In the structure of plastic products, the material of the screws is related to the factors required by the product, such as the size of the force, and stainless steel is used on the outside of the plastic, and carbon steel screws are used on the inside. How to choose stainless steel?
1: In layman’s terms, carbon steel screws do not have steel with alloy elements added deliberately, and stainless steel screws are steel with high alloy content added for rust prevention.
2: Stainless steel screws are far more expensive than carbon steel screws.
3: These two kinds of screws are different, so they cannot be compared. Carbon steel screws are usually stronger than stainless steel screws, but they are easy to rust.
The materials of stainless steel screws and carbon steel screws are different, and the environment of use is also different. Carbon steel has poor corrosion resistance, and the bolts will rust to death after a long time. Stainless steel screws are relatively better.
Stainless steel screw
The materials of stainless steel screws and carbon steel screws are different, and the environments in which they are used are also different.
The corrosion resistance of carbon steel is relatively poor, and the bolts will rust to death after a long time. Stainless steel bolts are relatively better. Here are some materials for stainless steel bolts:
Material classification of stainless steel screws
It is used for the production of stainless steel screws. The materials of stainless steel screws are classified into austenitic stainless steel, ferritic stainless steel, martensitic stainless steel and precipitation hardening stainless steel. The selection of stainless steel screws is also in principle. From what aspect, let you choose the stainless steel screws you need.
After comprehensive and comprehensive consideration of these five aspects, the grade, variety, specification and material standard of stainless steel screws are finally determined.
Ferritic stainless steel
Type 430 ordinary chromium steel has better corrosion resistance and heat resistance than Type 410, and is magnetic, but it cannot be strengthened by heat treatment. It is suitable for stainless steel with a slightly higher corrosion resistance and heat resistance and general strength requirements. screw.
Martensitic stainless steel
Type 410 and Type 416 can be strengthened by heat treatment, with a hardness of 35-45HRC and good machinability. They are heat-resistant and corrosion-resistant stainless steel screws for general purposes. Type 416 has a slightly higher sulfur content and is an easy-to-cut stainless steel.
Type 420, sulfur content ? R0.15%, improved mechanical properties, can be strengthened by heat treatment, maximum hardness value 53 ~ 58HRC, used for stainless steel screws requiring higher strength.
Stainless steel screw
Precipitation Hardened Stainless Steel
17-4PH, PH15-7Mo, they can get higher strength than the usual 18-8 stainless steel, so they are used for high-strength, corrosion-resistant stainless steel screws.
A-286, a non-standard stainless steel, has higher corrosion resistance than the commonly used 18-8 type stainless steel, as well as good mechanical properties at elevated temperatures. It is used as high-strength, heat-resistant and corrosion-resistant stainless steel screws, which can be used up to 650-700 °C.
Stainless steel screw
Austenitic stainless steel
The commonly used grades are 302, 303, 304, and 305, which are the four grades of so-called “18-8” austenitic stainless steel. Whether it is corrosion resistance, or its mechanical properties are similar. The starting point for selection is the production process method of stainless steel screws, and the method depends on the size and shape of stainless steel screws, and also depends on the quantity of production.
Type 302 is used for machined screws and self-tapping bolts.
Type 303 In order to improve the cutting performance, a small amount of sulfur is added to Type 303 stainless steel, which is used to process nuts from bar stock.
Type 304 is suitable for processing stainless steel screws by hot heading process, such as longer specification bolts and large diameter bolts, which may exceed the scope of cold heading process.
Type 305 is suitable for processing stainless steel screws by cold heading process, such as cold formed nuts and hexagonal bolts.
Type 309 and Type 310 have higher Cr and Ni content than Type 18-8 stainless steel, and are suitable for stainless steel screws working at high temperatures.
316 and 317 types, they both contain alloying element Mo, so their high temperature strength and corrosion resistance are higher than 18-8 stainless steel.
Type 321 and Type 347, Type 321 contains Ti, a relatively stable alloying element, and Type 347 contains Nb, which improves the intergranular corrosion resistance of the material. It is suitable for stainless steel standard parts that are not annealed after welding or are in service at 420-1013 °C.
Post time: Oct-18-2023