The origin of the name of these materials,304 is just a code for stainless steel, and has no special meaning，304 generally represents ASTM standard production, and SUS 304 represents Japanese standard production; the reason why C45 steel is called 45 is because its carbon content is 0.45%, so it is named 45 steel; The "Q" in Q235 represents the yield strength of the material. The following 235 means that the yield strength of this material is 235MPa.

By comparing the attribute values of these three materials, you can further understand:

The density of 304 is 7.93 g/cm, and the density of No. 45 steel and Q235 is the same, both are 7.85 g/cm. Mass m=pv=density x volume, so the weight of these three materials of the same volume is not different.

The yield strengths of 304, 45 and Q235 are 205 MPa, 355 MPa and 235 MPa, respectively. The yield strength is the yield limit when a metallic material yields, that is, the stress that resists minor plastic deformation. The external force greater than the yield strength will make the parts permanently fail and cannot be recovered. For example, the yield limit of Q235 is 235MPa. When an external force greater than this limit is applied, the part will undergo permanent deformation. If it is less than this, the part will return to its original state. It can be seen that 304 and Q235 have better plasticity, and their applications in sheet metal processing will be more extensive.

The hardness of 304, 45 and Q235 are 201HB, 197HB and 150HB respectively. The hardness of 304 and 45 is not very different, Q235 is slightly weaker, but there is no problem in making general parts. The price of 304 is much higher than the other two materials, and the price of 45 is higher than Q235.

The advantages and disadvantages and uses of these steel materials:

The biggest advantage of 304 is that it has its own anti-rust properties, without any surface anti-rust treatment. The surface is very beautiful after brushed, so it is often used as a decorative board. Its only drawback is that the price is too expensive. 45 After tempering, the parts have good comprehensive mechanical properties and are widely used in various important structural parts, especially those connecting rods, bolts, gears and shafts that work under alternating loads. But the surface hardness is low and not wear-resistant. Available quenching and tempering + surface quenching to improve the surface hardness of parts. Because of its moderate carbon content, Q235 has good comprehensive performance, and its strength, plasticity and welding properties are well matched. It is the most widely used.