High Grade Stainless Steel

무공해건강냄비 2013. 8. 19. 10:40

 

316L 스텐레스 재질은 기존 304L 스텐레스의 단점(소금,염소,열에 약함)이 없는 고가의 최신 무공해 합금 입니다. 수술시 인공뼈나 디스크 고정용볼트등의 재료로 사용되는 인체 친화적이며 완전무공해 금속입니다.

 

 

316: the first step up

If a job requires greater corrosion resistance than grade 304 can provide, grade 316 is the 'next step up'. Grade 316 has virtually the same mechanical, physical and fabrication characteristics as 304 with better corrosion resistance, particularly to pitting corrosion in chloride environments.

Grade 316 (UNS S31600) is the second most popular grade in the stainless steel family. It accounts for about 20% of all stainless steel produced.

 

Composition

Table 1 compares three related grades - 316, 316L and 316H.

Grade 316L is a low carbon 316 often used to avoid possible sensitisation corrosion in welded components.

Grade 316H has a higher carbon content than 316L, which increases the strength (particularly at temperatures above about 500oC), but should not be used for applications where sensitisation corrosion could be expected.

Table 1 - Composition on 316 and related grades

Grade   C% Mn% Si% P% S% Cr% Ni% Mo% N%
UNS 31600 316 0.08 2.0 0.75 0.045 0.03 16.0-18.0 10.0-14.0 2.0-3.0 0.10

Related Grades

UNS S31603 316L 0.03 2.0 0.75 0.045 0.03 16.0-18.0 10.0-14.0 2.0-3.0 0.10
UNS S31609 316H 0.04-0.10 2.0 0.75 0.045 0.03 16.0-18.0 10.0-14.0 2.0-3.0 -

Both 316L and 316H are available in plate and pipe, but 316H is less readily available ex-stock. 316L and 316H are sometimes stocked as standard 316 (test certificates will confirm compliance with the 'L' or 'H' specification).

Corrosion resistance

Grade 316 has excellent corrosion resistance in a wide range of media. Its main advantage over grade 304 is its increased ability to resist pitting and crevice corrosion in warm chloride environments. It resists ordinary rusting in virtually all architectural applications, and is often chosen for more aggressive environments such as sea-front buildings and fittings on wharves and piers. It is also resistant to most food processing environments, can be readily cleaned, and resists organic chemicals, dye stuffs and a wide variety of inorganic chemicals.

In hot chloride environments, grade 316 is subject to pitting and crevice corrosion and to stress corrosion cracking when subjected to tensile stresses beyond about 50oC. In these severe environments duplex grades such as 2205 (UNS S31803) or higher alloy austenitic grades including 6% molybdenum (UNS S31254) grades are more appropriate choices.

The corrosion resistances of the high and low carbon versions of 316 (316L and 316H) are the same as standard 316. They are mostly chosen to give better resistance to sensitisation in welding (316L) or for superior high temperature strength (316H).

Descriptions of these corrosion mechanisms are in ASSDA's Reference Manual.

 

Heat resistance

Like grade 304, 316 has good oxidation resistance in intermittent service to 870oC and in continuous service to 925oC. Continuous use of 316 in the 425-860oC range is not recommended if subsequent exposure to room temperature aqueous environments is anticipated, but it often performs well in temperatures fluctuating above and below this range.

Grade 316L is more resistant to carbide precipitation than standard 316 and 316H and can be used in the above temperature range. However, where high temperature strength is important, higher carbon values are required. For example, AS1210 Pressure Vessels Code limits the operating temperature of 316L to 450oC and restricts the use of 316 to carbon values of 0.04% or higher for temperatures above 550oC. 316H or the titanium-containing version 316Ti can be specified for higher temperature applications.

Like other austenitic stainless steels 316 has excellent toughness down to temperatures of liquefied gases and has application at these temperatures, although lower cost grades such as 304 are more usually selected for cryogenic vessels.

