Bearing steel the annealing diffusion annealing, to have stress relieving and several types of ball annealing, etc. Bearing collar forgings anneal should adopt ball annealing. Ball annealing to make the organization of uniform distribution of fine granular pearlite, to provide the best original organization annealing; Improve the plastic, reduce the hardness, facilitate cutting processing.
1. Pearlite shape, size distribution on the influence of the performance
Is the ferrite pearlite and cementite mixture, the carbon content of 0.8%. If the pearlite cementite to flake exists, is called the steel sheets. Will flake pearlite through ball annealing, cementite form a ball, then called globular pearlite. GCr15 bearing steel annealing is to get the big ball pearlite organization, and requirement is small, even distribution of fine granular. Pearlite shape, size distribution on the influence of processing performance can be discussed from the following conditions:
(1) even fines of granular pearlite, coarse crumbs, flake of than, thick flake of pearlite heat treatment temperature of heat a wide range, easy to control temperature; And the plastic good, cutting small resistance, easy to cutting processing.
(2) evenly distributed, size appropriate granular pearlite, for the following quenching provides good organization state so that quenching temperature range wide, hardened martensitic organization get small, even, not easy the creation overheating and soft point, to improve the bearing inner quality lay a good foundation.
(3) if the original organization before quenching for coarse crumbs, flake and thick flake of pearlite, the overheating sensitivity is big, the heating temperature not easy to control, hardened organization is not even, to make the work yi deformation and cracking, mechanical properties mean; In addition, flake pearlite more ball high hardness steel, plastic is poorer, cutting resistance, cutting not easy separation, make the surface roughness value Ra rise. The car parts processing accuracy is very difficult to guarantee, the original organization must be approved by is fire again after annealing treatment.



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