Brand : QD Name : 304 Mushroom head self-tapping screw Material : 304 stainless steel Surface treatment : stainless steel whitening Packing plastic bag carton Dimensions such ：as M2.9*6 denote thread diameter*screw length
The parameters are for reference only. Take the actual measurement as the criterion, mind taking cautious pictures!
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Detection of Thread Pass Gate
Standard head cross groove
Question: What are the grades of stainless steel? Answer: Stainless steel is usually divided into martensitic steel, ferritic steel, austenitic steel and austenitic ferrite according to its structure. (duplex) stainless steel and precipitation hardening stainless indium, etc. In addition, it can be divided into chromium stainless steel and Chromium-Nickel Stainless Steel according to their composition. Steel and chromium manganese nitrogen stainless steel, etc. Brand 200 Series: Chromium-Manganese-Nickel Austenitic Stainless Steel 300 Series: Chromium-Nickel Austenitic Stainless Steel Stainless steel 304: 18/8 stainless steel, which is commonly used in today's society. GB is 0Cr19Ni10. Question: Is it real 304 stainless steel? Answer: Very sure to tell you, each is 304 stainless steel, can be used in screw material requirements are very high. The place will not rust. It can be tested by 304 stainless steel or by professional organizations. Identify, such as false package replacement! Q: Why does 304 stainless steel have magnetism? Answer: Because stainless steel is divided into austenite, martensite, ferrite duplex stainless steel and so on, austenite is also the most used. The most widely used stainless steel, austenite is nonmagnetic or weakly magnetic, while ferrite and martensite are magnetic because A small amount of martensite or ferrite will appear in Austenite 304 stainless steel due to component segregation or improper heat treatment during smelting. Weak magnetism will appear in 304 stainless steel. Q: What is the difference between 201 stainless steel and 304 stainless steel? Answer: The common stainless steel in the market are 201 stainless steel and 304 stainless steel. The main difference is the rust resistance of 304 stainless steel. Stamping performance is much better than acid resistance in 2010, but relatively strong, generally used in complex environments. Fang. The 201 carbon content is higher, and easy to rust in water, generally used in stainless steel quality requirements are not high places. So the price is cheaper than 304. 304 is recommended. Q: What is heat treatment? Answer: Heat treatment is an important method of metal processing, which aims to improve the properties of steel. Technological properties). The heat treatment process of steel is characterized by heating the steel to a fixed temperature, heat preservation and a fixed time. Then, cooling at a certain cooling rate. Through this process, the properties of steel are changed.
Measuring with standard vernier calipers, screw is a standard part, do not measure with tape ruler, student ruler, easy to make mistakes.
Positive and negative tolerances can be accurate to 0.01 mm and the error range of positive and negative tolerances is about 1-2 mm.