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Fasteners on the knowledge

Fasteners is the basis of pieces of machinery, great demand, usually bolts, screws, rivets, etc. In order to ensure safety in general do not have to consider the temperature or the impact of adverse environmental or other dangerous conditions. The materials are commonly used carbon steel, low-alloy steel and nonferrous metals. However, in certain situations, fasteners meet the material needs of serious corrosion or high-intensity conditions, there are many super-strength stainless steel and stainless steel came into being.
In this paper, a brief introduction to the fine production of stainless steel fasteners. Most are made of stainless steel or steel wire rod production for fasteners, austenitic stainless steel, ferrite stainless steel, martensitic stainless steel, precipitation hardening stainless steel.
First, the principle of selection
Stainless steel materials, mainly from the choice of the following five aspects to consider.
1, the fasteners in the mechanical properties of materials, in particular the requirements in terms of strength;
2, the working conditions of the anti-corrosive materials to the requirements;
3, the working temperature of the heat resistance of materials (high temperature strength, anti-oxidation performance) requirements;
4, the production process in the material processing performance requirements;
5, other aspects, such as weight, price, procurement factors to consider.
Through these five areas to conduct a comprehensive and integrated consideration, the final determination of the choice of fasteners grades, varieties, specifications, material standards.
Second, austenitic stainless steel
302,303,304,305 common grades for four grades, namely, the so-called "18-8" type austenitic stainless steel four grades. Whether anti-corrosive, or its mechanical properties are similar. Selection is the starting point approach Fastener of the production process, and the method depends on the size and shape of fasteners, also depends on the number of production.
302-processing machinery used for the self-tapping screws and bolts.
303-cutting in order to improve the performance, type 303 stainless steel add a small amount of sulfur, for the use of bar nut processing.
304-applicable to the use of upsetting the processing of fasteners, bolts specifications such as a longer, large-diameter bolts, which may be beyond the scope of cold upsetting.
305 apply to the type of processing with cold upsetting fasteners, such as cold forming nuts, bolts 2.60.
309-and 310-type, with their capacity and Cr-Ni volume than 18-8 stainless steel, high temperature apply to the work of the fasteners.
316 and 317 type, they all contain alloying elements Mo, a result of their high temperature strength and corrosion resistance of stainless steel higher than 18-8.
321-and 347-, 321-alloy containing more stable elements Ti, 347-containing Nb, thereby enhancing the material between the anti-corrosion crystal. Does not apply to welding after annealing, or 420 ~ 1013 ℃ in the service of fasteners.
Third, iron-size stainless steel
430-ordinary chrome steel, corrosion resistance and heat resistance than 410, and a magnetic, but it can not strengthen the heat treatment, apply to and corrosion-resistant and heat resistance slightly higher, the general strength of the stainless steel retention requirements Pieces.
4. Martensitic stainless steel
410-and 416-heat treatment can be enhanced, hardness in the 35 ~ 45 HRC, machining good performance for the general purpose of heat-resistant corrosion-resistant fasteners. 416-slightly higher sulphur content, is easy to cut stainless steel.
420 type, sulphur ≧ 0.15%, improving the mechanical properties, heat treatment can be enhanced, the biggest hardness of 53 ~ 58 HRC, to require a higher strength of fasteners.
5, precipitation hardening stainless steel
17-4PH, PH15-7Mo, they can often than the 18-8 stainless steel a higher intensity, they have been used for high-strength, corrosion-resistant stainless steel fasteners.
A-286, a non-standard stainless steel, than the commonly used 18-8 stainless steel with a higher corrosion resistance and higher temperature still has good mechanical properties. Used as high-strength, heat and corrosion-resistant fasteners, can be used to 650 ~ 700 ℃. With stainless steel fasteners components

Grades
C
Ni
Cr
Mn
Si
S
P
Other
Chinese brands (similar)
302
0.15
7.0 ~ 10.0
17.0 ~ 19.0
2.0
1.0
0.03
0.045
 
1Cr18N9
303
0.15
8.0 ~ 10.0
17.0 ~ 19.0
2.0
1.0
0.15
0.20
Mo0.06
1Cr18Ni9
304
0.08
8.0 ~ 10.5
18.0 ~ 20.0
2.0
1.0
0.03
0.045
 
0Cr19Ni9
305
0.12
10.0 ~ 13.0
17.0 ~ 19.0
2.0
1.0
0.03
0.045
 
1Cr18Ni12
309
0.08
12.0 ~ 15.0
22.0 ~ 24.0
2.0
1.0
0.03
0.045
 
 
310
0.25
19.0 ~ 20.0
24.0 ~ 26.0
2.0
1.5
0.03
0.045
 
 
316
0.08
10.0 ~ 14.0
16.0 ~ 18.0
2.0
1.0
0.03
0.045
Mo2.0 ~ 3.0
0Cr17Ni12Mo2
317
0.03
11.0 ~ 15.0
18.0 ~ 20.0
2.0
1.0
0.03
0.045
Mo3.0 ~ 4.0
0Cr18Ni12Mo3Ti
321
0.08
9.0 ~ 12.0
17.0 ~ 19.0
2.0
1.0
0.03
0.045
Ti
0Cr18Ni9Ti
347
0.08
9.0 ~ 13.0
17.0 ~ 19.0
2.0
1.0
0.03
0.045
Nb
1Cr18Ni11Nb
430
0.12
 
16.0 ~ 18.0
1.0
1.0
0.03
0.04
 
1Cr17
410
0.15
 
11.5 ~ 13.5
1.0
1.0
0.03
0.04
 
1Cr13
416
0.15
 
12.0 ~ 14.0
1.25
1.25
0.15
0.04
 
2Cr13Ni2
420
≧ 0.15
 
12.0 ~ 14.0
1.0
1.0
0.03
0.04
 
2Cr13
17-4PH
0.07
3.0 ~ 5.0
15.0 ~ 17.5
1.0
1.0
0.03
0.04
Cu3.0 ~ 5.0
0Cr17Ni4Cu4Nb
PH15-7Mo
0.09
6.5 ~ 7.75
16.0 ~ 18.0
1.0
1.0
0.03
0.04
Al0.75 ~ 1.5
0Cr17Ni7Al
A-286
0.08
24.0 ~ 27.0
13.5 ~ 16.0
2.0
2.0
0.03
0.04
Mo1.0 ~ 1.5 Ti1.9 ~ 2.35 V0.10 ~ 0.50