The choice of quenching and tempering temperature

The choice of quenching temperature ( 1) If used when parts of the same grade of steel quenching cooling ability of cooling agent ( Water with sodium hydroxide water quenching and oil quenching diesel) Temperature should be lower limit, take ceiling (conversely 2) Large cross-sectional area need hardening quenching temperature shall be take limit, and even can be slightly higher, such as the sectional area is lesser, should take the lower limit. ( 3) Deformation or easily quenching crack generating artifacts should take lower limit, in order to prevent deformation and cracking thin carbon steel can try quenching oil, special spinning factory of 3 m/m thin pieces with quenching oil. ( Whether it is 45 steel or T10 steel) ( 4) Only ask surface wear resistance without hardening ( Cold work die) Take the lower limit, carburization workpiece can also drop some more. ( 5) Residency artifacts required hardness shall be lower limit. ( 6) Salt bath furnace speed, less uniform, small deformation, decarburization and short heating time limit, box-type furnace heating time should take lower limit. ( 7) Retreat quenching workpiece ( Big must after annealing or high temperature tempering) The lower limit should be taken. ( 8) High red hardness requirements artifacts should take upper limit. ( 9) Microstructure is ball quenching should take ceiling light body, flake quenching light body should take the median, dot pearlite should take lower limit. ( 10) Workpiece size expansion point requirement should take upper limit. Asked the size smaller than should take lower limit. ( 11) Easily quenching crack of 45 steel in range of critical dimension should take lower limit. Had better use the temperature quenching; There are special research and reports, but we are using 770 - 780 ℃ quenching. The choice of tempering temperature ( 1) Strong cooling of quenching and tempering for ceiling. Grouping quenching isothermal quenching take lower limit. ( 2) Have self tempering phenomenon or possible self tempering should take lower limit. ( 3) Packing ( Us) Than the (using the Us) To be a little higher temperature. ( 4) Fan and uniform temperature should take the lower limit of pit type furnace, tempering should take salt furnace limit. ( 5) Oil of low temperature tempering temperature is moderate, the furnace should be lower limit. ( 6) Measured after quenching hardness low tempering should take lower limit. ( Refers to the carbon steel and low alloy steel, high alloy steel, the other for BieLun)