Stainless Steel Pipe Fittings

Martensitic Stainless Steel By yaang.com

Written by
Martensitic Stainless Steel By yaang.com

Martensitic stainless steel have the highest strength but also the lowest corrosion resistance of the stainless steel. Martensitic steels with high carbon contents are used for tool steel. Due to their high strength in combination with somecorrosion resistance, martensitic steels are suitable for applications where the material is subjected to both corrosion and wear. An example is in hydroelectric turbines. 
Martensitic grades of stainless steel were developed in order to provide a group of stainless alloys that would be corrosion resistant and hardenable by heat treating. The martensitic grades are straight chromium steels containing no nickel. They are magnetic and can be hardened by heat treating. The martensitic grades are mainly used where hardness, strength, and wear resistance are required. 

Martensitic stainless steel has a relatively high carbon content (0.1% – 1.2%) compared to other stainless steel. The martensitic steels are plain chromium steel containing between 12% and 18% chromium, can be heat treated to obtain high strength with good ductility. Martensitic stainless steel has very high hardenability. When only limited corrosion resistance or resistance to moderately elevated temperature scaling is required, can be used in the annealed condition, but its highest corrosion resistance is attained in the hardened and stress relieving (low temperature tempered) condition.

Type 410

Basic martensitic grade, containing the lowest alloy content of the three basic stainless steels (304, 430, and 410). Low cost, general purpose, heat treatable stainless steel. Used widely where corrosion is not severe (air, water, some chemicals, and food acids. Typical applications include highly stressed parts needing the combination of strength and corrosion resistance such as fasteners.

Type 410S

Contains lower carbon than Type 410, offers improved weldability but lower hardenability. Type 410S is a general purpose corrosion and heat resisting chromium steel recommended for corrosion resisting applications.

Type 414

Has nickel added (2%) for improved corrosion resistance. Typical applications include springs and cutlery.

Type 416

Contains added phosphorus and sulfur for improved machinability. Typical applications include screw machine parts.

Type 420

Contains increased carbon to improve mechanical properties. Typical applications include surgical instruments.

Type 431

Contains increased chromium for greater corrosion resistance and good mechanical properties. Typical applications include high strength parts such as valves and pumps.

Type 440

Further increases chromium and carbon to improve toughness and corrosion resistance. Typical applications include instruments.

The major alloying addition in martensitic stainless steel is chromium in the range of 11 to 17%. The carbon levels can vary from 0.10 to 0.65% in these alloys. This radically changes the behavior of the martensitic alloys relative to the ferritic 400 Series alloys. The high carbon enables the material to be hardened by heating to a high temperature, followed by rapid cooling (quenching). Martensitic types offer a good combination of corrosion resistance and superior mechanical properties, as produced by heat treatment to develop maximum hardness, strength and resistance to abrasion and erosion. The martensitic grades are usually sold in the soft state. This allows the customers to cut or form the parts before they are thermally hardened. End uses include cutlery, scissors, surgical instruments, wear plates, garbage disposal shredder lugs, and industrial knives. The AL 403 alloy is used to make vanes for steam turbines. 

Stainless Steel – Martensitic
Alloy
(UNS Designation)
End Use Composition
nominal wt%
Specifications Density
lb/in3 (g/cm3)
Tensile
Strength
ksi. (MPa)
0.2% Yield
Strength
ksi. (MPa)
Elong-
ation %
Hardness
AL 403
S40300
Turbine blades, banding, strapping and hose clamps C 0.15 max, Mn 1.0 max, Si 0.5 max, Cr 11.5-13.0, Ni 0.6 max, P 0.04 max, S 0.03 max, Fe Balance ASTM A176 AMS QQ5763 0.280
(7.75)
70 min
(485 min)
30 min
(205 min)
25 min 96 Rockwell B max

410 
S41000
Cutlery, dental and surgical instruments, nozzles, valve parts, hardened steel balls and seats for oil well pumps, separating screens and strainers, springs, shears, and wear surfaces C 0.08-0.15, Mn 1.0 max, P 0.04 max, S 0.03, Si 1.0, Cr 11.5-13.5, Ni 0.75 max, Fe Balance ASTM A240 0.276
(7.65)
65 min
(450 min)
30 min
(205 min)
20 min 96RockwellB max (Annealed) 38-45 RC (Hardened)

416 
S41600
Cutlery, dental & surgical instruments C 0.15 max, Mn 1.25 max, Si 1.0 max, Cr 12.0-14.0, P 0.06 max, S 0.15 min, Mo 0.60 max, Fe Balance ASTM A895 ASTM A194 AMMS 55610 SAE J405 0.280
(7.74)
75-90
(517-621)
40-50
(276-345)
15-30 38-45 Rc (Hardened)

AL 418 SPL
S41800
Engine braces, turbine exhaust components, exhaust struts, stiffeners, ducts C 0.15-0.20, Cr 12.0-14.0, Mn 0.50 max, Ni 1.8-2.2, P 0.04 max, S 0.03 max, Si 0.50 max, W 2.5-3.5, Fe Balance AMS 5508 0.284
(7.87)
130
(900)
105
(725)
20 25-50 Rockwell C (Hardened)

420
S42000
Cutlery, Dental and surgical instruments, nozzles, valve parts, hardened steel balls and seats for oil well pumps, separating screens and strainers, springs, shears, and wear surfaces C 0.15 min, Mn 1.0 max, Si 1.0 max, Cr 12.0-14.0, Ni 0.75 max, Mo 0.5 max S 0.03 max, P 0.04 max, Fe Balance ASTM A176 0.280
(7.74)
85
(586)
45
(310)
29 53-57 Rockwell C (Hardened)

440A
S44002
Cutlery, dental and surgical instruments, nozzles, valve parts, hardened steel balls and seats fro oil well pumps, separating screens and strainers, springs, shears, and wear surfaces C 0.60-0.75, Mn 1.0 max, Si 1.0 max, Cr 16.0-18.0, Mo 0.75 max, S 0.03 max, P 0.04 max, Fe Balance ASTM A276 0.279
(7.72)
104
(717)
62
(427)
20 57-60 Rockwell C (Hardened)

440C
S44004
Bearings, valve parts, cutlery and industrial knives C 0.95-1.20, Mn 1.0 max, Si 1.0 max, Cr 16.0-18.0, Mo 0.75 max, S 0.03 max, P 0.04 max, Fe Balance ASTM A276 AMS 5630 QQ-S-763 0.277
(7.68)
110
(760)
65
(450)
15 58-61 Rockwell C (Hardened)

Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)

Article Categories:
Stainless Steel

Leave a Comment

Your email address will not be published. Required fields are marked *