Physical and mechanical properties (see Tables 2 and 3)

Table 2: Mechanical properties of grade 316 (annealed condition) given in ASTM A240M

 

Table 3: Physical properties of grade 316 typical values in annealed condition)

Tensil strength

515MPa min

  Density

8,027kg/m3

0.2% proof stress

205MPa min

  Elastic modulus

193GPa

Elongation

40% min

 

Mean coefficient of thermal expansion

Brinell hardness

217HB max

  0 - 100oC

15.9µm/m/oC

Rockwell hardness

95HRB max

  0 - 315oC

16.2µm/m/oC

Note: Slightly different properties are given in other specifications

  0 - 538oC

17.5µm/m/ oC

      0 - 649oC

18.6µm/m/ oC

      0 - 815oC

20.0µm/m/ oC

     

Thermal conductivity

      at 100oC

16.3W/m.K

      at 500oC

21.5W/m.K

      Specific heat 0 - 100oC

500J/kg.G

      Electrical resistivity 20oC

740 nOhm.m

Like other austenitic grades, 316 in the annealed condition is virtually non magnetic (ie very low magnetic permeability). While 304 can become significantly attracted to a magnet after being cold worked, grade 316 is almost always virtually totally non-responsive. This may be a reason for selecting grade 316 in some applications.

Another characteristic that 316 has in common with other austenitic steels is that it can only be hardened by cold working. An ultimate tensile strength in excess of 1,000MPa can be achieved and, depending on quantity and product form required, it may be possible to order to a specific cold-worked strength (see ASTM A666 or EN10088-2).

Annealing (also referred to as solution treating) is the main heat treatment carried out on grade 316. This is done by heating to 1,010 1,120oC and rapidly cooling - usually by water quenching.

Fabricability

Like other austenitic stainless steels, grade 316 has excellent forming characteristics. It can be deep drawn without intermediate heat softening enabling it to be used in the manufacture of drawn stainless parts, such as sinks and saucepans. However, for normal domestic articles the extra corrosion resistance of grade 316 is not necessary. 316 is readily brake or roll formed into a variety of other parts for application in the industrial and architectural fields.

Grade 316 has outstanding weldability and all standard welding techniques can be used (although oxyacetylene is not normally used). Although post weld annealing is often not required to restore 316's corrosion resistance, making it suitable for heavy gauge fabrication, appropriate post-weld clean-up is recommended.

Machinability of 316 is lower than most carbon steels. The standard austenitic grades like 316 can be readily machined if slower speeds and heavy feeds are used, tools are rigid and sharp, and cutting fluids are used. An 'improved machinability' version of 316 also exists.

Cost comparisons

The guidelines in Table 4 are approximate 'first cost' comparisons for sheet material in a standard mill finish suitable for construction projects. The appeal of stainless over its first cost competitors dramatically increases when lifecycle costs are considered.

Table 4: First cost comparisons

Material Approximate Price ($/kg)
Glass (clear annealed) 0.2
Mild steel 1.0-1.5
Hot dip galvanised steel 1.5-2.5
304 stainless 4.0-5.0
Aluminium alloy (extruded) 4.0-5.5
316 stainless 5.0-6.0
Copper 8.0
Brass 8.5
Bronze 10.0

Source: Facet Consulting Engineers, Brisbane

Forms available

Grade 316 is available in virtually all stainless product forms including coil, sheet, plate, strip, tube, pipe, fittings, bars, angles, wire, fasteners and castings. 316L is also widely available, particularly in heavier products such as plate, pipe and bar. Most stainless steel surface finishes, from standard to special finishes, are available.

Applications

Typical applications for 316 include boat fittings and structural members; architectural components particularly in marine, polluted or industrial environments; food and beverage processing equipment; hot water systems; and plant for chemical, petrochemical, mineral processing, photographic and other industries.

Although 316 is often described as the 'marine grade', it is also seen as the first step up from the basic 304 grade.

Alternatives

Alternative grades to 316 should be considered in certain environments and applications including:

  • strong reducing acids (alternatives might be 904L, 2205 or a super duplex grade),
  • environments with temperatures above 50-60oC and with chlorides present (choose grades resistant to stress corrosion cracking and higher pitting resistance such as 2205 or a super duplex or super austenitic), and
  • applications requiring heavy section welding (316L), substantial machining (an improved machinability version of 316), high strength or hardness (perhaps a martensitic or precipitation hardening grade).

