Ejector pin of plastic mould standard component uses the organization of 65MnV steel to analyse

1 　 [document label is piled up] A [article number] 1001-4381(1999)05-0020-03The Structure Of 65MnV Steel For QuenchingEjector Pins Of Plastic DiesCHENG Yu-hang, ZHAO Jian-sheng, WU Yi-oing, CHEN Jiang-guo, WIAO Xue-liang(Huazhogn University Of Science And Technology, wugan 430074, china)Abstract: The Dependence Of Microstructure Of Newly Developed Plastic Die Ejector Pins Steel 65MnV On Quenching Temperature And Tempering Temperature Was Studied.

The Results Show That The Quenching Structure Of 65MnV Steel Is Mainly Composed Of Dislocation Martensite.

With The Increasing Of Quenching Temperature, the Structure Changes From The Composition Of Needle And Plate Martensite To Needle Martensite, the Microstructure Of Martensite Changes From Dislocation To Twin.

ε Carbide Is Precipitated In 65MnV Steel At Low Tempering Temperature.

Carbide And Precipitation Of M3C Carbide Can Be Observed At Higher Tempering Temperature of ε of The Decomposition Of.

Key Words: Whole of 　 of 65MnV Steel;ejector Pins;quenching;tempering;structure quenchs lukewarm or microtherm temper is ejector pin of standard component of domestic and international plastic mould is commonly used in adding heat treatment craft, it has the characteristic with simple processing technique, if material choice is appropriate, the performance characteristics of can contented ejector pin asks. Development of industry of foreign plastic mould is rapidder, to already forming series of ejector pin stage by stage with material, and home had be notted develop agree with ejector pin production and use relatively appropriative material, with material randommer, use 65Mn normally, 50B, t8, t12, 40Cr and 45 wait [1] , homebred ejector pin often asks because of cannot satisfying function and produce early failure, cause service life greatly under entrance ejector pin. China in grain industry college develops a success on the foundation here a kind of new-style whole quenchs ejector pin is special steel 65MnV, it is to be in what ejector pin adds in a subtle way to alloy changes elemental vanadium and be formed on the foundation of steel of commonly used 65Mn, have good integrated and mechanical performance [1] , rose than intensity with 65Mn steel photograph 10% , concussion tenacity raised 3 times, ground a gender to rise 0.

3 times. The article is right of 65MnV steel quench and the constituent change in temper process undertakes the system studies. The smelt of heating furnace of vacuum electric arc that 1 experiment method experiments to use 10kg with steel and into. Its chemistry composition expresses place to show as follows. Watch experiment learns composition with steel (The Composition Of Steel(wt%)CMnVPS0 of Wt%)Table 　 .

660.

8850.

0930.

0180.

008 　 use JSM-35C scanning electron microscope (electron microscope of SEM) and JEM100CX Ⅱ transmission (TEM) undertakes an analysis to the microstructure of 65MnV steel. Transmission report lens uses metallic film sample, the method that make appearance is: Machine tool of the cut that use a line cuts sample 0.

2 ～ 0.

The chip with large 3mm, use sand paper to grind to 0.

025mm is the following, develop the small wafer of  φ 3mm next, in report of MTP-1 double eject solution is decreased finally double gush decreases small bore a hole on Bao Yi, make the sample that can survey for TEM. Composition of double eject electrolyte is solution of 8% perchloric acid, double gush temperature is - 30 ～ - 50 ℃ , working voltage is 30 ～ 40V, working electric current is left and right sides of 20 ～ 30mA. 2 tests result and discuss 2.

Of steel of 1 　 65MnV quench the organization observes below optical microscope the low temperature of 65MnV steel quenchs the organization is organized for concealed needle martensite, martensite organization is petty, not easy observation, reason chooses scanning electron microscope to have observation. The graph shows the microstructure picture that after quenching with 900 ℃ via 800 ℃ for 65MnV steel, observes below scanning report lens 1 times. Graph of steel of 1 　 65MnV quench organization (800 × of SEM) 　 　 (A)800 ℃ quenchs; (B)900 ℃ quenchs Fig.

