1.4057 | AISI 431 Stainless Steel

1.4057 steel is martensitic stainless steel, corresponding to the European standard X17CrNi16-2 as per EN10088-3.

As a heat-treatable stainless steel, the addition of nickel gives 1.4057 steel a balance of higher strength, excellent toughness, and corrosion resistance.

With its superior overall performance, 1.4057 has become the preferred upgrade for 12% chromium stainless steel 410 and 420,widely used in industries such as machinery, automobiles, aviation, and medical.

1.4057 STEEL CHEMICAL COMPOSITION

Grade	C	Si	Mn	P	S	Cr	Ni
1.4057	0.12-0.22	≤1.0	≤1.0	≤0.04	≤0.03	15.0-17.0	1.25-2.5
431	≤0.2	≤1.0	≤1.0	≤0.04	≤0.03	15.0-17.0	1.25-2.5

1.4057 STEEL EQUIVALENT GRADE

Europe	USA	China	Japan
X17CrNi16-2	431	14Cr17Ni2	SUS431

1.4057 STEEL PHYSICAL PROPERTY

Density, g/cm3	7.75
Specific heat capacity，20℃,kj/(kg.k)	0.46
Thermal conductivity,20℃ W/(m.K)	20.2
Linear expansion coefficient,10^-6/k	0~100℃	0~500℃
	10.3	12.4
Resistivity（20℃),Ω.mm2/m	0.72
Longitudinal modulus of elasticity （20℃)，kN/mm2	193
Magnetic	Magnetic

1.4057 STEEL FORGING

1.4057 steel has poor thermal conductivity and low low-temperature plasticity, so the temperature range and cooling process must be strictly controlled during forging.

Preheating	Initial forging temperature	Final forging temperature	Forging ratio
800-850°C	1100-1150°C	≥900℃	≥4:1

1.4057 is a martensitic steel, which is highly prone to cracking. Therefore, slow cooling is essential. Annealing immediately after forging is the recommended method.

1.4057 STEEL HEAT TREATMENT

1.4057 steel Pretreatment: Softening Annealing

The purpose of softening annealing of 1.4057 steel is to reduce the hardness to a machinable level, eliminate forging/rolling internal stress, homogenize the microstructure, and prepare the microstructure for subsequent heat treatment.

Annealing temperature	Cooling method	Hardness	Microstructure
700-750 ℃	Furnace cooling	≤285HBW	Pearlite + Ferrite

1.4057 steel Final Heat Treatment: Quenching & Tempering

1.4057 is a martensitic stainless steel that can be strengthened by quenching and tempering. Its core feature is that its performance can be flexibly matched between “high strength” and “high toughness” by adjusting the tempering temperature.

The purpose of quenching 1.4057 steel is to obtain a martensitic structure, thereby significantly improving its strength and hardness.

Quenching temperature	Cooling method	Hardness	Microstructure
950-1050 ℃	Oil cooling	48-52HRC	Martensite + Austenite (small amount)

1.4057 steel must be tempered immediately after quenching! Tempering is the core process that determines the final performance, achieving a balance between strength and toughness through temperature adjustment.

1.4057 steel Tempering temperature vs Hardness

Tempering temperature	Hardness	Performance characteristics
200-300 ℃	HRC 45-50	High strength, low toughness
600-650 ℃	HRC 30-35	Good balance between strength and toughness
650-800 ℃	HRC 25-30	Excellent toughness

1.4057 steel Mechanical properties under different tempering processes

	Tempering process	Tensile strength Rm	Yield strength Rp0.2	Elongation A	Hardness
+QT800	Double tempering First:750-800℃ Second:650-700℃	800-950 MPa	≥600 MPa	≥14%	HRC 25-30
+QT900	Single tempering 600-650℃	900-1050 MPa	≥700 MPa	≥12%	HRC 30-35