Martensitic stainless steel

• Overview

  Martensitic stainless steel is a kind of stainless steel whose mechanical properties can be adjusted by heat treatment (quenching and tempering). Generally speaking, it is a kind of hardened stainless steel. High hardness can be obtained after quenching treatment, different tempering temperature will result in different strength and toughness combination.

  Standard martensitic stainless steels are 410, 414, 416, 416(Se), 420, 431, 440A, 440B and 440C, which are magnetic. The corrosion resistance of these steels comes from "chromium", which ranges from 11.5 to 18 per cent. Steels with higher chromium content require higher carbon content to ensure the formation of martensite during heat treatment. The above three types of 440 stainless steel are rarely considered for applications requiring welding, and the filler metal for 440 is not readily available。

• Properties

  Martensitic stainless steel has high strength and corrosion resistance.

  Martensitic stainless steel, like tempered steel, can be quenched, tempered and annealed. Its mechanical properties are similar to those of tempered steel: as hardness increases, tensile strength and yield strength increase, while elongation, section shrinkage and impact energy decrease.

  The corrosion resistance of martensitic stainless steel mainly depends on the chromium content, and the carbon in steel indirectly affects the corrosion resistance of steel because it forms stable chromium carbide with chromium. Therefore, in 13%Cr steel, the lower the carbon content, the higher the corrosion resistance.

• Classification

  According to the difference of chemical composition, martensitic stainless steel can be divided into two types, Cr series and Cr-Ni series.

  According to the different structure and strengthening mechanism, it can be divided into martensitic stainless steel, martensitic precipitation hardening stainless steel, half austenitic (or half martensitic) precipitation hardening stainless steel and martensitic aging stainless steel.

• Common grade

  S40900 (TP409, 0Cr13, 06Cr13)

  S41000 (TP410, 1Cr13, 12Cr13 )

  S42020 (2Cr13, 20Cr13)

  S42030 (3Cr13, 30Cr13)

  S42040 (4Cr13, 40Cr13)

  S44002 (440A, 7Cr17, 68Cr17)

  S44003 (440B, 8Cr17, 85Cr17)

  S44004 (440C, 11Cr17, 108Cr17)

• Application

  It is mainly used in steam turbine blades, tableware, surgical instruments, etc.