321 and 304 Stainless Steel Sheets
304 and 321 are austenitic stainless steel, the appearance and physical properties are very similar, only the chemical composition of a slight difference:
First of all, 321 stainless steel requires a trace amount of titanium (Ti) elements (according to ASTM A182-2008 standard provisions of its Ti content should not be less than the carbon (C) content of 5 times, but not more than 0.7%; 321 has a carbon (C) content of 0.08%) and 304 does not contain titanium (Ti).
Second, the nickel (Ni) content requirements are slightly different, 304 is between 8% and 11%, and 321 is between 9% and 12%.
Third, the requirement for chromium (Cr) content is different, 304 is 18% to 20%, and 321 is between 17% and 19%.
So you can use the metal material analyzer or chemical analysis of the method to test the composition of these two materials and make judgments.
321 and 304 belong to 300 series of stainless steel, they have little difference in corrosion resistance. But in the heat of the 500-600 degree of industrial and mining, most of the use of 321 materials. And abroad also developed a kind of heat resistant steel, called 321H. Its carbon content is slightly higher than 321 materials, similar to the domestic 1Cr18Ni9Ti. Adding an appropriate amount of Ti elements in stainless steel to improve its resistance to intergranular corrosion. This is due to the beginning of the production of stainless steel, due to smelting technology is not high, can not reduce the content of carbon in the steel, and thus can only be taken to add other elements to achieve the purpose of. With the progress of technology, a variety of stainless steel with low carbon and ultra low carbon has been produced, therefore, 304 materials are widely used. And at this time 321 or 321H or 1Cr18Ni9Ti in the thermal performance of the characteristics on the show. 321 should be 0Cr18Ni10Ti, 321 is based on the 304 plus Ti to improve intergranular corrosion tendency. 304 stainless steel is one kind of universal, which is widely used to produce good performance (corrosion resistance and formability) equipment and parts.
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