Stainless Steel – Grade 440C (UNS S44004)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Welding
Hot Working
Cold Working
Annealing
Tempering
Hardening
Applications

Introduction

Stainless steels are high-alloy steels which have high corrosion resistance compared to other steels due to the presence of large amounts of chromium. Based on their crystalline structure, they are divided into three types such as ferritic, austenitic, and martensitic steels. Another group of stainless steels are precipitation-hardened steels. They are a combination of martensitic and austenitic steels.

Grade 440C stainless steel is a high carbon martensitic stainless steel. It has high strength, moderate corrosion resistance, and good hardness and wear resistance.

The following datasheet gives an overview of grade 440C stainless steel.

Chemical Composition

The chemical composition of grade 440C stainless steel is outlined in the following table.

Element Content (%)
Iron, Fe 79.15
Chromium, Cr 17
Carbon, C 1.1
Manganese, Mn 1
Silicon, Si 1
Molybdenum, Mo 0.75

Physical Properties

The following table shows the physical properties of grade 440C stainless steel.

Properties Metric Imperial
Density 7.80 cm³ 0.282 lb/in³
Melting point 1483°C 2700°F

Mechanical Properties

The mechanical properties of grade 440C stainless steel are displayed in the following table.

Properties Metric Imperial
Tensile strength 760-1970 MPa 110000-286000 psi
Yield strength (@ strain 0.200%) 450-1900 MPa 65300-276000 psi
Bulk modulus 166 GPa 24100 ksi
Shear modulus 83.9 GPa 12200 ksi
Elastic modulus 200 GPa 29008 ksi
Poisson's ratio 0.27-0.30 0.27-0.30
Elongation at break 2-14 % 2-14 %
Hardness, Rockwell B (converted from Brinell hardness) 97 97

Thermal Properties

The thermal properties of grade 440C stainless steel are given in the following table.

Properties Metric Imperial
Thermal expansion co-efficient 10.2 µm/m°C 5.67 µin/in°F
Thermal conductivity 24.2 W/mK 168 BTU in/hr.ft².°F

Other Designations

Other designations that are equivalent to grade 440C stainless steel include:

  • AMS 5618
  • AMS 5630
  • AMS 5880
  • ASTM A276
  • ASTM A314
  • ASTM A473
  • ASTM A493
  • ASTM A580
  • DIN 1.4125
  • QQ S763
  • MIL-S-862
  • SAE 51440C
  • SAE J405 (51440C)

Fabrication and Heat Treatment

Machinability

Grade 440C stainless steel can be machined in the annealed condition. Chip breakers can be used to handle tough and stringy chips. Carbide or ceramic tooling is preferred for this alloy.

Welding

Grade 440C stainless steel is not welded because it can be easily air hardened. To weld this alloy, it should be preheated to 260°C (500°F) and post weld treated at 732-760°C (1350-1400°F) for 6 h followed by slowly cooling in the furnace to prevent cracking.

Hot Working

Grade 440C stainless steel is pre-heated at 760°C (1400°F). Temperature can be increased up to 1038-1204°C (1900-2200°F). It should not be heated below 927°C (1700°F). It is then slowly cooled at room temperature and fully annealed.

Cold Working

Grade 440C stainless steel is slightly cold workable using common practices.

Annealing

Grade 440C stainless steel is annealed at 843-871°C (1550-1600°F) followed by slowly cooling in the furnace.

Tempering

Grade 440C stainless steel can be tempered by soaking at 148°C (300°F).

Hardening

Grade 440C stainless steel can be hardened by heating at 760°C (1400°F). Temperature can be increased up to 1010°C (1850°F) followed by cooling in air or oil.

Applications

Grade 440C stainless steel is used in the following applications:

  • Gage blocks
  • Cutlery
  • Ball bearings and races
  • Molds and dies
  • Knives
  • Valve components
  • Measuring instruments


Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit