Stainless steel bolt material
Introduction to characteristics of stainless steel (304, 316)
(a) the three materials are all 300 series austenitic stainless steel, the chemical composition is as follows:
Name C Si Mn P S Ni Cr Mo Cu
304M ≤0.06 ≤1.0 ≤2.0 ≤0.045 ≤0.03 8.91-10.0 18.0-20.0 00
316 ≤0.03-0.06 ≤1.0 ≤2.0 ≤0.045 ≤0.03 0.0-14.0 16.0-18.0 2.0-3.0 0
304HC ≤0.08 ≤1.0 ≤2.0 ≤0.045 ≤0.03 8.0-10.5 17.0-19.0 0 1.0-3.0
The relationship between the main chemical composition and the properties of stainless steel.
1. Carbon C can increase hardness and strength, and high content will reduce its ductility and corrosion resistance
2, chromium Cr can increase the corrosion resistance, oxidation resistance, fine grain, increase the strength, hardness and wear resistance
3, nickel Ni can increase high temperature strength, corrosion resistance, reduce the rate of cold work hardening
4. Molybdenum Mo increases strength and has excellent corrosion resistance to oxides and seawater
5. Copper Cu is conducive to cold processing and forming, reducing magnetism
At present, common stainless steel bolt materials on the market mainly include:
302HQ (0Cr18Ni9Cu3) - mainly used for self attack nails;
SUS304 (0Cr18Ni9) - also known as A2, is mainly used for the manufacture of ordinary stainless steel bolts, screws, washers and nuts, the strength class of bolts is generally 70; SUS 316 (0Cr18Ni12Mo2) SUS 316L (00Cr17Ni14Mo2) - commonly known as A4 is used for the manufacture of stainless steel bolts, screws, washers and nuts with high corrosion resistance.
Stainless steel flange bolt material introduce material has nothing to do with the material of flange bolts, according to the European system HG20613-97 "steel pipe flange with fasteners (the European system) HG20614-97" steel pipe flange gasket fasteners to choose (the European system) ", according to the American system HG20634-97 "steel pipe flange with fasteners (system) of America HG20635-97" steel pipe flange gasket fasteners selection system (America), Carbon steel, stainless steel flange is usually used to meet the requirements of the special class 35CrMoA.
Stainless steel flange does not have to use stainless steel bolt, the choice of stainless steel bolt is to facilitate disassembly (carbon steel is easy to rust), in some can not fire or other special occasions can be chosen;
The use of carbon steel bolts also do not necessarily need to add insulation gaskets and casings, plus insulation gaskets and casings are only used for the possibility of electrification or fluid in the pipeline is flammable and explosive occasions, the use of stainless steel bolts also need to add insulation gaskets and casings.
Flange material is not the basis of bolt material selection, as long as the pre - tightening force is enough. Stainless steel flange connection bolt material introduction stainless steel flange 430 type ordinary chromium steel, its corrosion resistance and heat resistance performance is better than 410 type, magnetic, but it can not heat treatment strengthening, and it is suitable for corrosion resistance and heat resistance performance slightly higher, general strength requirements of stainless steel stainless steel bolts.
Martensitic stainless steel
Models 410 and 416 can be heat treated to strengthen, hardness in 35 ~ 45HRC, good machining performance, for general use
Stainless steel bolts for heat and corrosion resistance. Type 416 has a slightly higher sulfur content and is free-cutting stainless steel.
Type 420, sulfur content? R0.15%, mechanical properties improved, heat treatment can be strengthened, the maximum hardness value of 53 ~ 58HRC,
For stainless steel bolts requiring high strength.
Precipitated hardened stainless steel
17-4ph, ph15-7mo, they can achieve higher strength than the usual type 18-8 stainless steel, and are therefore used for high strength, corrosion resistant stainless steel stainless steel bolts. A-286, A non-standard stainless steel, has higher corrosion resistance than the commonly used type 18-8 stainless steel, as well as excellent mechanical properties at higher temperatures. Used for high strength, heat resistant, corrosion resistant stainless steel bolts, can be used up to 650 ~ 700℃.
8.8-grade bolt strength refers to the shear stress resistance of the bolt with grades of 8.8GPa and 10.9 GPa 8.8 nominal tensile strength 800N/MM2 nominal yield strength 640N/MM2
The material selected for the 8.8 hexagon bolts is 1035ACR(below M10)1040ACR (above M12) CH38F 1045ACR 1039 10B21 10B33 10B38
The material selected for 8.8 grade inner hexagon bolts is CH38F 1039 10B21 (m10-m12) 10B33 (M14) 10B38 (m12-m24) The strength rating of 8.8 and 10.9 refers to the shear stress rating of the bolt of 8.8GPa and 10.9 GPa
Nominal tensile strength 800N/MM2 nominal yield strength 640N/MM2 general bolts are represented by "X.Y", X*100= the tensile strength of the bolt, X*100* (Y/10) = the yield strength of the bolt
(because according to the mark: yield strength/tensile strength =Y/10)
