1.4542 - 17-4PH – X5CrNiCuNb16-4 – AISI / SAE 630


Alloy 1.4542 or 17-4PH is a structurally hardened martensitic stainless steel that combines a hardness of around 43 HRC with very good corrosion resistance. This grade has a hardening peak at 480°C, making it easy to carry out ageing after machining on a condition initially in solution (condition A). The grade is also available pre-treated and/or as an aerospace-grade remelted version.

Stainless has several sources in stock, as well as different product formats and conditions, to meet your processing requirements. This product can also be made to measure or cut into blanks by our service centres.

Main applications

Thanks to its good resistance to corrosion, its good hardness in the treated state (43HRC) and its resilience, the grade is used in particular in the manufacture of instruments for the medical sector, general mechanics, the food industry and the automotive industry.


The manufacturing processes combined with the transformation processes produce a homogeneous microstructure. In the treated state, the microstructure consists of martensite and nanometric intermetallic precipitates (Ni3Cu) that germinate during ageing.

17-4PH - 1.4542 - ASTM F899



The grade can be hot forged in the 950/1200°C temperature range. Resolving will be necessary to achieve maximum hardness.

The grade can be welded using most processes. Welding should preferably be carried out before ageing to avoid embrittling the heat-affected zone.

Typical heat treatments

For a target hardness ≥ 40HRC
– Heating 1030/1050°C
– Oil quench
– H900 ageing (480°C /2h)

Volume shrinkage of up to approximately 0.07% is to be expected during ageing.

Corrosion resistance

The grade is highly resistant to corrosion and is one of the best martensitic stainless steels. The microstructure contains little or no chromium carbides, making it highly insensitive to intergranular corrosion.

Standard Sizes

Round or flat bars, annealed (Condition A or AT) or pre-treated – Surface hardened or ground depending on diameter
Flat bars made to measure in the annealed condition (consult us)
Other formats: forged blocks, sheet, strip, powder.