Common Stainless Steel Material For Fasteners And Principle Of Material Selection

Fasteners are commonly used parts in mechanical equipment, and their usage rate is very high. There are also many types of fasteners, usually screws, nuts, bolts, rivets, and so on. In order to ensure the safety of fastener use, we will have certain principles in the selection of materials. Based on the knowledge of fasteners, today Xinchi Fastener Company is glad to share the commonly used stainless steel materials of fasteners and stainless steel material selection principles for fasteners.

The principle of choosing stainless steel materials for fasteners

Under normal circumstances, we need to consider the following aspects of the selection of stainless steel material for fasteners.

• Requirements for fastener materials in terms of mechanical properties, especially strength.
• Requirements for corrosion resistance of materials under working conditions.
• Operating temperature requirements for heat resistance (high temperature, strength, oxidation resistance) of materials.
• Production technology to material processing performance requirements.
• Other factors, such as weight, price, and purchase, should be considered.

After comprehensive consideration of these five aspects, the brand, variety, specifications, and material standards of selected fasteners are finally determined.

What stainless steel materials are commonly used for fasteners?

Austenitic grade stainless steel

The four commonly used grades are 302, 303, 304, and 305, that is, the so-called “18-8” type austenitic stainless steel these four grades. Both corrosion resistance and mechanical properties are similar. The starting point of material selection is fastener production technology. The method, in turn, depends on the size and shape of the fasteners, as well as on the number produced.

Type 302 Austenitic stainless steel is used for machined screws and tapping bolts.

Type 303 is designed to improve machining performance. A small amount of sulfur is added to type 303 stainless steel for machining nuts with bar material.

Type 304 is suitable for fasteners processed by the hot heading process, such as bolts of longer specification and bolts of large diameter, which may be beyond the scope of the cold heading process.

Type 305 is suitable for cold heading processing of fasteners, such as cold-forming nuts, hex bolts, etc.

Models 309 and 310, which have higher Cr and Ni content than type 18-8 stainless steel, are suitable for fasteners working at high temperatures.

Both types 316 and 317 contain the alloying element Mo, so their high-temperature strength and corrosion resistance are higher than type 18-8 stainless steel.

Type 321 contains the relatively stable alloy element Ti and Type 347 contains Nb, which improves the resistance to intergranular corrosion. They are suitable for fasteners that are not annealed after welding or are in service from 420 to 1013C.

Ferritic stainless steel

Type 430 ordinary chromium steel is magnetic, and its corrosion resistance and heat resistance is better than 410, but it can not be heat treatment strengthening. Therefore, it is suitable for stainless steel fasteners with high corrosion and heat resistance and low strength requirements.

Martensitic stainless steel

Type 410 and type 416 martensitic stainless sheets of steel can be strengthened by heat treatment. Their hardness ranges from 35 HRC to 45HRC, and their machinability is good, so they can be used for general-purpose heat and corrosion-resistant fasteners. Type 416 has a slightly higher sulfur content and is free-cutting stainless steel.

Precipitation-hardening stainless steel

17-4PH and PH15-7Mo are used for high-strength, corrosion-resistant stainless steel fasteners because they are stronger than the usual type 18-8 stainless steel.

A-286 is A non-standard stainless steel that has higher corrosion resistance than the commonly used 18-8 stainless steel, as well as excellent mechanical properties at higher temperatures. Therefore, it can be used as a high-strength, heat-resistant, corrosion-resistant fastener, and the use temperature can reach 650~700 degrees Celsius.

Anji Xinchi Fastening Piece Co., Ltd is a trustworthy fastener company, especially in furniture nuts. And we are the designated fastener supplier to“STAPLE”. As a trusted fastener supplier,  Xinchi Fastener Company can offer a wide range of high-quality fasteners, including tee nuts, screws, bolts, rivets, washers, etc. If you want to know more about fasteners or want to wholesale fasteners, please feel free to contact us. And then our experienced and expert service team will reply to you as soon as possible.