The heat treatment craft of 20Mn2 car tyre chain is improved

Car tyre chain is to install a kind of on car tire annular chain, basically use at travel of car snow day to prevent slippery, install complete travel in order to ensure, it is the necessary tool of travel of car of region of winter Gao Han, because of wear-resisting of this requirement tyre chain and do not rupture, namely chain must have good wearability and obdurability. As the people buildup to safe consciousness. The use report of car tyre chain is wider and wider. It is good that 20Mn2 steel shows performance as a result of cementite and temper by dipping in water, have admirable wearability especially, reason is divided outside be being used at producing a heavy chain, still be floated be used at producing the tyre chain of heavy load van by the factory. Plant with some below tyre chain of wide abundant of heavy load goods is exemple, empty dimension is 12mm × 42mm inside its sheet annulus, line means is 7mm. Technical requirement: Cementite layer is thick 0.

25 ～ 0.

35mm, exterior hardness > 54HRC, core hardness > 40HRC, attack pull test value to not be less than 30kN. General plant uses the heat treatment technology that the graph shows 1 times mostly. 1. The technology that improves around compares the advantage expression of afore-mentioned craft to be: To lukewarm outfit furnace, after heat preservation cementite direct water temper by dipping in water, manufacturing rhythm is fast, cycle is short, be helpful for raising manufacturing labor rate. And Xiaozuzhi is in is: Although ooze layer ply, surface and core hardness achieve a requirement, but attack when helping a test, achieve 30kN hard, easy generation ruptures when tyre chain Zai Yi is bigger and cannot use, retreat goods, exchange goods to often have happen, bring adverse effect to the enterprise. Apparent, the heat treatment technology that the graph shows 1 times puts the emphasis in assure exterior hardness and wearability to go up, and ignore somewhat to core obdurability. Accordingly, must undertake improvement to heat treatment craft. With the graph 1 craft photograph is compared, the heat treatment craft after improving (2) seeing a picture is like next characteristics: (1) drops cementite temperature, shorten cementite time, be helpful for preventing grain to increase, improve mechanical performance. (2) is reduced quench temperature. The dump after cementite 30min drops in temperature, kerosene still drips by regular dose in this phase, assure to decarbonization does not oxidize when dropping in temperature, still can rise to diffuse at the same time action, enlarge ooze layer deepness (30min of this craft cementite time is opposite shorter) ; Reduce quench temperature, still can reduce leftover austenite to measure, reduce brittleness thereby. , (3) raises temper temperature. In changing microtherm temper to be lukewarm temper, raise chain tenacity. (Integral performance gets 4) be improved significantly. Hardness of ply of the layer that divide ooze, surface and former technology are same outside, core hardness slants floor level (in the) inside limits of 40 ～ 44HRC, attack pull test value to be able to achieve 30kN above. (5) manufactures efficiency and do not have drop apparently. Classics actual measurement. Cycle of two kinds of craft comparatives basically, do not have apparent effect to manufacturing efficiency. 2. After craft of epilogue heat treatment is improved, made sure chain has taller wearability not only, and from go up at all in solving chain to use rupture problem, the client is very satisfactory. CNC Milling