There are many names for bolts, and each person's name may be different. Some people call them screws, some call them bolts and nails, and some call them fasteners. Although there are so many names, the meaning is the same, they are all bolts. Bolt is a common term for fasteners. A bolt is a tool that utilizes the physical and mathematical principles of the oblique circular rotation and friction of an object to gradually tighten the mechanical components of the object. 
Bolts are indispensable in daily life and industrial production manufacturing, and bolts are also known as the rice of industry. It can be seen that bolts are widely used. The application scope of bolts includes: electronic products, mechanical products, digital products, power equipment, and electromechanical mechanical products. Bolts are also useful in ships, vehicles, hydraulic engineering, and even chemical experiments. Anyway, bolts are used in many places. Precise bolts used in digital products. Micro bolts used for DVDs, cameras, glasses, clocks, electronics, etc; General bolts for television, electrical products, musical instruments, furniture, etc; As for engineering, construction, and bridges, large bolts and nuts are used; Transportation equipment, airplanes, trams, cars, etc. are used with both large and small bolts. Bolts bear important tasks in industry, and as long as there is industry on Earth, the function of bolts will always be important.

From the perspective of classification, stainless steel can be divided into austenitic stainless steel and martensitic stainless steel. 304 stainless steel is the original steel grade 0Cr18Ni9 in China, which is an austenitic stainless steel. Not all stainless steel bolts are non magnetic, as long as pure austenitic stainless steel bolts are non magnetic. It has occurred that standard weights made of austenitic stainless steel bolts have magnetism, and a useful way to eliminate magnetism is through solid solution heat.
Among the components of stainless steel, there are many valuable alloy components, which are usually more expensive than martensitic stainless steel bolts. Austenitic stainless steel bolts are used for various factors with magnetism, which cannot be explained as a change in quality. They can be determined by analytical chemistry and metallographic examination.