APX4, X4CrNiMo16-5-1, 1.4418, Z6CND16-05-01, FE-PM3504, Z8CND17-04, Z 8 CND 17-04, Z8CND17.04, Z 8 CND 17.04, X164M, BMS H-10, S165M, SS2387, SS 2387, 248SV, 08Х17Н5М3, Х17Н5М3, 08Ch17N5M3, Ch17N5M3, 08Kh17N5M3, Kh17N5M3, H17N5M3, 08H17N5M3">

APX4 Martensitic stainless steel


Martensitic stainless steel APX4

APX4 Martensitic stainless steel - Introduction and Application

APX4 is characterised by its very good resistance to corrosion in aggressive media coupled with very good mechanical and impact properties, is one of the martensitic grades, APX4 is comparable to APX4 acc. to SEW400 : 1991-02. showing sufficient corrosion resistance, good strength properties and high hardness with reduced carbon content, good corrosion resistance and cryogenic toughness up to -200 °C. The steel has high corrosion resistance especially to water.the steel has very good strength and corrosion resistance of welded joints, resistance to fatigue, very good parameters in low temperature environments, and corrosion resistance comparable to austenitic steels 18-8. In addition, it is characterized by good weldability.this material is a martensitic stainless steel for machine engineering, for pumps, fittings, compressors as well as for shipbuilding, The material supplied mainly in the form of bars is used for the production of valves, turbine subassemblies, nuts and bolts, shafts, pins, pistons, spindles, crankshafts, agitators in the chemical, energy, marine, shipbuilding, aviation/cryogenic industries. 

Low-carbon stainless steel APX4 is a material very susceptible to heat treatment, which is used in many industries: marine, chemical, energy, shipbuilding, cryogenic.

Stainless steel APX4 is mainly used in the energy industry. It was from her are built all kinds of valves, turbine components, nuts, bolts, shafts, pins, Pistons, pins, spindles, crankshafts. Stainless steel is also used in APX4 aerospace, maritime, cryogenic. In addition, they are produced with the bolts, pump, tool holders.

This low-carbon stainless steel grade APX4 is one of the best martensitic steel grades, which is characterized by very high mechanical properties and resistance to corrosion. In addition, it has very good strength properties and a high degree of hardness with a low carbon content in the composition. High strength and corrosion resistance influence the ease of processing and make it a good welding material. The tensile strength of this steel grade ranges from 760 to 960 MPa, the yield strength is 550 MPa. The elongation is 14 % and the modulus of elasticity is E 200 GPa. In terms of physical properties of steel, it is worth remembering that the density is 7.70 g*cm3.

First of all, martensitic steel with low carbon content is many technological processes during metal forming and heat. The process of forging of stainless steel is possible at temperatures between 1150-900 ° C, roll forming starts at temperatures between 1150-900 ° C, annealing is best carried out at temperatures between 600-650 ° C, quenching of steel should be held from 950-1050 ° C, and tempering at temperatures between 550-620 ° C. In addition, the steel from this species is adapted to work in low concentrations and temperatures. Does not change its properties when working in moderately aggressive acids: acetic acid, citric acid, hydrochloric solution, pyrogal, tannin, stearic and compounds sulfur and nitrates. The individual needs of business grade of stainless 1.4418 is supplied in the form of rods, which then are used for the production of a variety of items.

EN 10088-2: 2005 Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion resisting steels for general purposes
EN 10088-3: 2005 Stainless steels. Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion resisting steels for general purposes
EN 10028-7: 2007 Flat products made of steels for pressure purposes. Stainless steels
EN 10272: 2007 Stainless steel bars for pressure purposes
EN 10250-4: 2000 Open steel die forgings for general engineering purposes. Stainless steels
EN 10088-1: 2005 Stainless steels. List of stainless steels
EN 10088-5: 2009 Stainless steels. Technical delivery conditions for bars, rods, wire, sections and bright products of corrosion resisting steels for construction purposes
EN 10088-4: 2009 Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion resisting steels for construction purposes



Melted process

AOD+ESR


APX4 Martensitic stainless steel - Chemical composition WT %

GradesChemical Composition WT %
CMnSiPSCrNiMoN
APX4Max 0.6Max 1.5Max 0.7Max 0.04Max 0.0315.0 - 17.04.0 - 6.00.8 - 1.5Min 0.02
Z6CND16-05-01Max 0.06Max 1.0Max 1.0Max 0.040Max 0.02515.0 - 17.03.5 - 5.50.80 - 1.25-
Z8CND17-040.050.75---16.05.01.00.03
S165M, SS 2387Max 0.05Max 1.5Max 1.0Max 0.045Max 0.03015.0 - 17.04.0 - 6.00.8 - 1.5-

Mechanical Property of APX4 Martensitic stainless steel

Annealed condition +A

  • for dimensions Min  16mm 
    • Tensile strength, Rm: <1100 MPa
    • Hardness, HB: <320
  • for dimensions Min  16mm 
    • Tensile strength, Rm: <1150 MPa
    • Hardness, HB: <380

Heat-treated condition +QT760 for bars

  • Tensile strength, Rm: 760 - 960 MPa
  • The yield point, Re: Min  550 MPa
  • Elongation, A:Min  16%
  • Impact resistance for dimensions KV20℃: Min 70J

Heat-treated condition +QT900 for bars

  • Tensile strength, Rm: 900 - 1150 MPa
  • The yield point, Re: Min  700 MPa
  • Elongation, A:Min  10%
  • Impact resistance for dimensions KV20℃: Min 60J

Heat-treated condition +QT840 for bars

  • Tensile strength, Rm: 840 - 1100 MPa
  • The yield point, Re: Min  660 MPa
  • Elongation, A:Min  14%
  • Impact resistance for dimensions KV20℃: Min 55J

Other mechanical and physical properties

  • Modulus of elasticity, E = 200 GPa
  • Thermal capacity, c-1
  • Thermal conductivity, λ = 15 W * m-1
  • Specific resistance, Ω: 0,8 mkOhm * m

Mechanical properties at elevated temperatures of X4CrNiMo16-5-1, 1.4418, Z8CND17-04

PropertiesTemperature
100℃150℃200℃250℃300℃350℃400℃
p0,2 (MPa)+QT760Min 520Min 510Min 500Min 490Min 480--
+QT900Min 660Min 640Min 620Min 600Min 580--
+QT840Min 660Min 640Min 620Min 600Min 580--
Modulus of elasticity, E (GPa)195-185-175-170
-1)10,3-10,8-11,2-11,6

Mechanical properties at elevated temperatures of X4CrNiMo16-5-1, 1.4418, Z8CND17-04

PropertiesTemperature
100℃150℃200℃250℃300℃350℃400℃
p0,2 (MPa)+QT760Min 520Min 510Min 500Min 490Min 480--
+QT900Min 660Min 640Min 620Min 600Min 580--
+QT840Min 660Min 640Min 620Min 600Min 580--
Modulus of elasticity, E (GPa)195-185-175-170
-110,3-10,8-11,2-11,6



Physical Property of APX4 Martensitic stainless steel

density (kg/dm3)  7.70

electrical resistivity at 20 °C (Ω mm2/m)  0.70

magnetizability  yes

thermal conductivity at 20 °C (W/m K)  15

specific heat capacity at 20 °C (J/kg K)  430

thermal expansion (K-1) :

  • 20 – 100 °C: 10.8 x 10-6
  • 20 – 200 °C: 10.8 x 10-6
  • 20 – 300 °C: 11.2 x 10-6
  • 20 – 400 °C: 11.6 x 10-6

Heat Treatment of APX4 Martensitic stainless steel

  • Delivery condition + A- Annealing at a temperature of 600 - 650 ℃ with cooling in air or with a furnace
  • Delivery condition +QT760- Hardening at 950 - 1050 ℃ with cooling in oil or air, tempering at 590 - 620 ℃
  • Delivery condition +QT900- Hardening at 950 - 1050 ℃ with cooling in oil or air, tempering at 550 - 620 ℃
  • Delivery condition +QT840- Hardening at 900 - 1000 ℃ with cooling in oil or air, tempering in the range of 570 - 650 ℃

Welding of APX4 Martensitic stainless steel

Good weldability, X4CrNiMo16-5-1, 1.4418, Z8CND17-04 is readily weldable using all standard welding techniques. Care must however be taken to ensure that hydrogen or carbon containing gasses are not used when welding under shielded gas. Pre-heating of the work piece to a temperature between 100°C and 200°C is recommended. After welding, the weldment should either be annealed or tempered, as described before. If a filler material is required, then either a matching filler or Novonit® 4430 should be used.


Machining of APX4 Martensitic stainless steel

The machinability of this grade of stainless steel is directly related to its hardness. X4CrNiMo16-5-1, 1.4418, Z8CND17-04 machines similar to carbon steels of the same hardness. Although it must be realised that the machining parameters will vary depending on the heat treated condition and hardness of the steel


Equivalent grades of APX4 Martensitic stainless steel

APX4, X4CrNiMo16-5-1, 1.4418, Z6CND16-05-01, FE-PM3504, Z8CND17-04, Z 8 CND 17-04, Z8CND17.04, Z 8 CND 17.04, X164M, BMS H-10, S165M, SS2387, SS 2387, 248SV, 08Х17Н5М3, Х17Н5М3, 08Ch17N5M3, Ch17N5M3, 08Kh17N5M3, Kh17N5M3, H17N5M3, 08H17N5M3

APX4 Martensitic stainless steel Martensitic & Precipitation hardened stainless steel stock list

Grade Shape Dimensionmm Qty.kg
APX4 ESR Ingot φ360 1001
APX4 Round bar Φ16 688
APX4 Round bar Φ20 2331
APX4 Square bar 60x60xL 640