Stainless steel bolts are one of the professional stainless steel fasteners produced by Jinming Hardware. When purchasing stainless steel bolts, some customers do not understand the standard specifications of stainless steel bolts. The following is a brief introduction of Jinyu screws.
Stainless steel bolt standards can refer to carbon steel bolt standards. Specifically according to international standards such as GB / T6170-2000 and GB / T5782-2000. The mechanical performance grade codes of stainless steel bolts and nuts are: A2-70 (0r18Ni9); A4-70 (0Cr17Ni12Mo2).
High-strength steel bolts and grades for steel joints of standard specifications. This specification covers two types of hardened and quenched and tempered alloy steel, large hexagon bolts for structural use, and tensile strength of 1040-1210 MPa. The American Institute of Building and Industrial Fasteners Association has approved the use of steel structural bolts ASTM A325 and A 490 bolts by the research committee. These bolts can be used in structures. Bolt specifications include bolt diameters M12-M36. They specify the type to indicate the chemical composition as follows: Type Description Description Type 1 Medium carbon alloy steel. This specification applies to research committees using ASTM A 325 and A 490 large hex structural bolts in their published steel structure codes. This standard states that imperial / pound is considered the only unit of measurement. No other unit of measure is included in the standard. This standard is not intended to deal with all potential safety hazards, if any, it has nothing to do with this standard. It is the responsibility of the user to determine the applicability and limitations of this standard before establishing appropriate safety and health practices. American Society for Testing Materials Standard A325. Specifications are A325 heat treated, high strength steel bolts with a minimum tensile strength of 120/105 kB / A 490. Grade A490 high strength bolts 10.9 and 10.9.3 are used for steel structural joints. A 563M Specification for Carbon and Alloy Steel Nuts (Metric) Specifications are A563M carbon steel and alloy steel nuts (metrics). The nut complies with the requirements of the A563M specification and is used in conjunction with the large hexagon bolt specification A 490M. Various grades of nut surface finish requirements are as follows: Bolt Type and Finish Nut Class and Finish Nut final selection. The alloys identified by the American Iron and Steel Institute are, within the maximum range of alloys. Elements exceed one or more of the following ranges: manganese, 1.65%. 0.60%; copper, silicon, 0.60%; or any specified element within a certain range or a clear, MOQ limit, requires the construction of approved alloy steel, aluminum, chromium to: 3.99%, Cobalt, columnum, molybdenum, nickel-titanium, tungsten, vanadium, zirconium, or any other, alloying elements are added to obtain the required alloying effect. Bolts with smaller diameter M24 have lengths ranging from 21.4 D to 2D, but cannot do so. The tensile test shall be the axial tension of the wedge, and shall comply with the minimum tensile load and proof load, or the agency proof load table 4. The bolt has a small diameter and a length M24 shorter than the hardness required for the 2D axial tensile test. After the hardness and tension tests of these two pairs of bolts are completed as required, the first reading with a low hardness is recorded. The purpose of this test is to evaluate the complete and incomplete decarburization and core hardness determined by the presence near different surfaces.
After comprehensive and comprehensive consideration of these five aspects, the grade, variety, specification and material standard of stainless steel bolts were finally determined.
Ferritic stainless steel
Type 430 ordinary chrome steel, which has better corrosion resistance and heat resistance than type 410 and has magnetic properties, but it cannot be strengthened by heat treatment. It is suitable for stainless steel with general requirements for strength and corrosion resistance and heat resistance. bolt.
Martensitic stainless steel
Types 410 and 416 can be strengthened by heat treatment, hardness is 35 ～ 45HRC, good machining performance, heat-resistant and corrosion-resistant stainless steel bolts for general use. Type 416 has a slightly higher sulfur content and is a free-cutting stainless steel.
Type 420, sulfur content? R0.15%, improved mechanical properties, heat treatment and strengthening, maximum hardness value 53 ~ 58HRC, used for stainless steel bolts requiring higher strength.
Precipitation hardened stainless steel
17-4PH, PH15-7Mo, they can get higher strength than ordinary 18-8 stainless steel, so they are 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 18-8 stainless steel, and still has good mechanical properties at elevated temperatures. Used as high-strength, heat-resistant and corrosion-resistant stainless steel bolts, can be used to 650 ~ 700 ℃.
Austenitic stainless steel
The commonly used grades are four grades 302, 303, 304, and 305, the so-called "18-8" austenitic stainless steel. Both the corrosion resistance and the mechanical properties are similar. The starting point chosen is the production process method of stainless steel bolts, which depends on the size and shape of the stainless steel bolts, and also depends on the quantity produced.
Type 302 is used for machined screws and self-tapping bolts.
Type 303 In order to improve cutting performance, a small amount of sulfur is added to type 303 stainless steel, which is used to process nuts using bar stock.
Type 304 is suitable for processing stainless steel bolts by hot heading, such as longer specifications, large diameter bolts, which may exceed the scope of cold heading.
Type 305 is suitable for processing stainless steel bolts by cold heading, such as cold-formed nuts, hexagon bolts.
Types 309 and 310 have higher Cr and Ni contents than 18-8 stainless steel, and are suitable for stainless steel bolts working at high temperatures.
Types 316 and 317 both contain the alloying element Mo, so their high temperature strength and corrosion resistance are higher than those of 18-8 stainless steel.
Types 321 and 347, type 321 contains the more stable alloying element Ti, and type 347 contains Nb, thereby improving the intergranular corrosion resistance of the material. It is suitable for stainless steel standard parts that are not annealed or serviced at 420 ～ 1013 ℃.