Specifications

Table 5: Some approximate equivalent designations

Wrought product

Standard UNS ASTM British German Swedish Japanese
Specification S31600 316 BS 316S16
En 58H, 58J
W. No 1,4401
DIN X5CrNiMo 18 10
SS 2347 JIS SUS 316

Cast product

Standard UNS ASTM BS3100 German AS2074  
Specification J92900 A743
CF-8M
316C16 STD 1,4408
DIN G-X6CrNiMo 18 10
H6B  

Note: For fasteners manufactured to ISO3506, 316 is included in the "A4" designation.

 

 

316: the first step up

If a job requires greater corrosion resistance than grade 304 can provide, grade 316 is the 'next step up'. Grade 316 has virtually the same mechanical, physical and fabrication characteristics as 304 with better corrosion resistance, particularly to pitting corrosion in chloride environments.

Grade 316 (UNS S31600) is the second most popular grade in the stainless steel family. It accounts for about 20% of all stainless steel produced.

Composition

Table 1 compares three related grades - 316, 316L and 316H.

Grade 316L is a low carbon 316 often used to avoid possible sensitisation corrosion in welded components.

Grade 316H has a higher carbon content than 316L, which increases the strength (particularly at temperatures above about 500oC), but should not be used for applications where sensitisation corrosion could be expected.

Table 1 - Composition on 316 and related grades

Grade   C% Mn% Si% P% S% Cr% Ni% Mo% N%
UNS 31600 316 0.08 2.0 0.75 0.045 0.03 16.0-18.0 10.0-14.0 2.0-3.0 0.10

Related Grades

UNS S31603 316L 0.03 2.0 0.75 0.045 0.03 16.0-18.0 10.0-14.0 2.0-3.0 0.10
UNS S31609 316H 0.04-0.10 2.0 0.75 0.045 0.03 16.0-18.0 10.0-14.0 2.0-3.0 -

Both 316L and 316H are available in plate and pipe, but 316H is less readily available ex-stock. 316L and 316H are sometimes stocked as standard 316 (test certificates will confirm compliance with the 'L' or 'H' specification).

Corrosion resistance

Grade 316 has excellent corrosion resistance in a wide range of media. Its main advantage over grade 304 is its increased ability to resist pitting and crevice corrosion in warm chloride environments. It resists ordinary rusting in virtually all architectural applications, and is often chosen for more aggressive environments such as sea-front buildings and fittings on wharves and piers. It is also resistant to most food processing environments, can be readily cleaned, and resists organic chemicals, dye stuffs and a wide variety of inorganic chemicals.

In hot chloride environments, grade 316 is subject to pitting and crevice corrosion and to stress corrosion cracking when subjected to tensile stresses beyond about 50oC. In these severe environments duplex grades such as 2205 (UNS S31803) or higher alloy austenitic grades including 6% molybdenum (UNS S31254) grades are more appropriate choices.

The corrosion resistances of the high and low carbon versions of 316 (316L and 316H) are the same as standard 316. They are mostly chosen to give better resistance to sensitisation in welding (316L) or for superior high temperature strength (316H).

Descriptions of these corrosion mechanisms are in ASSDA's Reference Manual.

Heat resistance

Like grade 304, 316 has good oxidation resistance in intermittent service to 870oC and in continuous service to 925oC. Continuous use of 316 in the 425-860oC range is not recommended if subsequent exposure to room temperature aqueous environments is anticipated, but it often performs well in temperatures fluctuating above and below this range.

Grade 316L is more resistant to carbide precipitation than standard 316 and 316H and can be used in the above temperature range. However, where high temperature strength is important, higher carbon values are required. For example, AS1210 Pressure Vessels Code limits the operating temperature of 316L to 450oC and restricts the use of 316 to carbon values of 0.04% or higher for temperatures above 550oC. 316H or the titanium-containing version 316Ti can be specified for higher temperature applications.

Like other austenitic stainless steels 316 has excellent toughness down to temperatures of liquefied gases and has application at these temperatures, although lower cost grades such as 304 are more usually selected for cryogenic vessels.

