How many times have there been production problems when new coils or melts were put into production? These problems can be breaks, cracks, burrs, poor weld penetration, poor electropolished surface, and many others. Hardness tests, tensile tests, and metallographic cross sections, and review of factory test reports are common procedures for determining the source of a problem. Sometimes the source of the problem is found, but usually nothing out of the ordinary is found. In these cases, the problem lies in the composition of the steel, even if the alloy is within the specified composition range for the steel.

Description of ASTM 316 2205 904l 2B BA HL 6K 8K mirror finish stainless steel coil:

In this article, we will limit our discussion to austenitic stainless steels, although many of the comments apply to other types as well. Many problematic items are out of control and must be specified on the customer’s specification or purchase order. Don’t assume that the alloy you are buying is made from the average range of each item. Since 1988, steel mills have had a program known as “alloy chipping” that uses a minimum of alloying elements just to prevent hot embrittlement and cold rolling cracking.
Grade Design Austenitic stainless steels are designed to provide corrosion resistance in many environments, resistance to hydrogen and embrittlement at 885ºF (475ºC), good strength, good ductility and low hardness. Stainless steel in its simplest form is iron with at least 12% chromium. This is what makes stainless steel resistant to rust and allows a passive film to form. Stainless steel exists in three metallurgical states depending on composition and heat treatment: ferritic, martensitic and austenitic. These names refer to the crystal structure: ferrite is body-centered cubic, austenite is face-centered cubic, and martensite is a twisted tetragonal system, that is, a twisted face-centered cubic structure becomes body-centered.
Pure iron has a body-centered cubic shape and exists from absolute zero to its melting point. When certain elements are added, “gamma rings” or austenite are created. These elements are carbon, chromium, nickel, manganese, tungsten, molybdenum, silicon, vanadium and silicon. Among these elements, nickel, manganese, chromium and carbon are able to expand the gamma ring the farthest. It is the combination of nickel and chromium that makes austenitic stainless steels face centered cubic from absolute zero to the melting point. It is this gamma ring that distinguishes ferritic alloys from martensitic ones. The chromium content of martensitic stainless steel is very narrow, 14-18%, and must contain carbon, because only when heated in this range can pure austenite be formed, so that martensite can be obtained by quenching. Ferritic alloys have a content either below 14% or above 18%. Changing alloying elements can change the range. The most common way is to keep your carbs low.
The most common austenitic stainless steels based on the composition 18-8, 18% Cr 8% Ni. If the nickel content in steel exceeds 8%, it is austenitic, if the nickel content is lower, then it is duplex steel, that is, austenitic with islands of ferrite. At 5% nickel, the structure is approximately 50% austenitic, 50% ferritic, below 3% it becomes fully ferritic. Thus, 8% nickel is the basis for the cheapest austenitic stainless steels.
When alloying elements are added to steel, they can take a position in the main crystal. These are known as replacement alloys and the alloy remains single phase. Other elements are small enough to fit between the atoms, called interstitial elements, and the alloy remains a single phase. Other elements will combine to form their own unique crystals and form specific phases. Still others act as impurities in the alloy, known as inclusions.