5 hours, follow time to lengthen, nitrogen changes a deepness to increase very slow. 2, soft nitrogen changes an organization and soft nitrogen to change a characteristic: After steel is changed via soft nitrogen, the surface is the outerest can obtain a few micron to come the white bright layer of a few micron, it is by ε photograph, γ ` photograph and nitric cementite Fe3 (C, n) place composition, the diffusion layer that second layer is, it basically is by γ ` photograph and ε photograph are comprised. Soft nitrogen changes have the following characteristic: (1) processing temperature is low, time is short, workpiece is out of shape small. (2) does not suffer steel to plant limitation, steel of carbolic steel, pattern of low-alloy steel, industry, stainless steel, cast-iron reach iron radical pink not metallurgy material all can undertake soft nitrogen changes processing. The exterior hardness after workpiece is changed via soft nitrogen and nitrogen change craft and material to concern. 3, the fatigue strength that can show touchdown to improve work, wearability and corrosion resistance. Still have below dry attrition condition fight abrade and fight occlusive wait for function. 4, because soft nitrogen changes a posture of nonexistent brittleness ξ , reason nitrogen changes the tenacity with be had the layer is hard and certain, flake not easily. Accordingly, in producing at present, soft nitrogen turns wide already application at mould, measure, cutting tool (be like: High-speed steel cutting tool) wait, the processing of the wear-resisting workpiece such as cylinder bushing of crankshaft, gear, gas, mechanical structural member. CNC Milling
To shorten nitrogen changes cycle, make nitrogen changes craft not to accept the restriction that steel plants, in in recent years the development on technology base is changed in former nitrogen soft nitrogen is changed and ionic nitrogen changes chemical industry of two kinds of new nitrogen art. Soft nitrogen is changed is the microtherm nitrogen carbon that gives priority to with nitriding essentially in all ooze, the azotic atom infiltration of steel while, still have a few carbolic atom infiltration, its handle result and general gas nitrogen to change photograph comparing, ooze layer hardness relatively nitrogen is changed low, brittleness is lesser, reason calls soft nitrogen to change. 1, soft nitrogen changes methodological cent to be: Aeriform soft nitrogen is changed, liquid soft nitrogen is changed reach solid soft nitrogen to change 3 kinds big. The application in domestic production is the at present widest is aeriform soft nitrogen is changed. Aeriform soft nitrogen is changed is microtherm nitrogen, carbon undertakes in containing atmosphere of atomic of active nitrogen, carbon in all ooze, commonly used in all ooze medium has gas of amine of acyl of urea, armour, ammonia and 3 alcohol amine, they change temperature to allot unripe pyrolysis to react in soft nitrogen, produce atom of active nitrogen, carbon. Atom of active nitrogen, carbon is absorbed by workpiece surface, through diffusing infiltration workpiece surface layer, obtain the azotic carbon that gives priority to with nitrogen thereby in all ooze layer. Aeriform soft nitrogen changes temperature ℃ of commonly used 560-570, because the nitrogen below this temperature changes a hardness,be worth highest. Nitrogen changes time to often be 2-3 hour, because exceed 2.