Physical and mechanical properties (see Tables 2 and 3)

Table 2: Mechanical properties of grade 316 (annealed condition) given in ASTM A240M

 

Table 3: Physical properties of grade 316 typical values in annealed condition)

Tensil strength

515MPa min

  Density

8,027kg/m3

0.2% proof stress

205MPa min

  Elastic modulus

193GPa

Elongation

40% min

 

Mean coefficient of thermal expansion

Brinell hardness

217HB max

  0 - 100oC

15.9µm/m/oC

Rockwell hardness

95HRB max

  0 - 315oC

16.2µm/m/oC

Note: Slightly different properties are given in other specifications

  0 - 538oC

17.5µm/m/ oC

      0 - 649oC

18.6µm/m/ oC

      0 - 815oC

20.0µm/m/ oC

     

Thermal conductivity

      at 100oC

16.3W/m.K

      at 500oC

21.5W/m.K

      Specific heat 0 - 100oC

500J/kg.G

      Electrical resistivity 20oC

740 nOhm.m

Like other austenitic grades, 316 in the annealed condition is virtually non magnetic (ie very low magnetic permeability). While 304 can become significantly attracted to a magnet after being cold worked, grade 316 is almost always virtually totally non-responsive. This may be a reason for selecting grade 316 in some applications.

Another characteristic that 316 has in common with other austenitic steels is that it can only be hardened by cold working. An ultimate tensile strength in excess of 1,000MPa can be achieved and, depending on quantity and product form required, it may be possible to order to a specific cold-worked strength (see ASTM A666 or EN10088-2).

Annealing (also referred to as solution treating) is the main heat treatment carried out on grade 316. This is done by heating to 1,010 1,120oC and rapidly cooling - usually by water quenching.

Fabricability

Like other austenitic stainless steels, grade 316 has excellent forming characteristics. It can be deep drawn without intermediate heat softening enabling it to be used in the manufacture of drawn stainless parts, such as sinks and saucepans. However, for normal domestic articles the extra corrosion resistance of grade 316 is not necessary. 316 is readily brake or roll formed into a variety of other parts for application in the industrial and architectural fields.

Grade 316 has outstanding weldability and all standard welding techniques can be used (although oxyacetylene is not normally used). Although post weld annealing is often not required to restore 316's corrosion resistance, making it suitable for heavy gauge fabrication, appropriate post-weld clean-up is recommended.

Machinability of 316 is lower than most carbon steels. The standard austenitic grades like 316 can be readily machined if slower speeds and heavy feeds are used, tools are rigid and sharp, and cutting fluids are used. An 'improved machinability' version of 316 also exists.

Cost comparisons

The guidelines in Table 4 are approximate 'first cost' comparisons for sheet material in a standard mill finish suitable for construction projects. The appeal of stainless over its first cost competitors dramatically increases when lifecycle costs are considered.

Table 4: First cost comparisons

Material Approximate Price ($/kg)
Glass (clear annealed) 0.2
Mild steel 1.0-1.5
Hot dip galvanised steel 1.5-2.5
304 stainless 4.0-5.0
Aluminium alloy (extruded) 4.0-5.5
316 stainless 5.0-6.0
Copper 8.0
Brass 8.5
Bronze 10.0

Source: Facet Consulting Engineers, Brisbane

Forms available

Grade 316 is available in virtually all stainless product forms including coil, sheet, plate, strip, tube, pipe, fittings, bars, angles, wire, fasteners and castings. 316L is also widely available, particularly in heavier products such as plate, pipe and bar. Most stainless steel surface finishes, from standard to special finishes, are available.

Applications

Typical applications for 316 include boat fittings and structural members; architectural components particularly in marine, polluted or industrial environments; food and beverage processing equipment; hot water systems; and plant for chemical, petrochemical, mineral processing, photographic and other industries.

Although 316 is often described as the 'marine grade', it is also seen as the first step up from the basic 304 grade.

Alternatives

Alternative grades to 316 should be considered in certain environments and applications including:

  • strong reducing acids (alternatives might be 904L, 2205 or a super duplex grade),
  • environments with temperatures above 50-60oC and with chlorides present (choose grades resistant to stress corrosion cracking and higher pitting resistance such as 2205 or a super duplex or super austenitic), and
  • applications requiring heavy section welding (316L), substantial machining (an improved machinability version of 316), high strength or hardness (perhaps a martensitic or precipitation hardening grade).

