CARBON STEEL
According to the requirements of DSTU ISO 898-1:2003, the following steel grades are used to manufacture bolts, screws and studs:
Carbon steel is an alloy of iron (Fe) and carbon (C). Low-carbon steel (C≤0.25%), medium-carbon steel (0.25%<C≤0.55%) and high-carbon steel (C>0.55%) are distinguished.
For abbreviated designations, use the following markings in the documentation:
St – steel;
St3 – steel with a carbon content of 0.3%;
St2 – steel with a carbon content of 0.2%.
Carbon steels are categorized into groups:
A – products are controlled by chemical composition (carbon);
B – controlled only by mechanical properties;
C – controlled by mechanical and chemical composition.
At the same time, group A hardware is not indicated in the product designation. Examples of designations of groups B and C: BSt3 and BSt2.
Carbon steels for metalware production have deoxidation levels:
Kp – boiling steel (BSS3Kp) has a porous structure;
Ps is a semi-quiescent (Wt2Ps) structure that is less porous than Kp;
Sp – calm steel (not indicated).
Enrichment (deoxidation) is performed with ferromanganese.
Only boiling steels are used for high-strength drawing of products for subsequent stamping (bolts, screws). However, these products must not be welded.
Structural carbon steel of quality GOST 1050-80
Examples of designations: Steel 20 (0.20% carbon), Steel 35 Kp GOST 1050-88.
This group of steels is not divided into groups A, B, and C, but is divided by the degree of deoxidation.
“Harmful” additives for this group of steels (the percentage of which must be controlled) are:
S (sulfur) – the maximum content should not exceed 0.035%. Excessive amounts cause brittleness and brittleness when heated;
P (phosphorus) – the maximum content should not exceed 0.035%. If exceeded, it causes cold brittleness (steel loses its load-bearing capacity at temperatures below -30 C).
Alloy steel is a carbon steel with additional elements (alloying additives) added to its chemical composition. We distinguish between low-alloy steels (alloying element content up to 2÷4%), medium-alloy steels (4÷11%) and high-alloy steels (over 11%). Alloying elements do not include carbon and unavoidable impurities.
List of impurities in alloy steels:
Cr – chromium; Si – silicon; Mn – manganese; Ni – nickel; B – boron; Al – aluminum; Ti – titanium; W – tungsten; V – vanadium.
Everything except boron is labeled with a letter and percentage in the name. For example, 40X13.
40X steel – carbon content from 0.36 to 0.44%
Brinell hardness for hardware according to GOST 22353 280 -363 NV.
40X select steel – carbon content from 0.37 to 0.42%
Alloy steels are definitely only calm in terms of deoxidation.
A couple of examples of decoding alloy steel markings:
Steel 12KhN3A GOST 4543-88, where A is the designation of high-quality steel;
Steel 20KhGR – bolt strength class 8.8;
Steel 40X – bolt strength class 8.8 and 10.9;
Steel 40KhM (40NM – European production of products) – bolt strength class 10.9 and 12.9.
According to the requirements of DSTU ISO 898-2:2004, the following steel grades are used to manufacture nuts:
| Strength class | Limitations on chemical composition (control analysis), %. | ||||
| carbon | manganese | phosphorus | sulfur | ||
| max | min | max | max | ||
| 4; 5; 6 | – | 0,50 | – | 0,060 | 0,150 |
| 8; 9 | 04 | 0,58 | 0,25 | 0,060 | 0,150 |
| 10 | 05 | 0,58 | 0,30 | 0,048 | 0,058 |
| 12 | – | 0,58 | 0,45 | 0,048 | 0,058 |
In accordance with GOST 18123-82, the following steel grades are used to manufacture washers:
| View | Mark | Standard designation | Brand (group) designation |
| Carbon steels | 08, 08kp
10, 10kp |
GOST 1050-88 | 01 |
| St3
St3 kp |
GOST 380-94 | 02 | |
| 15 | GOST 1050-88 | 03 | |
| 20 | 04 | ||
| 35 | 05 | ||
| 45 | 06 | ||
| Alloy steels | 40Х | GOST 4543-71 |
11 |
CORROSION-RESISTANT STEEL
In accordance with the requirements of DSTU ISO 3506-1:2006, bolts, screws, studs and nuts are made of the following stainless steel grades:
