resistance than the conventional austenitics 1.4307 (304L) and 1.4404 (316L).

Pitting corrosion and crevice corrosion: It has very good corrosion resistance behaviour for a great majority of natural exposures (rural, urban and industrial). This grade, with high molybdenum content, offers among the best pitting and crevice corrosion resistance of the austenitic family. Its very good corrosion resistance behaviour means it easily complies with the EN1811 standard relating to nickel release.

Intergranular corrosion: Due to its low carbon content, this grade resists intergranular corrosion after welding and after sensitizing heat treatment as specified in the standards (ASTM A262-75 Practice E; DIN EN ISO 3651-2).

General machinability

Thanks to control of its inclusion population and microstructure, UGI 4435 IRH can retain a satisfactory machinability level while ensuring optimal polishability for the grade.

Hot forming

Forging: The grade can be hot-worked at between 900°C and 1250°C and then cooled rapidly, in water or air. Hot forming is generally followed by a solution annealing or quenching (see recommendations in the corresponding section).

Other

Available products:

Product	Shape	Finish	Tolerance	Dimensions (mm)
Bar	Round	Rolled & descaled	k13	Ø 13 to 130
		Turned	10 + 11	Ø 22 to 130
		Ground	7 + 8 + 9 + options	Ø 2 to 130
		Drawn	9	Ø 2 to 30
		Black bar	+/- 1% of ø	Ø 23 to 135
	Hexagonal	Drawn	10 + 11	Hex. 3 to 55
Wire Rod	Round	Rolled		Ø 5 to 32
	Round	Rolled & pickled		Ø 5 to 32
	Hexagonal	Rolled & pickled		Hex. 12.4 to 28
Billet	Square	As-rolled or as-heat-treated		50 to 120

Other possible options. Please consult the supplier.

Surface Treatment

Type	Medium	Comments
Pickling	6 – 25% HNO3 + 0.5 – 8% HF	In the annealed state only and at high temperature
Passivation	20 – 50% HNO3	At high temperature

Welding

UGI 4435 IRH can be resistance welded (spot or seam welding) by any type of arc process (MIG, TIG, submerged arc, covered electrode), by laser, electron beam, etc.

UGI 4435 IRH is balanced to be on the boundary of primary ferritic solidification in order to ensure a minimum of residual ferrite in the welding region while limiting its risk of crack formation at high temperature during arc welding. In laser welding, the risk of crack formation at high temperature is greater than with arc welding, and the welding parameters should be adjusted as well as possible on a case by case basis to limit this risk.

Where a filler wire is used to weld UGI 4435 IRH to itself, preferably choose an ER316L(Si) – 1.4430 wire.

The protection gases in arc welding should preferably be:

In MIG: Ar (+ possibly He) + 2% to 3% O₂ or CO₂

In TIG: Ar (+ possibly He)

No preheating or post-welding heat treatment is required. Interpass temperatures not exceeding 150°C should be complied with.

UGIMA® 4362 Work Hardened Stainless Steel – Enhanced Machinability & Superior Corrosion Resistance UGI® 316Ti Stainless Steel – High‑Temperature, Non‑Magnetic, Solution Annealed

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