Specifications

Table 5: Some approximate equivalent designations

Wrought product

Standard UNS ASTM British German Swedish Japanese
Specification S31600 316 BS 316S16
En 58H, 58J
W. No 1,4401
DIN X5CrNiMo 18 10
SS 2347 JIS SUS 316

Cast product

Standard UNS ASTM BS3100 German AS2074  
Specification J92900 A743
CF-8M
316C16 STD 1,4408
DIN G-X6CrNiMo 18 10
H6B  

Note: For fasteners manufactured to ISO3506, 316 is included in the "A4" designation.

 
 
 

High Grade Stainless Steel

무공해건강냄비 2008. 6. 28. 09:06

 

304 스텐레스 스틸은 20년동안 기존 건강냄비회사에서 많이 사용하던 재질 입니다.304L(Low Carbon)은 식기,수저,냄비류에 많이 사용됩니다.

 

304: the place to start

Parliament House in CanberraUNS S30400 (grade 304) is the greatest stainless success story. It accounts for more than 50% of all stainless steel produced, represents between 50 and 60% of Australia's consumption of stainless materials and finds applications in almost every industry.

304 is not the only stainless steel and is not appropriate in every application. However, an understanding of the attributes of 304 provides an excellent base for comparing members of the austenitic family of stainless steels and a practical base for determining the appropriateness of stainless steel in a given application.

You already have substantial experience of 304 and its properties on which to draw. Chances are some of your cutlery (look for the telltale 18/8 or 18/10 designation), your saucepans, your sink or, even, the shutter on your floppy disk are 304 stainless.

Beer kegs made out of 304 Stainless

 

Composition

Grade 304L (see Table 1) is a low carbon 304 often used to avoid possible sensitisation corrosion in welded components. Grade 304H (see Table 1) has a higher carbon content than 304L, which increases the strength (particularly at temperatures above about 500oC). This grade is not designed for applications where sensitisation corrosion could be expected.

 

 

Table 1: Composition of 304 and related grades

Grade

C% Si% Mn% P% S% Cr% Ni%
UNS S30400 304 0.08 1.00 2.00 0.045 0.03 18.0-20.0 8.0-10.5

Related Grades

UNS S30403 304L 0.03 1.00 2.00 0.045 0.03 18.0-20.0 8.0-12.0
UNS S30409 304H 0.04-0.10 1.00 2.00 0.045 0.03 18.0-20.0 8.0-12.0

1. Single values are maximum specification limits.
2. These limits are specified in ASTM A240 for plate, sheet and strip. Specifications for some other products may vary slightly from these vales.

Both 304L and 304H are available in plate and pipe, but 304H is less readily available ex-stock. 304L and 304H are sometimes stocked as standard 304 (test certificates will confirm compliance with the 'L' or 'H' specification).

 

 

Corrosion resistance

cutlery.gifGrade 304 has excellent corrosion resistance in a wide range of media. It resists ordinary rusting in most architectural applications. It is also resistant to most food processing environments, can be readily cleaned, and resists organic chemicals, dye stuffs and a wide variety of inorganic chemicals.

In warm chloride environments, 304 is subject to pitting and crevice corrosion and to stress corrosion cracking when subjected to tensile stresses beyond about 50oC. However, it can be successful in warm chloride environments where exposure is intermittent and cleaning is a regular event (such as saucepans and some yacht fittings). Descriptions of these mechanisms may be found in ASSDA's Reference Manual.

 

 

 

Heat resistance

304 has good oxidation resistance in intermittent service to 870oC and in continuous service to 925oC. Continuous use of 304 in the 425-860oC range is not recommended if subsequent exposure to room temperature aqueous environments is anticipated, but it often performs well in temperatures fluctuating above and below this range. Grade 304L is more resistant to carbide precipitation and can be used in the above temperature range. Where high temperature strength is important, higher carbon values are required. For example, AS1210 Pressure Vessels Code limits the operating temperature of 304L to 425oC and restricts the use of 304 to carbon values of 0.04% or higher for temperatures above 550oC.

304 has excellent toughness down to temperatures of liquefied gases and finds application at these temperatures.

