Stainless steel is a solid material and not a special coating applied to regular steel to give it "stainless" characteristics. Common steels, and even other metals, are often coated or “bathed” with white metals such as chromium, nickel or zinc to protect their surfaces or give them other surface characteristics. While these baths have their own advantages and are widely used, the danger is that the coating can be damaged or deteriorated in some way, which would nullify its protective effect.

The appearance of stainless steel can, however, vary and will depend on how it is manufactured and its surface finish.

Stainless steels that contain chromium and nickel equivalent between 10.5% and 30% are called ferritic"), since they have a metallographic structure formed by ferrite "Ferrite (iron)"), and with higher contents of nickel equivalent, this will have a decreasing ferritic composition. Ferritic steels are magnetic (they are distinguished because they are attracted by a magnet). With carbon percentages lower than 0.1%, these steels They are not hardenable by heat treatment. On the other hand, steels between 0.1% and 1% in C are hardenable (they have hard martensite, since with lower percentages there is too little carbon to achieve hardening). They are called "martensitic" stainless steels, because they have in their metallographic structure, being magnetic, for highly alloyed stainless steels, pure martensitic steel (without a mixture with austenitic and ferritic) with Ni equivalent less than 18%. (0% Cr equivalent) to "13% Cr equivalent and 7% Ni equivalent", and up to 8% Cr equivalent and 0% Ni equivalent (this can be easily followed on the Schaeffler diagram of Cr-Ni equivalents).

3Cr13 stainless steel is a variant used in various applications due to its balance between hardness and corrosion resistance.[20]​.

The stainless steels they contain:.

They are called austenitic steels, since they have a structure basically formed by austenite at room temperature (nickel is a "gammagen" element that stabilizes the austenite field). They are not magnetic.

Austenitic stainless steels can be hardened by deformation, causing their metallographic structure to contain martensite (the metastably stabilized carbon in the form of gamma iron is transformed into the stable form of alpha iron and martensite, since carbon is less soluble in the alpha iron matrix, and it expels the C). They become partially magnetic (as much as the percentage of carbon has been converted to martensite), which in some cases makes it difficult to work on electrical appliances.

There are also duplex steels (20% < Cr < 30%), (5% < Ni < 8%), (C < 0.03%), not hardenable by heat treatment, very resistant to pitting corrosion and with good behavior under tension. Ferrite and austenite structure.

A small percentage of molybdenum can be added to all stainless steels to improve their resistance to chloride corrosion and other properties.

Most common commercial stainless steel alloys:

The original form of stainless steel is still widely used, engineers now have many options when it comes to different types. They are classified into different metallurgical “families”:

This distribution of metallurgical families can be easily recognized through the Schaeffler Diagram (Diagram for highly alloyed stainless steels of Chromium and Nickel equivalent, or equivalent Cr-Ni diagram).

Each type of stainless steel has its mechanical and physical characteristics and will be manufactured in accordance with established national or international regulations.

Stainless steel is classified into five different families, there are four that correspond to particular crystalline structures such as: austetine, ferrite, martensite and duplex. And as for the fifth, they are alloys hardened by precipitation altered by the environment where it is found.

Contenido

Los aceros inoxidables se utilizan principalmente en cinco tipos de mercados:.

Su resistencia a la corrosión, sus propiedades higiénicas y sus propiedades estéticas hacen del acero inoxidable un material muy atractivo para satisfacer diversos tipos de demandas, como lo es la industria médica.

Stainless steel in the medical industry

There is a diversity of chemical compositions for stainless steel, which give it particular and desired qualities; from the grade of medical implant, to the facilitation of manufacturing of surgical instruments. Among the steels used in the medical industry the following are commonly found:

Many of these can be subjected to heat treatment in order to modify their physical qualities. For example, 17-4 stainless steel can be heat treated for a certain duration in order to achieve a certain degree of hardness and thus make the object function properly for a longer time. It is important that conditions are controlled, from baking temperature and time, to the cleanliness of the oven atmosphere and the steel itself. The hardness of stainless steel can be measured on the Brinell, Rockwell or other scales.

Additionally, a passive layer can be applied to inhibit rust or reactions with some element, but this is not always the case as it is not always necessary or required, for reasons of cost or because not all stainless steels can be treated.

During World War II, the shortage of nickel led a group of scientists to look for alternatives to make stainless steel with lower nickel content. As a result, new variants were developed, including the 200 series, which were put on hold at the end of the conflict. This steel has nonmagnetic properties similar to those of 304 stainless steel, but with different characteristics in terms of corrosion resistance.