| Class | Mark | Restrictions on chemical composition, %. | ||||||||
| C | Si | Mn | P | S | Cr | Mo | Ni | Cu | ||
| Austenitic | А1 | 0,12 | 1,00 | 6,50 | 0,20 | 0,15÷0,35 | 16,00÷19,00 | 0,70 | 5,00÷10,00 | 1,75÷2,25 |
| А2 | 0,10 | 1,00 | 2,00 | 0,05 | 0,03 | 15,00÷20,00 | – | 8,00÷19,00 | 4,00 | |
| А3 | 0,08 | 1,00 | 2,00 | 0,045 | 0,03 | 17,00÷19,00 | – | 9,00÷12,00 | 1,00 | |
| А4 | 0,08 | 1,00 | 2,00 | 0,045 | 0,03 | 16,00÷18,50 | 2,00÷3,00 | 10,00÷15,00 | 1,00 | |
| А5 | 0,08 | 1,00 | 2,00 | 0,045 | 0,03 | 16,00÷18,50 | 2,00÷3,00 | 10,50÷14,00 | 1,00 | |
| Martensitic | С1 | 0,09÷0,15 | 1,00 | 1,00 | 0,05 | 0,03 | 11,50÷14,00 | – | 1,00 | – |
| С3 | 0,17÷0,25 | 1,00 | 1,00 | 0,04 | 0,03 | 16,00÷18,00 | – | 1,50÷2,50 | – | |
| С4 | 0,08÷0,15 | 1,00 | 1,50 | 0,06 | 0,15÷0,35 | 12,00÷14,00 | 0,60 | 1,00 | – | |
| Ferritic | F1 | 0,12 | 1,00 | 1,00 | 0,04 | 0,03 | 15,00÷18,00 | – | 1,00 |
– |
Corrosion-resistant steel is a high-alloy steel. The main alloying elements are chromium (Cr) and nickel (Ni). For steel to be considered “stainless,” the chromium content must be more than 13%.
Austenitic steel is a steel with the main components of 15-20% chromium and 5-19% nickel, which increases corrosion resistance. It cannot be hardened and is usually not magnetic. It is well suited for heat treatment and welding. It is the austenitic group of steels that is most widely used in industry and in the manufacture of fasteners.
A1 – has low corrosion-resistant properties due to its high sulfur content.
A2 is a non-toxic, non-hardening, corrosion-resistant steel. It is easy to weld and does not become brittle. Fasteners and products made of A2 steel are not suitable for use in oxygen-free acids and chloride-containing environments, such as swimming pools and seawater. Suitable for temperatures down to -200 0C.
A4 – similar to A2 steel, but with the addition of 2-3% molybdenum, which significantly increases its anti-corrosion properties. This steel grade is designed for use in boiling sulfuric acid and is also suitable for use in chloride-containing environments to a certain extent. Fasteners and rigging products made of A4 are recommended for use in shipbuilding. Suitable for temperatures down to -60 0C.
In accordance with GOST 18123-82, the following steel grades are used to manufacture washers:
| View | Mark | Standard designation | Brand (group) designation |
| Corrosion-resistant steels | 12X18H10T | GOST 5632-72 | 21 |
| 20Х13 | 22 |
NON-FERROUS METAL ALLOYS
Non-ferrous metal alloys are used to manufacture parts that operate in aggressive environments, are subject to friction, and require high thermal conductivity, electrical conductivity, and reduced weight. They are used in shipbuilding and aircraft construction.
In accordance with GOST 1759.0-87, bolts, screws, studs and nuts are made from the following non-ferrous metal alloy grades:
| Symbolic designation | Material or alloy grade | Standard designation |
| 31 | AMg5P
AMg5 |
GOST 4784-74 |
| 32 | Brass L63
Brass LS59-1 |
GOST 15527-70
GOST 12920-67 |
| 33 | Brass L63 antimagnetic
Brass LS59-1 antimagnetic |
|
| 34 | Bronze Br. AMC 9-2 | GOST 18175-78 |
| 35 | Д1,
D1P, D16, D16P |
GOST 4784-74 |
Brass is an alloy of copper (Cu) and zinc (Zn).
Bronze is an alloy of copper (Cu) with tin (Sn) or other alloying elements except zinc (Zn) and nickel (Ni), in which case brass and nickel are produced, respectively.
In accordance with GOST 18123-82, the following non-ferrous metals and alloys are used for the manufacture of washers:
| View | Mark | Standard designation | Brand (group) designation |
| Brasses | Л63 | GOST 15527-70 | 32 |
| LS59-1 | |||
| L63 antimagnetic | 33 | ||
| Bronze | Br. AMC 9-2 | GOST 18175-78 | 34 |
| Copper | М3 | GOST 859-78 | 38 |
| Aluminum alloys | Amg5 | GOST 4784-97 | 31 |
| Д1 | 35 | ||
| AD1 | 37 |