× of 1 　 The Microstructure Of 65MnV Steel After Quenching (SEM) 800 (　 of ℃ of;(b)quanching At 900 of ℃ of A)quanching At 800 can see from inside the graph, 65MnV steel quenchs in 800 ℃ when quench the organization is organized for concealed needle martensite. Along with quench of temperature elevatory, martensite is organized gradually by acicular become with the mixture condition of martensite of attrib wattle shape acicular martensite organization, and martensite needle becomes very bulky, and in steel not dissolve carbide dissolves ceaselessly and thick change, quench temperature lifts in the steel when 900 ℃ not dissolve carbide is almost all and deliquescent. The substructure that the graph shows the martensite in be steel 2 times to organize is followed quench the change of temperature. Can see from inside the graph, the organization when 65MnV steel quenchs via 840 ℃ is a fault martensite entirely almost, the content of twin brilliant martensite is quite little, in martensite batten piece in if graph 2a place is shown,can see a many fault is intricate. Lift when temperature when 900 ℃ , the amount of twin brilliant martensite increases gradually, graph 2b place shows the constituent body appearance of martensite of the brilliant that it is twin, this is the carbide in steel dissolves in increasing martensite contain carbon on average to measure be caused by. The dimension of martensite also is followed quench lift and increase of temperature, lift by 800 ℃ when temperature when 900 ℃ , martensite batten width by 0.

22 ～ 0.

46 μ M increases 0.

44 ～ 0.

56 μ M. Graph 2 different the martensite substructure that quenchs temperature falls 36000 × 　 (A)840 ℃ quenchs; (B)900 ℃ quenchs Fig.

36000 × of 　 of 2 　 The Sub- Microstructure Of Martensite Under Different Quench Temperature (℃ of A)quanching At 840; (Graph of 　 of ℃ of B)quanching At 900 shows the pattern that organizes for the martensite after 65MnV steel quenchs via 840 ℃ 3 times. Observe from inside the graph, the martensite in steel distributings very confused, mutual crisscross is arranged, can observe person handwriting martensite (graph 3a) and across martensite (graph 3b) . Still can see two martensite are in additionally encounter place produce violent collision, the martensite that generates first is bumped into percussion to give birth to slippage, form alternate state. Because martensite photograph changes,this is happen with wind shear form, very great shear stress arises when changing, stress concentration is caused in two martensite crossing, cause new martensite to generate, because this forms person handwriting martensite. If bump force to be able to make the martensite that forms first produces slippage greatly very much, also can make stress gets centrally flabby, form alternate form martensite. Graph steel of 3 　 65MnV the martensite configuration that 840 ℃ quench 18000 × (A) person handwriting martensite; (Fig of B) across martensite.

18000 × of 　 of ℃ of 3 　 Morphology Of Martersite In 65MnV Steel After Quenching At 840 2.

The observation that after the temper of steel of 2 　 65MnV organizes 　 TEM to quench via 840 ℃ to 65MnV steel, organizes via different temperature temper makes clear, when 180 ℃ temper, the carbide of the short ε that need shape with the petty separate out in steel (graph 4a) , did not discover the separate out of cementite. ε carbide degree of finish is 2 ～ 15nm, length is 30 ～ 140nm, maintain with matrix in all case concerns, jack maintains to concern on orientaton. Those who follow temper temperature is elevatory, carbide of the ε in steel transforms to cementite gradually, cementite content and dimension increase gradually. Graph 4b is the cementite that observes in sample of 260 ℃ temper, show strong record, degree of finish is 5 ～ 20nm, length is 80 ～ 250nm. Graph the influence that 4 temper temperature organizes to 65MnV steel 36000 × (the ε carbide of separate out of A)180 ℃ temper; (The cementite Fig of separate out of B)260 ℃ temper.

　 of conclusion of 4 　 The Dependence Of Microstructure In 65MnV Steel On Temper Temperature3 (the anneal organization of 1)65MnV steel organizes composition by petty pearlite and ferrite, pearlite piece layer span is 0.

8 ～ 1.

1 μ M. (The low temperature of 2)65MnV steel quenchs the organization is organized for concealed needle martensite, along with quench of temperature elevatory, quench organization gradually by acicular become with the mixture organization of martensite of attrib wattle shape acicular martensite organization, the substructure that martensite organizes by fault martensite transforms to twin brilliant martensite. (3)65MnV steel is when 180 ℃ temper separate out in all the carbide of the ε that need shape that the dispersion of case distributings, what ε carbide follows temper temperature is elevatory produce change or decompose, form strong record cementite. CNC Milling