The ageing treatment of metallic workpiece

Wei Ermu considers to discover when duralumin, the hardness after this kind of alloy quenchs is not tall, but after period of time is set below room temperature, hardness rises significantly, this kind of phenomenon is called to precipitate later sclerotic. This one discovery aroused great interest in engineering group. Subsequently people discovered a few aluminium alloy that can employ ageing treatment to undertake aggrandizement, copper alloy is mixed in succession iron radical alloy, the new aggrandizement approach that initiated to quench with general iron and steel aggrandizement has essential difference -- aggrandizement of effectiveness for a given period of time. Great majority undertakes the alloy of aggrandizement of effectiveness for a given period of time, primitive organization is by a kind of solid solution and certain metal compound place is comprised. The solubility of solid solution follows the rise of temperature and increase. Undertake quenching before ageing treatment, when heating to be in namely, make as far as possible much solute dissolve enters solid solution, it is subsequently in fast refrigeration although solubility drops, but superfluous solute has not enough time to come out from the analysis in solid solution, and fashion supersaturation solid solution. It is what achieve this one goal and undertake to quench often call solid dissolve heat treatment. Consider to confirm through relapsing for a long time, the essence of aggrandizement of effectiveness for a given period of time is from the separate out in supersaturation solid solution a lot of very petty sedimentary grain (it is metallic compound commonly, also may be the solute atom in supersaturation solid solution collects) in a lot of small areas, form the division of solute atom rich collect with a few very minor volume. When solution treatment has before ageing treatment, heat temperature must be controlled strictly, so that make dissolve of solid of ground of utmost of solute nuclear energy arrives in solid solution, do not cause alloy happening to fuse again at the same time. A lot of aluminium alloy solution treatment heat only 5 ℃ control the deviation with concessional temperature. Have artificial ageing treatment, must control strictly heat temperature and heat preservation time, ability gets comparative ideal aggrandizement result. Section effectiveness for a given period of time is used sometimes in production, namely preexistence room temperature or more tallish than room temperature temperature issue heat preservation for some time, fall in higher temperature next again heat preservation period of time. Make the result with can get better sometimes so. The meeting when steel of martensite effectiveness for a given period of time quenchs produces constituent change, form martensite. Martensite is solid solution of a kind of supersaturation. This kind of steel also can use ageing treatment to undertake aggrandizement. After plasticity of mild steel cold conditions is out of shape, period of time is set below room temperature hind, intensity rises, plasticity is reduced, this kind of phenomenon calls mechanical effectiveness for a given period of time. The dimension in be being used for a long time to remove narrow measure or mould, part, appearance happening changes, often be after microtherm temper (℃ of 150-250 of microtherm temper temperature) before finish machining, heat workpiece to 100-150 ℃ afresh, hold 5-20 hour, this kind makes the processing of a quality to stabilize nicety, call effectiveness for a given period of time. To ageing treatment having in microtherm or the rolled steel component part that use load condition to fall, in order to eliminate leftover stress, stabilize rolled steel organization and dimension, particularly important. CNC Milling