About the characteristics of stainless steel (304, 316)?

Stainless steel mainly has three materials: 304M, 316, and 304HC. What are their respective chemical compositions? What is the relationship between this chemical composition and stainless steel properties? What special properties do they each have? Let's do a brief introduction.

(1) The three materials are all 300 series austenitic stainless steel, and their chemical composition is as follows:

(2) The relationship between the main chemical composition and the properties of stainless steel.

1. Carbon C can increase hardness and strength, and excessive content will reduce its ductility and corrosion resistance

2. Chromium Cr can increase corrosion resistance, oxidation resistance, refine grain size, increase strength, hardness and wear resistance

3. Nickel Ni can increase high temperature strength, corrosion resistance and reduce the rate of cold work hardening

4. Molybdenum Mo increases the strength and has excellent corrosion resistance to oxides and seawater

5. Copper Cu is conducive to cold forming and reduces magnetic properties

(3) Other properties of the material

1. The above materials are non-magnetic in normal state. 304M is slightly magnetic after cold working (about 1.6u-2.0u); 304HC is magnetic (about 1.01u-1.6u); 316 material is less than 1.01u after cold working.

2. Each material has good ductility and is easy to be cold-formed, and its tensile strength and yield strength can all meet the requirements. (Ts tensile strength min 700N/mm, Ys yield strength min 450N/mm)

(4) Conclusion

1. The three materials of 304M, 304HC and 316 are currently one of the most widely used materials for 300 series austenitic stainless steel. The obvious difference between the materials is: the magnetic properties of the material after cold working are 316<>< 304m.="" compared="" with="" 304m="" and="" 304hc,="" the="" 316="" material="" is="" resistant="" to="" chemical="" corrosion,="" pitting="" corrosion="" resistance="" and="" seawater="" corrosion="">

2. In short, the characteristics of stainless steel standard parts are corrosion resistance, beautiful appearance and hygiene, but their strength and hardness are equivalent to carbon steel (6.8 grade) under normal circumstances, so stainless steel products should not be hit, beat, and pay attention to maintain their surface finish and accuracy. In addition, the force cannot be applied casually like the use of carbon steel products, and the force cannot be too large. At the same time, due to the good ductility of stainless steel, the steel chips generated during use are easy to stick to the tooth level of the nut, which increases the friction force and easily leads to locking. , and the use of carbon steel will fall even if the iron filings are generated, and it is not easy to lock up compared to stainless steel.