Stainless Steel – Grade 440B (UNS S44003)

Topics Covered

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

Introduction

Stainless steels are high-alloy steels with good corrosion resistance because of large amounts of chromium present in them. About 10% of chromium is present in most stainless steels.

Stainless steels are available in three different groups based on their crystalline structure. These groups include martensitic, austenitic and ferritic. The combination of martensitic and ferritic steels forms a fourth group of stainless steels known as precipitation-hardened steels.

Grade 440B stainless steel is a high carbon martensitic stainless steel containing good strength, moderate corrosion resistance and ability to obtain and maintain wear resistance and excellent resistance.

The following datasheet provides an overview of grade 440B stainless steel.

Chemical Composition

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

Element Content (%)
Iron, Fe 80
Chromium, Cr 16.0-18.0
Manganese, Mn 1.0
Silicon, Si 1.0
Carbon, C 0.75-0.95
Molybdenum, Mo 0.75
Phosphorous, P 0.040
Sulfur, S 0.030

Physical Properties

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

Properties Metric Imperial
Density 7.74 g/cm3 0.280 lb/in³
Melting point 1482°C 2700°F

Mechanical Properties

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

Properties Metric Imperial
Elastic modulus 190-210 GPa 27557-30458 ksi
Poisson's ratio 0.27-0.30 0.27-0.30

Thermal Properties

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

Properties Metric Imperial
Thermal conductivity (for stainless 410A0) 24.2 W/mK 168 BTU in/hr.ft².°F

Other Designations

Equivalent materials to grade 440B stainless steel are given in the table below.

AISI 440B ASTM A276 ASTM A314 ASTM A473
DIN 1.4112 QQ S763 FED QQ-S-763 MIL SPEC MIL-S-862
SAE J405 (51440B) SAE 51440B ASTM A580

Fabrication and Heat Treatment

Tempering

Grade 440B stainless steel is tempered at 148°C (300°F) to obtain maximum properties and the maximum hardness that can be obtained is RC 58.

Annealing

Grade 440B stainless steel is annealed at 843-871°C (1550-1600°F) and then cooled very slowly in a furnace.

Cold Working

Grade 440B stainless steel can be slightly cold worked by common cold working methods.

Welding

Welding is not generally recommended for grade 440B stainless steel as it tends to harden in air. If this steel grade is welded the recommended temperature is 260°C (500°F) and for the post weld treatment the recommended temperature is 732-760°C (1350-1400°F). The post weld treatment should take place for 6 h and then the material should be cooled slowly in a furnace to avoid cracking. Similar high heat inputs and filler metal should be used during operations.

Machinability

Grade 440B stainless steel is best machined in the annealed condition. Chip breakers are used to handle tough, stringy chips of grade 440B stainless steel. Ceramic or carbide tooling is best suited for this grade 440B stainless steel.

Hot Working

Hot working for grade 440B stainless steel takes place by pre-heating the steel to 760°C (1400°F) which is then followed by slowly increasing the temperature range to 1038-1204°C (1900-2200°F). After the hot working process, the material is then cooled slowly at room temperature followed by complete annealing.

Hardening

Grade 440B stainless steel is heated at 760°C (1400°F), soaked at 1010°C (1850°F) and finally cooled in oil or air.

Applications

Grade 440B stainless steel is used in measuring instruments, gage blocks, cutlery, knives, dies, molds, ball bearings and valve components.

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