Martenistic & Precipitation Hardening

Martensitic and precipitation hardening grades


Martensitic and precipitation hardening stainless steels are heat treatable and can therefore provide hardness and strength in a wide range. Allowing to workability they are supplied in solution annealed condition. The downstream manufacturer performs final heat treatment to meet the mechanical properties required.


Martensitic grades are basically Fe-Cr alloys with a higher carbon content than ferritics which enables them to harden on cooling in air, oil or water. Depending on grade and intended use, ductility is improved by tempering. Martensitic grades are applied e.g. for cutting utensils, surgical and dental instruments, fasteners, springs, ball bearings and press plates. They are also popular in the petrochemical industry, e.g. for steam and gas turbines.

Precipitation hardening grades have higher alloying contents than martensitic grades. They contain nickel, and in order to achieve hardening by aging additions of copper, aluminium, titanium, niobium and molybdenum. Depending on chemical composition their microstructure after final heat treatment is austenitic, semi-austenitic or martensitic. Applications for our precipitation hardening grades are for instance retaining rings, spring holders, springs, chains, valves, gears, aircraft parts, pressure vessels and seals.

Our martensitic and precipitation hardening stainless steels are available in the grades listed below (further grades on request) and in many, product forms and surface finishes

 

Grades :

Maternistic grades

Maternistic EN ASTM
4006 1.4006 410
4005 1.4005 416
4021 1.4021 420
4031 1.4031 420
4034 1.4034 420
4028 1.4028 420
4313 1.4313 -
4116 1.4116 -
4110 1.4110 -
4112 1.4112 -

 

Percipitation Hardening grades

  EN ASTM
4542 1.4542 630
4568 1.4568 631
4574 1.4574 632

 

Properties

High strength and hardness distinguish martensitic stainless steels from the other stainless steel families. After austenitizing cooling is performed in air, water or oil, depending on steel grade. If the intended application requires a high level of hardness (e.g. knives, HRC55), only stress relief annealing will be performed. Normally martensitic stainless steels are tempered in order to acquire useful mechanical properties, i.e. a certain level of toughness (A5 ≥ 15 %).

Nickel-martensitic steels are superior to traditional martensitic grades regarding strength in combination with toughness. Their microstructure contains stable austenite after hardening and tempering which accounts for good toughness without drawbacks concerning corrosion resistance.

Precipitation hardening stainless steels provide remarkable levels of high strength and hardness in a very wide range. With the exception of the martensitic alloys (e.g. 1.4542) cold formability is satisfactory

Weldability

Traditional martensitic steels with a carbon content > 0.20 % are difficult to weld; assistance is advised. The hardenable high-carbon grades are not suitable for welding.

Low-carbon nickel-martensitic grades have relatively good weldability.

Welding of precipitation hardened grades is possible, but depending on grade some limitations might have to be regarded

Corrosion Resistant

​Corrosion resistance of martensitic stainless steels may vary considerably depending on chemical composition (C, Cr, Mo), surface finish and especially heat treatment. Smooth polished surfaces experience higher resistance than rougher finishes. In terms of heat treatment the hardened condition is more favourable, since the elements promoting corrosion resistance are in solution and therewith effective. Tempering may lead to carbide precipitation which impairs corrosion resistance. This is always the case for traditional martensitic grades, whereas nickel-martensitic grades with max 0.06 % carbon and 3-6 % nickel (e.g. 1.4313 and 1.4418) do not sacrifice corrosion resistance by tempering.

Corrosion resistance of precipitation hardening steels is higher compared with heat treatable martensitic stainless steels ranking between ferritic Cr  and austenitic CrNi steels.

Forms

You can get martensitic and precipitation hardening grades in a variety of forms:

  • Coil and sheet
  • Thin strip
  • Precision strip
  • Quarto plate

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