SS 440 Stainless Steel
Stainless steel SS 440A, 440B and 440C are AISI and ASTM standard high carbon and high chromium martensitic stainless steel, SS440 has high strength, good hardness, corrosion resistance, wear resistance and dimensional stability at high temperatures. For technical details of AISI 440 stainless steel, heat treatment and equivalent table, see the tables below.
Datasheet and specifications
The data sheet and specifications of ASTM AISI 440 stainless steel are summarized in the following tables, including chemical composition and properties.
Chemical Composition of SS440 Steel
The following table shows the chemical composition of AISI 440 stainless steel.
| Chemical Composition of Stainless Steel 440.% | |||||||||
| ASTM | Steel | AISI (UNS) | W | Si (≤) | Mn (≤) | P(≤) | S (≤) | Cr | Mo (≤) |
| ASTM A276/A276M | Steel 440 | 440A (S44002) | 0.60-0.75 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0-18.0 | 0.75 |
| 440B (S44003) | 0.75-0.95 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0-18.0 | 0.75 | ||
| 440C (S44004) | 0.95-1.20 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0-18.0 | 0.75 | ||
Properties of 440 Stainless Steel
The properties of SS 440 stainless steel (physical properties, mechanical properties, magnetic properties) are given in the lists below.
Physical properties
| SS440 Physical Properties | |
| Density (g/cm3) | 7.8 |
| Melting point (℃) | 1370-1480 |
| Specific heat capacity, J/(Kg·K) | 460 (0-100℃) |
| Electrical resistivity (μΩ·m) | 0.6 (20℃) |
| Elastic modulus (GPa) | 200 |
| Thermal conductivity (W/m·K) | 24.2 (100℃) |
| Thermal expansion coefficient | 10.2 (0-100℃) |
Mechanical properties
| Mechanical properties | ||||||
| Note (UNS) | Tensile strength (MPa) ≥ | Yield strength, 0.2%, ≥ (MPa) | Elongation by 50 mm (%) ≥ | Area reduction (%) | Toughness | Product and condition |
| 440A (S44002) | 725 | 415 | 20 | 95 HRB | Annealed bar | |
| 1790 | 1650 | 5 | 20 | 51 CDH | Bars tempered at 315°C | |
| ≤ 965 | Annealed wire, cold finished | |||||
| 440B (S44003) | 740 | 425 | 18 | 96 HRB | Annealed bar | |
| 1930 | 1860 | 3 | 15 | 55 HRC | Bars tempered at 315°C | |
| ≤ 965 | Annealed wire, cold finished | |||||
| 440C (S44004) | 760 | 450 | 14 | 97 HRB | Annealed bar | |
| 1970 | 1900 | two | 10 | 57 HRC | Bars tempered at 315°C | |
| ≤ 965 | Annealed wire, cold finished | |||||
Heat resistance SS440
AISI 440 has good resistance to oxidation in intermittent use below 815 °C and continuous use up to 760 °C in air.
SS440 heat treatment
SS440 heat treatment including annealing, quenching, tempering and stress relieving, etc.
girdling
Subcritical annealing temperature range: 675-760 ℃ (1250-1400 ℉)
Complete annealing: insulation at 845-900°C (1550-1650℉) until complete immersion, then oven cooling to 790°C, continued cooling to 595°C at a cooling rate of 15-25°C/h, then air cooled to room temperature.
Isothermal Annealing: heat treatment at 845-900 °C, maintained at 690 °C for 4 hours.
SS440 tempering
Heat to 1010-1065 °C and quench in air or oil. To ensure maximum dimensional stability, cold treatment must be carried out immediately after cooling to room temperature.
Tempering and Hardness
For 440A and 440B stainless steel, 150°C – 370°C, and can achieve hardness HRC 49-57 for 440A, 53-59 for 440B steel.
For 440C stainless steel, tempering temperature and corresponding HRC hardness as follows
- Max 160 °C, ≥ 60 HRC
- Max 190 °C, ≥ 58 HRC
- Max 230 °C, ≥ 57 HRC
- Max 355°C, 52-56 HRC
Forging
Typical forging temperature range for 440A, 440B and 440C stainless steel.
- 440A: 925-1200℃
- 440B: 925-1175℃
- 440C: 925-1150℃
Hardening
440 stainless steel can be hardened and tempered in the same way as alloy steel.
Machinability
440 steel, especially 440C, is difficult to process due to its high annealing hardness and abrasive chromium carbide.
Welding
Welding 440 steel is not recommended due to the high carbon content, it is extremely easy to break, and metal fillers are not readily available.
AISI 440 Steel Applications
AISI 440 steel is used in the manufacture of bearing parts that work in corrosive environments, and can also be used in the manufacture of high quality tools (scalpels, medical scissors and blades, surgical and dental instruments), molds and matrices, springs, cutlery , valves and valve components. , cams, gears, shafts, ball bearings, nozzles and measuring tools.
Equivalence
AISI 440 steel equivalent to US ASTM AISI, European EN (Germany DIN, Great Britain BS, France NF…), ISO, Asian Japanese JIS and China GB standards. (For reference)
| ASTM 440C Stainless Steel Equivalent Grades | |||||||||||||||
| USA | European Union | Germany | UK | France | ISO | Japan | China | ||||||||
| Standard | Note | Standard | Steel Name (Steel Number) | Standard | Note | Standard | Note | Standard | Note | Standard | Note | Standard | Note | Standard | Note |
| AISI, ASTM A276/A276M |
440°C | EN 10088-3 | X105CrMo17 (1.4125) |
DIN EN 10088-3 | X105CrMo17 (1.4125) |
EN 10088-3 | X105CrMo17 (1.4125) |
NF EN 10088-3 | X105CrMo17 (1.4125) |
ISO 683-17 | X108CrMo17 | JIS G4303 | SUS 440C | GB/T 1220 | 9Cr18Mo |
Related material: SS 304, AISI 316 stainless steel, SAE 4140 steel
