304D, also known as Qingshan's QN1803 stainless steel, is indeed not the genuine 304, but it is still top-notch stainless steel. People typically agree on whether it's a 300 series stainless steel based on the international standard's Ni content. However, at this stage of steel material development, the role of nitrogen is becoming increasingly prominent. Nitriding solid solution strengthening and corrosion resistance can significantly reduce the dependence on Ni, and the addition of Mn can ensure strength. It is perfectly fine to use it as non-food-grade stainless steel products, even though 304 also comes in food-grade and non-food-grade. QN1803 as a substitute for 304 stainless steel for industrial, decorative, and construction applications is feasible.
304H stainless steel is a high-carbon variant of 304 stainless steel.
The "H" in 304H refers to high temperature; high carbon content ensures the high-temperature strength. According to GB150, austenitic steel must have a carbon content of not less than 0.04% when used above 525 degrees Celsius. Carbides are the reinforcing phase, especially with superior high-temperature strength over pure austenite.
304H stainless steel corresponds to the GB4237-2015 grade 06Cr19Ni10.
The numerical code for 304H stainless steel corresponding to the Chinese national standard GB24511-2017: S30409
30409 stainless steel, a high-carbon variant of 304, with the code number S30409 and grade 07Cr19Ni10, containing 0.04-0.1% carbon. S30409 is produced in accordance with the GB-T 24511-2017 standard, "Steel Plates and Strips for Pressure Vessels and Heat-Resistant Steels." It is primarily used in pressure vessels and other pressure-bearing equipment. The national standard grade is identical to that of 304H.
304H is a heat-resistant steel grade of 304.
Heat-resistant steel can be divided into two categories based on its properties: oxidation-resistant steel and high-temperature strength steel. Oxidation-resistant steel is also commonly referred to as non-scaling steel. High-temperature strength steel refers to steel that maintains excellent oxidation resistance and high strength at elevated temperatures. Heat-resistant steel can also be categorized by its heat treatment structure, including Austenitic heat-resistant steel, Martensitic heat-resistant steel, Ferritic heat-resistant steel, and Pearlite heat-resistant steel, among others.
Expanded Information:
Product Standards
For 304 stainless steel, the nickel (Ni) element is crucial, directly determining its corrosion resistance and value.
304 stainless steel The key elements are Ni and Cr, but yet...LimitedThese two elements. Specific requirements are outlined by product standards. Industry-standard determinations suggest that a material can be classified as 304 stainless steel if the nickel content is greater than 8% and the chromium content is greater than 18%. This is why such stainless steel is commonly referred to as 18/8. In fact, the relevant product standards provide very clear specifications for 304, with some variations for stainless steel of different shapes.
To confirm that a material is 304 stainless steel, it must meet every requirement of the product standards. If any requirement is not met, it cannot be called 304 stainless steel.
