The research of welding line of cold welding of steel of a kind of new-style tool

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Summary: Use scanning report lens (lens of report of SEM) , transmission (the method such as TEM) and X ray diffraction studied the microcosmic organization of welding line of cold welding of steel of a kind of new-style tool, think to join strong carbide element to be able to acquire the cold welding welding line in grain of distributinging carbide of the dispersion on matrix of low carbon martensite, hardness of this welding line tall, tenacity is good, can satisfy the tool steel demand to wearability and crack resistance at the same time. Because 1 foreword is cold make mould, metallurgy spare parts (like roller) wait to need to bear when the job tremendous hand inning changes stress and attrition action, because surface of this requirement component is in,have taller hardness (58 ～ 62HRC) , good wearability while have better tenacity. Component part material chooses steel of high grade tool commonly, and pass strict exterior heat treatment. But abominable working requirement often brings about occurrence crackle of component part surface, local even fall off. These component part cost are high, if whole discard as useless, will cause huge pecuniary loss. Compare with photograph of component part whole, its blemish dimension is general and lesser, if use proper method to have repair, can reduce manufacturing cost significantly. Solder v rehabilitate is to lengthen component part to enlist in army namely a kind of of time effective method. At present material of commonly used v welding line is Cr-Mo-W alloy department, use meshy carbide and tall carbon martensite to raise the hardness of industry pattern and wearability. But the hardness with industry pattern extremely fast face and brittleness make its solderability poor, solder to avoid crackle, the warm-up before needing solder 500 ℃ of 300 ～ () of the heat treatment after still needing to undertake solder sometimes, extreme difference of this to the rehabilitate of pattern of a few large project character craft feasibility, restricted the project application of v rehabilitate law badly, the cold welding that urgent need studies a kind of craft is simple repairs a method. To realize the cold welding of tool steel, divide outside adopting the technology measure that drops welding stress, crack resistance must be reached in the tenacity that assures to welding line increases while welding line hardness reachs wearability. The author experiments through v and use scanning report lens (lens of report of SEM) , transmission (the method such as TEM) and X ray diffraction is right the microcosmic organization of welding line of a kind of new-style cold welding undertook study. 2 v experiment and check check test data: The Ti-Nb-V-Re-Cr alloy that employs tall carbon is, transfer through welding rod coating C and alloying element, alloy of iron of metallic Nb, Ni, titanium, vanadium iron, ferrochrome, black lead and Re-Si, Re-Mg is joined in coating; Using CaO-CaF2-TiO2 broken bits is, slaggy alkalinity B=1.

3 ～ 1.

4; Use Ø3.

The H08A solder core of 2mm, welding rod of the suppress on besmear machine is pressed in TL-25 welding rod. Test equipment reachs a program: Use abstain welding rod to be in sample of metallographic of v of 9Cr2Mo roller surface, solder 150A of voltaic I=130 ～ , the temperature between the layer is less than 35 ℃ ; Cut with machine of emery wheel cut below water-cooling condition take sample. Use lens of JXA-840 scanning report (bougie of SEM) , electron (lens of report of transmission of spectrometer of fluorescence of ray of EPMA) , 3080E X, H-80 (diffractive appearance of ray of TEM) and D/max-RC X undertakes to sample microcosmic organization composition is analysed. With ZB-28 concussion experiment machine is made pound an experiment without breach, with SEM observation breaks appearance of degree of lip-rounding. Undertake in the surface of roller of 9Cr2Mo cold rolling of Ø200mm blemish is repaired and undertake examining. 3 tests result and analysis express 1 welding line main element content (quality percentage, content of %) element CTiNbVCrNiMo 0.

880.

641.

182.

181.

431.

30.

