UGI 4057 AIR: High-Performance Martensitic Stainless Steel for Superior Corrosion Resistance

UGI 4057 AIR is a martensitic stainless steel with Ni addition. Its 15% Cr content ensures a higher corrosion resistance than classical martensitic stainless steels like AISI 410 or 420. The balance between alloying ele-ments, Cr, Ni and C, in UGI 4057 AIR has been carefully chosen to obtain an almost fully martensitic struc-ture after austenitization (with limited amounts of retained austenite and delta ferrite) to develop full strength. This grade is employed preferentially in quench and tempered condition that offers a wide range of mechanical properties depending on the tempering temperature.

The microstructure in quench and tempered condition is fully martensitic with fine chromium carbides. The delta ferrite is nearly totally eliminated by hot rolling and austenitization (delta fraction < 5 % is guaranteed). The following microclealiness, according to ASTM E45/A is guaranteed on UGI 4057 AIR. For applications requiring an improved microcleanliness UGI 4057 AIR also exists in ESR refined version.

Type		A		B		C		D
Rating		Thin	Heavy	Thin	Thick	Thin	Thick	Thin	Thick
Rating		< 2	< 2	=< 2	< 2	=< 2	< 2	=< 2	< 2

For applications requiring an improved microcleanliness UGI 4057 AIR also exists in ESR refined version.

UGI 4057 AIR is a ferromagnetic grade at room temperature until 727°C (Curie transition). Its magnetic prop-erties are semi-hard, and are significantly changed by tempering. The evolution with tempering is shown on the graph provided in the picture part of the datasheet.

Properties

General

Property	Temperature	Value
Density	20 °C	7.71 g/cm³
	100 °C	7.69 g/cm³
	200 °C	7.66 g/cm³
	300 °C	7.64 g/cm³
	400 °C	7.6 g/cm³

Mechanical

Property	Temperature	Value	Comment
Elastic modulus	20 °C	215 GPa
	100 °C	212 GPa
	200 °C	205 GPa
	300 °C	200 GPa
	400 °C	190 GPa
Hardness, Brinell		293.0 [-]	min.

Thermal

Property	Value	Comment
Coefficient of thermal expansion	0.0000106 1/K	20 to 100°C
	0.0000112 1/K	20 to 200°C
	0.0000117 1/K	20 to 300°C
	0.0000121 1/K	20 to 400°C
Specific heat capacity	460 J/(kg·K)
Thermal conductivity	25 W/(m·K)

Electrical

Property	Value
Electrical resistivity	7e-07 Ω·m

Chemical properties

Property	Value	Comment
Carbon	0.12 - 0.2 %
Chromium	15.0 - 17.0 %
Copper	0.5	max.
Manganese	1.0	max.
Molybdenum	0.30000000000000004	max.
Nickel	2.0 - 3.0 %
Phosphorus	0.025	max.
Silicon	1.0	max.
Sulfur	0.005	max.

Technological properties

Property

Application areas

UGI 4057 AIR is frequently used in highly stressed parts where good corrosion resistance is important in de-sign, such as aircraft fittings, pump shafts and valve parts. It also meets the requirements of EN10272 with respect to pressure vessels.

Corrosion properties

This alloy has a good atmospheric corrosion resistance and is one of the best standard martensitic grades for corrosion resistance; only structurally hardened grades such as UGIMA® 4542 have a higher resistance (among martensitic grades). It is also resistant to certain petroleum and organic products.

Environment	Behaviour/ Use
Nitric acid	GOOD
Phosphoric acid	Restricted use
Sulphuric acid	Restricted use
Acetic acid	Restricted use
Sodium carbonate	Average
NaCl (fog test)	Average
Humidity	GOOD
Sea water	Restricted use

N.B. : the corrosion resistance of a stainless steel depends on many factors related to the composition of the corrosive atmosphere (chloride concentration, presence or absence of oxidizing agents, temperature, pH, ag-itation or no agitation, and so on), as well as to the preparation of the material (surfaces free from metal par-ticles, surface finish, such as hardening, polishing, and so on). Precautionary measures should be taken for certain tests such as the sodium chloride fog test (ISO 9227): for example marking labels (that might cause corrosion run-outs and reduce the test resistance time) should not be used on the sample.

Heat Treatment

Heat treatments carried out on UGI 4057 AIR are composed of two steps:

Austenitization, whose purpose is to dissolve carbon and obtain a hard supersaturated martensite

Tempering, whose purpose is to adjust mechanical for the application (strength / toughness compro-mise). A single or double tempering treatment can be performed depending on the customer specifi-cation.

Austenitization: Austenitization is performed in the range 950°C to 1030°C, for a dwell time of 30 min minimum. Cooling must be fast enough to avoid grain boundary precipitation that would be detrimental for toughness, but not too fast to avoid quench cracking. Oil quenching (with a moderate drasticity fluid) or air cooling can be performed depending on the size of treated parts.

Tempering: Tempering conditions may vary depending on customer’s specifications. Some specifications demand a dou-ble tempering treatment (to relax fresh martensite formed after the 1st tempering) whereas other are requiring a single tempering. Thanks to its low retained austenite content after austenitization, UGI 4057 AIR can indif-ferently be tempered by double or single treatment. For the QT900, the recommended tempering treatment routes are:

640 °C / 4h / AC + 610 °C / 4h / AC (double tempering)

650 °C / 4h / AC (single tempering)

Annealing/softening: Full annealing is impracticable because of long cooling time required. Instead, the following semi-anneal pro-cedure can be employed:

austenitization at rather low temperature to form globular carbides, typically at 800°C for a dwell time of 2 hours followed by furnace cooling until 600°C and air cooling below.

high temperature tempering at 680-700°C for 4 hours followed by air cooling.

Hot forming

UGI 4057 AIR is suitable for forging. It is heated slowly to 850°C, then more quickly to 1150/1180°C for forg-ing between 1180°C and 950°C. Forging must be followed by a stress relief heat treatment at 200°C or sof-tening at between 750 and 850°C or hardening and tempering.

Other

Available products:

Product	Profile	Surface Finishing	Tolerance	Size (mm)
Bar	Round	Hot rolled descaled	k13-k12	22-115
		Turned	k13-k12	22-115
		Smooth Turned Peeled and polished	h11-h10 h9	22-115
		Centerless Ground	h9-h8-h7	5-115
		Cold Drawn	h9	5-21

Welding

Provided certain precautionary measures are taken, UGI 4057 AIR can be subjected to most arc welding or resistance welding techniques in tempered, hardened or softened condition.

To prevent any risk of cold cracking after welding, UGI 4057 AIR must be preheated to between 200 and 300°C and the temperatures between passes maintained at a minimum of 200°C. A tempering heat treat-ment at 650°C is also required after welding.

If a filler metal is needed, a filler wire with a similar composition to that of UGI 4057 AIR is recommended, es-pecially if the mechanical properties of the weld metal have to be the same as that of the base metal. If not, AWS E/ER310 austenitic wire can be used.

Ar + 1 to 3% CO₂ or O₂ shielding gases are recommended for MIG welding. Gas containing H₂ should not be used. Coated electrodes must be oven dried before welding.

UGI® HT286 – Premium Annealed, Cold‑Drawn, and Aged Austenitic Alloy UGI® 4116N Annealed Stainless Steel – Superior Corrosion Resistance & Hardness

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