Physical and mechanical properties (see Tables 2 and 3)

 

Table 2: Mechanical properties of grade 304 (annealed condition) given in ASTM A240M

 

Table 3: Physical properties of grade 304 (typical values in annealed condition)

Tensile strength 515MPa min   Density 8,000kg/m 3
0.2% proof stress 205MPa min   Elastic modulus 193GPa
Elongation 40% min  

Mean coefficient of thermal expansion

Brinell hardness 201HB max   0-100oC 17.2?m/m/ oC
Rockwell hardness 92HRB max   0-315oC 17.8?m/m/ oC
Vickers hardness 210HV max   0-538oC 18.4?m/m/ oC

Note: Slightly different properties are given in other specifications.

 

Thermal conductivity

 

at 100oC 16.2W/m.K

 

at 500oC 21.5W/m.K

 

Specific heat 0-100oC 500J/kg.K

 

Electrical conductivity 720nOhms.m

Like other austenitic grades, 304 in the annealed condition is virtually non-magnetic (ie very low magnetic permeability). After being cold worked, however, it can become significantly attracted to a magnet (reversible by annealing).

Like other austenitic steels, 304 can only be hardened by cold working. Ultimate tensile strength in excess of 1,000MPa can be achieved and, depending on quantity and product form required, it may be possible to order to a specific cold-worked strength (see ASTM A666 or EN10088-2).

Annealing is the main heat treatment carried out on grade 304. This is accomplished by heating to 1,010-1,120oC and rapidly cooling - usually by water quenching.

 

 

Fabricability

Grade 304 has excellent forming characteristics. It can be deep drawn without intermediate heat softening - a characteristic that has made this grade dominant in the manufacture of drawn stainless parts, such as sinks and saucepans. It is readily brake or roll formed into a variety of other parts for application in the industrial, architectural and transportation fields.

Grade 304 has outstanding weldability and all standard welding techniques can be used (although oxyacetylene is not normally used). Post-weld annealing is often not required to restore 304's corrosion resistance, although appropriate post-weld clean-up is recommended. 304L does not require post-weld annealing and finds extensive use in heavy gauge fabrication.

Machinability of 304 is lower than most carbon steels. The standard austenitic grades like 304 can be readily machined, provided that slower speeds and heavy feeds are used, tools are rigid and sharp, and cutting fluids are used. An 'improved machinability' version of 304 also exists.

 

 

Cost comparisons

'First cost' cost comparisons can only be approximate, but the guidelines in Table 4 are suggested for sheet material in a standard mill finish suitable for construction projects. Lifecycle cost parameters will, in many applications, dramatically increase the appeal of stainless over its first cost competitors.

 

 

Table 4: First cost comparisons

Material Approximate
Price ($/kg)
Glass (clear ann.) 0.2
Mild steel 1.0-1.5
Hot dipped galvanised steel 1.5-2.5
304 stainless 4.0-5.0
Aluminium alloy (extruded) 4.0-5.5
316 stainless 5.0-6.0
Copper 8.0
Brass 8.5
Bronze 10.0

Source: Facet Consulting Engineers, Brisbane

 

 

Forms available

Grade 304 is available in virtually all stainless product forms, including coil, sheet, plate, strip, tube, pipe, fittings, bars, angles, wire, fasteners, castings and some others. 304 is also available with virtually all surface finishes produced on stainless steel, from standard to special finishes.

 

 

Applications

Alternative grades to 304 should be considered in certain environments and applications, including marine conditions, environments with temperatures above 50-60oC and with chlorides present, and applications requiring heavy section welding, substantial machining, high strength or hardness, or strip with very high cold-rolled strength.

However, typical applications for 304 include holloware, architecture, food and beverage processing, equipment and utensils, commercial and domestic kitchen construction, sinks, and plant for chemical, petrochemical, mineral processing and other industries.

With this breadth of application, grade 304 has become a fundamental alloy in modern industry and is certainly worth committing to your materials knowledge base.

Table 5: Some approximate equivalent designations

 

Wrought product

Standard UNS ASTM British German Swedish Japanese
Specification S30400 304 BS 304S15
En 58E
W. No 1.4301
DIN X5CrNi 18 9
SS 2332 JIS SUS 304

Cast product

Standard UNS ASTM BS3100 German AS2074  
Specification J92600 A743 CF-8 304C15 STD No. 4308
DIN G-X6CrNi 18 9
H5A  
Note: For fasteners manufactured to ISO3506, 304 is included in the 'A2' designation.