中文版Now the commonly used material standard letter includes:
ISO (international)
GB (China
DIN (Germany)
AISI/SAE (US)
JIS (Japan)
The bolt substandard thread uses the material
Some do not have the mechanical property request perhaps ISO Class 4.8 SAE the Grade 1-2 low carbon steel fasteners, with Q235A SAE 1015 DIN C15 sufficiently, simply does not want any heat treatment, the direct cold finishing makes, but the rank is slightly high a spot the fastener for example: ISO Class 6.8 SAE the Grade 3-4 pieces must use the carbon amount in 0.2% above steel, like C1020 C1022 Ml20 ML35 and so on, this kind of screw does not need any heat treatment, the cold finishing intensity definitely may satisfy the request. In fact the carbon amount is higher, the cold formation is more difficult, is also not unnecessary is 6.8 levels of screws uses a talented person in an insignificant position, the peculiar circumstance regarded as another matter.
We most commonly used are ISO Class 8.8 SAE the Grade 5 screws, generally uses the medium carbon steel, ML35 SAE 1035 DIN 35 JIS SWRCH35K after the heat treatment (quenching + tempering), may also use SAE5140 40Cr and so on, alloying element increase has the very big help to the heat treatment hardenability, therefore the specification big screw may choose uses the alloy steel, does not send in uses the central spot which the medium carbon steel caused us often to say “to quench the phenomenon existence airtight”.
ISO Class 9.8 10.9 SAE the Grade 8 pieces must use to lower to the medium alloy steel material, passes through the heat treatment (quenching + tempering), has a very good union with the alloy material in the material mechanical property aspect, the commonly used material is 40Cr 35CrMo SAE5140 SCM435 SAE4135 SAE4137 JIS SCr440(H) DIN 41Cr4 and so on, in fact 45# may also meet the requirements the mechanical property, but must have inferior slightly in the synthesis mechanical property aspect compared to the alloy steel.
ISO Class12.9 SATM A574 is one to the mechanical property request very high high strength bolt, then must with the carbon alloy steel after the heat treatment (quenching + tempering), if SCM435 35CrMo SAE 4137 SAE4135 DIN 34CrMo4, this kind of high strength bolt if the surface treatment must pass through time acid pickling this working procedure, will have the hydrogen embrittlement phenomenon, must therefore certainly have dehydrogenation this working procedure (is specially has acute angle's fastener), will otherwise die is very miserable.
Box threads and so on nut use the material
Does not have the mechanical property request perhaps ISO Class 5-6 SAE Grade 3-4 generally with C1010 Q235A or C15, does not need the heat treatment, the cold finishing then. ISO Class 8, SAE Grade 5, must use Ml35 SAE1035 DIN C35 generally, the small specification's nut does not need the heat place then to reach the request the mechanical property, the specification big must pass through the heat treatment (quenching + tempering), this GB3098.2 said is very clear.
ISO Class 10, SAE the Grade 8 general use medium carbon steels then meets its intensity requirements after the heat treatment. If medium carbon steels and so on SAE1035. Some point is everybody must pay attention, the nut and the bolt are different, its stress mainly compresses but must promotes primarily, not only therefore nut's intensity with material related, but also and many factors related, including in precision, pitch, nut bevel edge, nut thickness ......
Plain washer needed materials
Not mechanical property request plain washer generally with angle material manufacture, as soon as when Q235A, has degree of hardness requests not to be but high may use the thick sheet rolling to issue the request degree of hardness. Shoots gasket which the pad and so on against pine uses generally with 65Mn 70# or S 50CM-S 70CM manufacture, must pass through the heat treatment (quenching + tempering)
The rivet, sells the axis class
The rivet, sells the axis class common needed materials and the bolt is the same, but some rivet degree of hardness cannot be too high, even somewhat requests below HRB60, generally normalized material degree of hardness in HRB70-80, therefore some must be able to achieve the performance requirement after the annealing.
From attacks the nail generally with materials and so on C1018 C1020 C1022, but domestic some factories to save the cost, cheats on labor and materials, uses 18# 15# 20# to use a factory to use Q235A, then case hardening processing finished up, like this made from attacks nail its core toughness not to be able to meet the requirements, easy to break.
The stainless steel fastener myself understand not many, probably SUS304 is very commonly used.
Material other special requests
If the company must make the fastener which uses in welding uses, the arc welding and the gas welding do not have what request generally to the material. What if customer with is a spot welding, that wants the little darling to do with the low-carbon steel, if must certainly gain in strength, may use some low-carbon to contain the Mn element high material. Here is only a very simple example, many are can note in the actual production.
When the customer assigns must use some kind of trademark the material, but the company for a while does not have this material, or this material is not easy in the market to purchase, may understand that the customer this fastener's use, in meets under the mechanical property requirement to be possible to propose the written application request substitution material. Some purchase customer to the fastener is not very specialized, to material choice not necessarily for best, does for our specialized production fastener's factory, may give a customer better suggestion, achieves the benefit double to receive.
Certainly the fastener must pay attention with the material continues these, before for example the material use, wanted certainly the obsolete effective date (before I wrote one specially about this aspect article), the superficial rusted and rotten material used in making some perfect thread fastener or using in the fastener which the surface must grind, the material Central tissue also has the shrink hole not to use in making throws the bald screw ......
The material applies ever changing, the use is appropriate, turns the clear water into the chicken soup, uses improper, the small piece creates the waste, increases the cost, then the company possibly must lose many one batch of money greatly!
