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Learn 440c stainless steel

Date posted: 12/ 12/ 2016 - The poster: admin

Stainless steel, also known as layer 440c 440c steel is high carbon steel, achieving the highest hardness, resistance and strength of all kinds of stainless steel after heat treatment. These properties make it suitable steel grades for applications such as components of valves and bearings.

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440 stainless steel is classified into 3 layers 440A, 440B and 440c. All three forms of 440 steel grades are commonly used. However, layer 440c is willing than other standard classes.

IMPORTANT ATTRIBUTES

1 / CHEMICAL COMPOSITION

Table 1. Chemical composition ranges of grade 440 stainless steels

Grade C Mn Si P S Cr Mo Ni N
440A min.

max.

0.6

0.75

1

1

0.04

0.03

16

18

0.75

440B min.

max.

0.75

0.95

1

1

0.04

0.03

16

18

0.75

440C min.

max.

0.95

1.20

1

1

0.04

0.03

16

18

0.75

2 / MECHANICAL PROPERTIES

Table 2. Mechanical properties of grade 440C stainless steels

Tempering Temperature (°C) Tensile Strength (MPa) Yield Strength 0.2% Proof (MPa) Elongation (% in 50mm) Hardness Rockwell (HR C) Impact Charpy V (J)
Annealed* 758 448 14 269HB max#
204 2030 1900 4 59 9
260 1960 1830 4 57 9
316 1860 1740 4 56 9
371 1790 1660 4 56 9

* Annealed properties are typical for Condition A of ASTM A276# Brinell hardness is ASTM A276 specified maximum for annealed 440A, B and C.

3 / PHYSICAL PROPERTIES

Table 3. Typical physical properties of grade 440 stainless steels

Grade Density (kg/m3) Elastic Modulus (GPa) Mean Coefficient of Thermal Expansion (μm/m/°C) Thermal Conductivity (W/m.K) Specific Heat
0-100°C (J/kg.K)
Electrical Resistivity (nΩ.m)
0-100°C 0-200°C 0-600°C at 100°C at 500°C
440A/B/C 7650 200 10.1 10.3 11.7 24.2 460 600

5 / SPECIFICATIONS

Table 4. Grade specifications of grade 440 stainless steels

Grade UNS No Old British Euronorm Swedish SS Japanese JIS
BS En No Name
440A S44002 SUS 440A
440B S44003 1.4112 X90CrMoV18 SUS 440B
440C S44004 1.4125 X105CrMo17 SUS 440C

6 / CLASSES MAY SUBSTITUTE

Table 5. Possible alternative grades to 440 stainless steels

Grade Reasons for choosing 440C
440A/B Slightly softer and more corrosion resistant grade needed
440F High machinability required, with same hardness and hardenability as 440C
420 Lower strength and hardness needed than any of the 440 grades
416 Higher machinability required, and the much lower hardness and strength is still adequate

7 / CORROSION RESISTANCE

Grade 440 stainless steel to exhibit excellent light resistance to acid, alkali, food, water and fresh air. A polished surface also helps smooth corrosion-resistant steel grade 440 tempt, passive and hard.

440c steel corrosion-resistant lining similar to the steel type 304.

8 / TEMPERATURE

Grade 440 stainless steel should not be used at lower temperatures related annealing temperature, mechanical property loss caused by the annealing

9 / THERMAL ENGINEERING

Incubate: Grade 440 stainless steel fully annealed at 850-900 ° C, followed by slow furnace cooling cooler at around 600 ° C. Incubate important parts is done at 735-785 ° C, followed by slow furnace cooling.

Sclerosis: Grade 440 stainless steel is heated at 1010 to 1065 ° C, then quenched in air or oil. Oil quenching is usually done for heavy sections. After this process, the steel is tempered at a temperature of 150-370 ° C, to achieve high rigidity and improved mechanical properties.

Incubate at a temperature between 425 and 565 ° C should be avoided as corrosion and impact resistance properties of the layer 440 tend to decrease in this range. In addition, incubation of 590-675 ° C in the class will result in high impact resistance and stiffness loss.

10 / THE WELD

In welding, stainless steel type 440 is pre-heated at 250 ° C, followed by full annealing. Sub-class 420 bar can be used to achieve a high-strength welds. 309 or 310 extra classes rods will, however, give the soft welds with higher ductility.

11 / MACHINERY

Grade 440 stainless steel can be easily processed in composting their status. After machining hardened layers is extremely difficult, or impossible in some cases

12 / APPLICATIONS

Grade 440 stainless steel is used in the following:

  • Bearings
  • perforated tongue
  • High quality blade
  • Surgical Equipment
  • Complain
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