Stainless steel is a solid material and not a special coating applied to regular steel to give it "stainless" characteristics. Common steels, and even other metals, are often coated or “bathed” with white metals such as chromium, nickel or zinc to protect their surfaces or give them other surface characteristics. While these baths have their own advantages and are widely used, the danger is that the coating can be damaged or deteriorated in some way, which would nullify its protective effect.

The appearance of stainless steel can, however, vary and will depend on how it is manufactured and its surface finish.

Stainless steels that contain chromium and nickel equivalent between 10.5% and 30% are called ferritic"), since they have a metallographic structure formed by ferrite "Ferrite (iron)"), and with higher contents of nickel equivalent, this will have a decreasing ferritic composition. Ferritic steels are magnetic (they are distinguished because they are attracted by a magnet). With carbon percentages lower than 0.1%, these steels They are not hardenable by heat treatment. On the other hand, steels between 0.1% and 1% in C are hardenable (they have hard martensite, since with lower percentages there is too little carbon to achieve hardening). They are called "martensitic" stainless steels, because they have in their metallographic structure, being magnetic, for highly alloyed stainless steels, pure martensitic steel (without a mixture with austenitic and ferritic) with Ni equivalent less than 18%. (0% Cr equivalent) to "13% Cr equivalent and 7% Ni equivalent", and up to 8% Cr equivalent and 0% Ni equivalent (this can be easily followed on the Schaeffler diagram of Cr-Ni equivalents).

3Cr13 stainless steel is a variant used in various applications due to its balance between hardness and corrosion resistance.[20]​.

The stainless steels they contain:.

They are called austenitic steels, since they have a structure basically formed by austenite at room temperature (nickel is a "gammagen" element that stabilizes the austenite field). They are not magnetic.

Austenitic stainless steels can be hardened by deformation, causing their metallographic structure to contain martensite (the metastably stabilized carbon in the form of gamma iron is transformed into the stable form of alpha iron and martensite, since carbon is less soluble in the alpha iron matrix, and it expels the C). They become partially magnetic (as much as the percentage of carbon has been converted to martensite), which in some cases makes it difficult to work on electrical appliances.

There are also duplex steels (20% < Cr < 30%), (5% < Ni < 8%), (C < 0.03%), not hardenable by heat treatment, very resistant to pitting corrosion and with good behavior under tension. Ferrite and austenite structure.

A small percentage of molybdenum can be added to all stainless steels to improve their resistance to chloride corrosion and other properties.

Most common commercial stainless steel alloys:

The original form of stainless steel is still widely used, engineers now have many options when it comes to different types. They are classified into different metallurgical “families”:

This distribution of metallurgical families can be easily recognized through the Schaeffler Diagram (Diagram for highly alloyed stainless steels of Chromium and Nickel equivalent, or equivalent Cr-Ni diagram).

Each type of stainless steel has its mechanical and physical characteristics and will be manufactured in accordance with established national or international regulations.

Stainless steel is classified into five different families, there are four that correspond to particular crystalline structures such as: austetine, ferrite, martensite and duplex. And as for the fifth, they are alloys hardened by precipitation altered by the environment where it is found.

Contenido

Los aceros inoxidables se utilizan principalmente en cinco tipos de mercados:.

Su resistencia a la corrosión, sus propiedades higiénicas y sus propiedades estéticas hacen del acero inoxidable un material muy atractivo para satisfacer diversos tipos de demandas, como lo es la industria médica.

Stainless steel in the medical industry

There is a diversity of chemical compositions for stainless steel, which give it particular and desired qualities; from the grade of medical implant, to the facilitation of manufacturing of surgical instruments. Among the steels used in the medical industry the following are commonly found:

Many of these can be subjected to heat treatment in order to modify their physical qualities. For example, 17-4 stainless steel can be heat treated for a certain duration in order to achieve a certain degree of hardness and thus make the object function properly for a longer time. It is important that conditions are controlled, from baking temperature and time, to the cleanliness of the oven atmosphere and the steel itself. The hardness of stainless steel can be measured on the Brinell, Rockwell or other scales.

Additionally, a passive layer can be applied to inhibit rust or reactions with some element, but this is not always the case as it is not always necessary or required, for reasons of cost or because not all stainless steels can be treated.

During World War II, the shortage of nickel led a group of scientists to look for alternatives to make stainless steel with lower nickel content. As a result, new variants were developed, including the 200 series, which were put on hold at the end of the conflict. This steel has nonmagnetic properties similar to those of 304 stainless steel, but with different characteristics in terms of corrosion resistance.