Intergranular corrosion, while walking between the microcrystals of metal, the metal eventually disintegrate. It is related to chromium carbide precipitation along the joints. For it to occur, three conditions must be met: at least 0.035% carbon, sensitization by holding at a temperature of 400 to 800 degrees C, an acidic external environment with an oxidizing power between two defined limits. Pitting corrosion is usually not due to heterogeneity of material but the unintended presence of metallic dust, wet, form a battery (stainless steel fabricator). The steels surface then constitutes the anode and corrodes. There can be 2 mm thick pieces within hours. An environment that is both highly acidic and very oxidizing can produce similar effects.
The first chromium resistant steels were developed by the metallurgist Pierre Berthier, who noted their resistance to certain acids and imagined their application cutlery. However, at the time, we did not use the low rates and high carbon chromium levels commonly used in modern stainles-steels and alloys obtained then too rich in carbon, were too fragile to have a genuine interest.
Stainles-steels are steels with added chromium. In accordance with the European standard EN 10088-13, a stainles-steel is classified if it contains at least 10.5 wt% chromium and less than 1.2% carbon. The carbon content is limited to a maximum of 1.2% by mass to avoid carbures4 training (including chromium carbides which is a very stable chemical compound hungry chrome) that are harmful to material.
In 1890s, the German Hans Goldschmidt developed and patented a process called thermite which allowed to obtain carbon-free iron. Between 1904 and 1911, various researchers, including the French Leon Guillet, devised various alloys that could today be considered stainles. In 1911, German Philip Monnartz highlighted the influence of chromium alloys rate and resistance to corrosion.
Nickel is an austenite forming element, it provides an austenitic structure and therefore have sheets that are taking shape easily. High carbon content makes dipping the steels and to obtain a martensitic steels, very hard. But carbon overnight at weldability, and furthermore, it can trap the chromium and hinder the formation of passive layer. Other alloying elements, mainly metals relatively "noble" as molybdenum, titanium, copper further improve chemical resistance, especially in non-oxidizing environments.
Tungsten improves the resistance to high temperature austenitic stainles-steels. The titanium must be used at a level which exceeds four times the carbon content. It avoids tampering metallurgical structures during hot work, especially when welding where he takes the place of chromium to form a titanium carbide (TiC) before the forms chromium carbide Cr23C6 thereby preserving made the stainles-steel character avoiding depletion of chromium matrix in vicinity of carbide areas.
Niobium has a melting point much higher than titanium and has similar properties. It is used in filler metals for welding arc instead of titanium which is volatilized during transfer in arc. Silicon also plays a role in oxidation resistance, especially vis-a-vis the strong oxidizing acid (concentrated nitric acid or concentrated sulfuric acid chaud.
Like all metals, these steels can undergo a uniform chemical corrosion which attacks the surfaces evenly; one can then measure the mass lost per unit area and per unit time. Other forms of corrosion characterize austenitic stainless-steels and can be very embarrassing for use. Several approximate models were developed to predict the behavior of alloy as a function of overall composition of alloy. Grades are assigned coefficients established by experience to consider the weight of each element. For rolled products, there is the model of Andrew Pryce and giving the following equations:
The first chromium resistant steels were developed by the metallurgist Pierre Berthier, who noted their resistance to certain acids and imagined their application cutlery. However, at the time, we did not use the low rates and high carbon chromium levels commonly used in modern stainles-steels and alloys obtained then too rich in carbon, were too fragile to have a genuine interest.
Stainles-steels are steels with added chromium. In accordance with the European standard EN 10088-13, a stainles-steel is classified if it contains at least 10.5 wt% chromium and less than 1.2% carbon. The carbon content is limited to a maximum of 1.2% by mass to avoid carbures4 training (including chromium carbides which is a very stable chemical compound hungry chrome) that are harmful to material.
In 1890s, the German Hans Goldschmidt developed and patented a process called thermite which allowed to obtain carbon-free iron. Between 1904 and 1911, various researchers, including the French Leon Guillet, devised various alloys that could today be considered stainles. In 1911, German Philip Monnartz highlighted the influence of chromium alloys rate and resistance to corrosion.
Nickel is an austenite forming element, it provides an austenitic structure and therefore have sheets that are taking shape easily. High carbon content makes dipping the steels and to obtain a martensitic steels, very hard. But carbon overnight at weldability, and furthermore, it can trap the chromium and hinder the formation of passive layer. Other alloying elements, mainly metals relatively "noble" as molybdenum, titanium, copper further improve chemical resistance, especially in non-oxidizing environments.
Tungsten improves the resistance to high temperature austenitic stainles-steels. The titanium must be used at a level which exceeds four times the carbon content. It avoids tampering metallurgical structures during hot work, especially when welding where he takes the place of chromium to form a titanium carbide (TiC) before the forms chromium carbide Cr23C6 thereby preserving made the stainles-steel character avoiding depletion of chromium matrix in vicinity of carbide areas.
Niobium has a melting point much higher than titanium and has similar properties. It is used in filler metals for welding arc instead of titanium which is volatilized during transfer in arc. Silicon also plays a role in oxidation resistance, especially vis-a-vis the strong oxidizing acid (concentrated nitric acid or concentrated sulfuric acid chaud.
Like all metals, these steels can undergo a uniform chemical corrosion which attacks the surfaces evenly; one can then measure the mass lost per unit area and per unit time. Other forms of corrosion characterize austenitic stainless-steels and can be very embarrassing for use. Several approximate models were developed to predict the behavior of alloy as a function of overall composition of alloy. Grades are assigned coefficients established by experience to consider the weight of each element. For rolled products, there is the model of Andrew Pryce and giving the following equations:
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