1、And what is the difference between 304 304L?
Relatively speaking, low carbon 304 304L containing nickel, a little more, by reducing carbon welding to improve the corrosion resistance of nickel, plastic, improve the stability of the passivation increased.
Drop the carbon steel (0.03%), Low grade "called back" L castings in years.
When doing structures with 304 welding intercrystal occur, thus reduce keen welding heat affected OuDeNai corrosive, to prevent this kind of circumstance, can choose 304L, mainly used in boiler parts.

2、 What is the difference between ASTM304 and SUS304?
SASTM is the material test association (up) Testing for Materials and science of Japan's specifications, specifications, SUS Japanese Industrial association (JIS, best) stainless steel specification.
Chemical composition ASTM304 aspect is below 0.75% Si in JIS or KS is below the SUS304 1.0%.
When the material 304 production commonly meet ASTM specifications of the chemical composition and JIS, so the two specifications used in unified purposes. No problem.