The quenching temperature is mainly determined according to the critical point of the wear resistant lining of high chromium cast iron.Subeutectoid steel is usually heated to 30~50℃above Ac3, while eutectoid steel and hypereutectoid steel are heated to 30~50℃above Ac1, and in some cases to 50 ~ 70℃above ^, as shown in the figure.If the quenching heating temperature of ᱟᱹᱰᱤ ᱠᱚᱢ ᱠᱷᱚᱱ ᱠᱚᱢ, ᱟᱨ ᱚᱱᱟ ᱫᱚ ᱵᱟᱝ ᱠᱟᱱᱟ, ᱚᱱᱟ ᱛᱮ, ᱱᱚᱶᱟ ᱫᱚ ᱟᱹᱰᱤ ᱠᱚᱢ ᱜᱮᱭᱟ, ᱚᱱᱟ ᱛᱮ, ᱱᱚᱶᱟ ᱫᱚ ᱟᱹᱰᱤ ᱠᱚᱢ ᱜᱮᱭᱟ, ᱚᱱᱟ ᱫᱚ ᱵᱟᱝ ᱠᱟᱱᱟ, ᱚᱱᱟ ᱫᱚ ᱵᱟᱝ ᱠᱟᱱᱟ, ᱚᱱᱟ ᱛᱮ, ᱱᱚᱶᱟ ᱫᱚ ᱵᱟᱝ ᱠᱟᱱᱟ ᱡᱮ ᱚᱱᱟ ᱫᱚ ᱵᱟᱝ ᱦᱩᱭᱩᱜ ᱠᱟᱱᱟ, ᱚᱱᱟ ᱫᱚ ᱵᱟᱝ ᱵᱩᱡᱷᱟᱹᱣ ᱟᱠᱟᱱᱟ. austenite grain will be significantly larger, thus damaging the properties after quenching.The eutectoid steel was heated above Ac1 at 30 ~ 50℃.After quenching, only a few residual austenite particles were found in vitro, and the structure was small carbide particles evenly distributed on the lamellar martensite matrix.Such tissues have high hardness, good wear resistance and relatively low brittleness.The quenching temperature of hypereutectoid steel cannot be lower than that of Ac1, because the steel has not been austenitized at this time.When heated to a temperature slightly higher than the temperature, the pearlite completely transforms into austenite and a small amount of cementite dissolves into austenite.The austenite grains were fine and the carbon mass fraction was higher than that of eutectoid.If the temperature continues to rise, the secondary STE ᱫᱚ ᱟᱹᱰᱤ ᱜᱟᱱ ᱜᱞᱩᱠᱚᱡᱽ ᱠᱟᱱᱟ, ᱚᱱᱟ ᱫᱚ ᱟᱹᱰᱤ ᱠᱚᱢ ᱜᱮᱭᱟ, ᱚᱱᱟ ᱛᱮ, ᱟᱨ ᱚᱱᱟ ᱨᱮᱭᱟᱜ ᱚᱨᱡᱚ ᱫᱚ ᱟᱹᱰᱤ ᱠᱚᱢ ᱜᱮᱭᱟ, ᱚᱱᱟ ᱫᱚ ᱟᱹᱰᱤ ᱠᱚᱢ ᱜᱮᱭᱟ, ᱟᱨ ᱚᱱᱟ ᱨᱮᱭᱟᱜ ᱚᱨᱡᱚ ᱫᱚ ᱟᱹᱰᱤ ᱵᱟᱹᱲᱛᱤ ᱠᱟᱹᱢᱤ ᱠᱚ ᱠᱚᱢ ᱞᱟᱹᱜᱤᱫ ᱠᱟᱱᱟ᱾ {᱒.᱕} \\ ᱥᱟᱹᱨᱤ ᱜᱮ ᱨᱤᱯᱷᱞᱮᱠᱴᱚᱨ᱾
Therefore, the quenching heating temperature of hypereutectoid steel is not suitable to be too much higher than Ac1, and heating to the temperature of fully austenitized Acm or above is even more inappropriate
