Process performance of GCr15 steel

Process performance of GCr15 steel - 2018 11 - 24 good malleability of GCr15 steel, forging temperature range wide, reticulate carbide tendentiousness. Forging process is commonly: heating temperature of 1050 ~ 1100 ℃, the initial forging temperature 1020 ~ 1080 ℃, the final forging temperature 850 ℃, air cooling after forging. Organization for fine lamellar pearlite after forging, allow a tiny carbide network. Such organizations can not directly by normalizing spheroidizing annealing. If improper forging technology, such as finish forging temperature is too high, cold after forging speed too slow, the carbides precipitate along austenite grain boundary is obvious, the result would be a gross carbide network; And as finish forging temperature is too low, the precipitate along grain boundary carbides will join austenitic grain elongated along the deformation direction, make the carbide strip. These two types of carbide are not changed by spheroidizing annealing process, must, before spheroidizing annealing eliminated by normalizing method, so as to ensure the quality of spheroidizing annealing and give the mold good heat treatment performance. GCr15 steel quenching heating temperature generally is 900 ~ 920 ℃, the cooling speed & ge; 40 ~ 50℃/分钟。 Small die blanks can be in the still air cooling; Large die blanks can use blowing or spray cooling; Diameter & gt; 200 mm large die blanks can be cool in the hot oil and the surface temperature of 200 ℃ in air cooling. A way of cooling after formation of the internal stress is bigger, easy to crack, should immediately go to stress spheroidizing annealing or adding annealing process. GCr15 steel spheroidizing annealing process is: the heating temperature of 770 ~ 790 ℃, the heat preservation 2 ~ 4 h, 690 ~ 720 ℃ isothermal temperature, isothermal time 4 ~ 6 h. After annealing for small, uniform spheroidal pearlite, hardness of 217 ~ 255 HBW. Has the good performance can be processed. GCr15 steel hardenability is better, Oil quenching hardening critical diameter is 25 mm) , oil quenching cases obtained the depth of hardening layer close to carbon tool steel quenching. Under the condition of spheroidizing annealing organization meets the requirements, a wide range of quenching temperature overheat tend to be small, less residual austenite, quenching deformation is small, easy to obtain the stable quality of heat treatment. GCr15 steel in the condition of normal quenching and low temperature tempering also has high compressive strength, and use it to make cold extrusion convex mold have longer service life.