The welding line bases that bases of 25 welding line measures by spectrometer of X ray fluorescence sees a table 1. By the watch 1 knowable, spectrometer of X ray fluorescence is measured so that welding line is tall carbon multivariate alloy system, and tall carbon is the foundation that assures welding line hardness and wearability. Nb, Ti, V forms an element for strong carbide, easy form MC carbide, when content is higher but by the separate out in liquid state metal carbide is born first. The tall hardness of MC carbide (TiC: HV3200, nbC: HV2400, VC: HV2094) is helpful for raising welding line hardness and wearability; In the meantime, unripe carbide distributings first even, be helpful for improving material tenacity. Cr, Mo is in strong carbide element, but when coexisting with Ti, Nb, V, cr, Mo basically has effect of solid dissolve aggrandizement, aggrandizement matrix, and Mo to refining grain, improvement material tenacity also has certain effect. The main effect of Ni is solid dissolve aggrandizement, improvement tenacity. Fluorescent spectrometer still measures X ray welding line is mediumly to add element having Re, the purpose is to use Re oxide to offer form nucleus core for carbide, the dispersion of stimulative carbide distributings. Graph the result of 1 X ray diffraction that is welding line sample, welding line material is main by α - composition of Fe and NbC, TiC. The graph shows the distributinging pattern of the carbide in be welding line 2 times, by visible carbide amount is much in the graph and show grain shape to distributing equably. Electronic bougie and result of electronic diffraction test make clear, the compound carbide that the carbonization owner in welding line wants to be NbC, TiC, VC or Nb, Ti, V (Nb, ti, v)C. Graph 1 graph 2 graphs the 3 TEM photographs that organize for welding line matrix, knowable matrix is martensite of typical attrib wattle shape. Contain carbon as a result of martensite of attrib wattle shape the amount is small, substructure is a fault of high density, have good integral performance, because this is helpful for,improve welding line tenacity. Can obtain mild batten martensite in tall carbon welding line, with a large number of carbide inchoate form about. Content of the Nb in welding line, Ti, V is high, in liquid state frit drips or with C union forms a large number of even carbide in bath, make the carbolic content in austenite matrix is reduced, avoid to form the martensite of brilliant of tall carbon twin of brittleness thereby. On the other hand, matrix contains what carbon measures to reduce also reduced the separate out of meshy proeutectoid carbide after welding line is caky, those who reduced pair of matrix cut apart action. Graph 3 graphs 4 watches sample of 2 welding line pounds toughness (α K, experiment of concussion of 12345 α K5251564952 and welding line of fracture surface observation do not have J/) number result of breach concussion test sees a table 2, appearance of fracture surface form sees a picture 4. By the watch 2, graph 4 knowable welding line pound toughness on average to amount to 52J/ , fracture surface is fracture surface of apparent shape of nest of pliable but strong, show welding line tenacity is better. Blemish repairs an experiment to be ground with horn opportunity is right blemish of 9Cr2Mo roller surface undertakes nap, dimension of the blemish after nap is Ø30mm about, deep 8 ～ 10mm. Use cold welding craft to undertake blemish repair, the temperature between the layer is 35 ℃ about, after each solder, undertake hammer is attacked instantly in order to eliminate stress, in order to achieve improvement grain configuration, eliminate casting condition blemish and the goal that relieve welding stress. Solder hind undertakes magnetic particle flaw detection, welding line and hot influence area did not discover flaw. Welding line hardness is 56 ～ 60HRC, the exterior hardness that is close to 9Cr2Mo mother capable person (60 ～ 61HRC) . Experiment of 4 conclusion v and detect the analysis explains: Use strong carbide element to be able to obtain the carbide particle of dispersion in welding line of tool steel cold v, can raise the hardness of welding line and wearability apparently; The matrix of martensite of shape of low carbon batten that obtains in welding line at the same time is helpful for increasing the tenacity of welding line and crack resistance. Alloy of new-style tall carbon Ti-Nb-V-Re-Cr fastens cold welding welding line to be able to satisfy the requirement that industry pattern cold welding repairs, cold welding technology is simple and practical, popularize easily. CNC Milling CNC Machining