Tempering brittleness more serious, intergranular fracture on the higher proportion of steel fracture. Steel elements of the role of high-temperature tempering brittleness is divided into: (1) high-temperature tempering brittleness of steel caused impurity elements such as phosphorus, tin and antimony. (2) in different forms, different levels of alloying elements that promote or slow down the high-temperature tempering brittleness. Chromium, manganese, nickel, silicon and the like from the promoting effect, PPGI Color Coated Prepainted Corrugated Steel Roofing Sheets and molybdenum, tungsten, titanium, etc. from the delay effect. Carbon also plays a role. General carbon steel for high temperature temper brittleness is not. Sensitive, binary contain chromium, manganese, nickel, silicon or multi-alloy steel is very sensitive to the degree of sensitivity by the type and content of alloying elements are different.
Reduce the high-temperature tempering brittleness measures are: (1) high-temperature tempering oil after rapid cooling or cold water to suppress impurity elements in the grain boundary segregation; (2) the use of steels containing molybdenum, molybdenum content increased when the steel 0.7%, the tempering embrittlement tendency is greatly reduced, which exceed this limit molybdenum steel formed a special carbide-rich, lower molybdenum content in the matrix, but the steel embrittlement tendency to increase; (3) reduce the impurity elements in steel content; (4) component of long-term work in the high-temperature tempering embrittlement Area, plus molybdenum is also difficult to prevent embrittlement, only lower impurity elements in steel to improve the purity of steel and composite aluminum and rare earth elements complemented alloying, can effectively prevent tempering brittleness. Original organization tempered steel has a significant difference in the sensitivity of the high-temperature tempering steel brittle.
Tempering of martensite tempering brittleness tissue sensitivity of the largest organizations bainitic tempering followed pearlite. The nature of high-temperature tempering steel brittle, generally considered to be phosphorus, tin, antimony, arsenic and other impurities segregate prior austenite grain boundaries, resulting in the grain boundary embrittlement results. And manganese, nickel, chromium and other alloying elements and said impurity element of grain boundary segregation to promote and increase the impurity element concentration embrittlement. And molybdenum, in contrast, phosphorus and other impurities have a strong interaction, can produce precipitates in the grain and hinder grain boundary segregation of phosphorus, reduce the temperature temper brittleness of rare earth elements and molybdenum have a similar effect. Titanium to more effectively promote the precipitation of phosphorus and other impurities in the crystal, thus weakening the grain boundary segregation of impurity elements slowed the high-temperature tempering brittleness.
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