The long axis of the nitriding process control heat treatment deformation
At present, the domestic general slender shaft (2-3 m) of the heat treatment deformation requirement is greater than 0.03 ~ 0.03 mm, according to the traditional manufacturing process is difficult to meet this requirement. After the traditional manufacturing process flow and process to improve and perfect, make long axis eventually nitriding processing deformation reached domestic advanced level in the same industry. 1, the long axis of the 38 crmoal traditional technological process and heat treatment process
Nitriding heat treatment requirements:
A. HV hardness 850 or higher, the penetration depth is greater than 0.50 mm, brittle level 1 ~ 2 level;
B. total length of 0.05 mm or less deformation.
At the beginning of the 38 crmoal long shaft production, according to the traditional manufacturing process technology and heat treatment process is worked out.
Process is as follows:
Forging stock one annealing time qualitative coarse car - stable temper - rough turning a fine car milling health trough a coarse grinding a nitride a fine grinding.
Heat treatment using secondary nitriding process.
According to GB/after nitriding T43401-1999 standard and GB/T9451-88 standard test, the result is as follows:
A. vickers hardness: surface: HV945; From the surface of 0.05 mm: HVl910; From the surface of 0.60 mm: HV348; Center: hardness HV294.
B. brittle level measurement with load vickers hardness tester HV5000g, brittle level to level 2;
C. inspect shaft length deformation quantity is 3 ~ 4 mm.
Analysis of causes of severe deformation after nitriding, mainly processing technological process is unreasonable process arrangement using traditional methods, the heat treatment process also has room for improvement. 2, improve process flow process and heat treatment process
According to the above situation, refer to a lot of relevant materials, and long axis of the manufacturing process and heat treatment process for the reasonable design, formulate measures for new process and heat treatment process.
In terms of process increases the stability after tempering and machining keyway PeiZhiJia keys, and the heat treatment nitriding process made certain changes, from the original nitriding furnace furnace cooling to 150 ℃, instead of furnace cooling to room temperature.
The improved processing procedure is as follows:
Forging stock one annealing time qualitative coarse car a stable tempering a fine car (Ⅰ) a stable keyseat - tempering a fine car (Ⅱ), coarse grinding PeiZhiJia key a nitride a fine grinding
According to GB/after nitriding T43401-1999 and GB/T9451-88 test, the result is as follows:
A. vickers hardness: surface: HV981; From the surface of 0.05 mm: HV938; From the surface of 0.60 mm: HV346; Center hardness HVl50g - 292.
B. brittle level measurement with load vickers hardness tester HV5000g, brittle level for Ⅰ level;
