Steel of nickel of 0.3mm thick plating piece connect of small resistor spot welding organizes function to consider

The plating nickel steel of 3mm piece had link, use optical microscope, analyse of divide into equal parts of aircraft of electronic nicety drawing checks an instrument, considered to solder pressure of electric current, electrode and weld time the influence that to soldering contact figuration reachs constituent function. Study the result makes clear, should solder electric current is 2.

When pressure of 3kA, electrode is 3cyc for 160N, weld time, contact figuration is good, combat shear strength for 552.

1N, contact ruptures form appearance is " button " shape. Solder area of contact frit nucleus microstructure by bulky and columnar brilliant is formed, the separate out inside brilliant is acicular ferrite and organization of attrib wattle martensite, solder contact is microscopical capable person of mother of hardness prep above. 1 preface in last few years, the industrial department such as government of world each country and car, electric power, the sources of energy takes the development of fuel cell science and technology very seriously, research and development of fuel cell technology is broken through ceaselessly, the process that accelerates industrialization [1-3] . As the development of batteries industry, the housing data of batteries chooses to become crucial issue. Plating nickel steel piece learn function and treatment function with superior integrated force, and having admirable corrosion resistance, it is the batteries housing data that uses extensively at present [4, 5] . Small resistance welding is the method that the resistor heat that uses electric current to arise through workpiece interface has soldering [6] , regard a kind of important small link as the technology, apply extensively at microelectronics, MEMS and biology medical apparatus and instruments in making, if batteries, PCB board interrelates, relay, sensor and pacemaker [7] . Small resistance welding can control an element more, solder steadily quality asks to craft standard strict, to containing the akin material spot welding of film, film shares the metallurgy reaction of frit nucleus metal, because this appropriate craft parameter is right the impact of contact is bigger. The technology with batteries commonly used housing has drill rod solder, small laser beam welding, small resistance welding to wait. Drill rod solder heats rate is slow, overmuch hot input can destroy the structure of batteries interior, cause short circuit, do not use drill rod solder commonly; Tiny laser is built receive, solder place is little, affect electric performance; Use technology of small resistance welding, it is good to can satisfy contact conductivity, fight corrode, the demand with high reliability, be used extensively accordingly [2, 3] . But the research of this respect is very few still, the research that high temperature of connect of housing spot welding corrodes behavior reports [3] , the small resistor spot welding to armor plate of film of high melting point still is fumbling, film stuff makes however process of small resistor spot welding complications, the article is to ply 0.

Steel of 3mm plating nickel piece small resistor spot welding experiments, observation connect cross section form appearance, research connect is microcosmic organization and function, analyse the effect of head of butt joint of each craft parameter. The plating nickel steel that 2 experiments condition and methodological test use course rolling piece, ply is 0.

3mm, undertake spot welding. Use the profile of sample burnish of W20 metallographic sand paper, eliminate sample burr. Wipe sample surface with acetone and blow dry, of purify surface smeary. Solder equipment communicates small resistor welder for the MEA-100A of Japanese MIYACHI company, the parameter of controllable has solder electric current, beforehand force, weld time and electrode diameter. The electrode diameter that uses in experimental process is changeless, the change solders electric current, beforehand the change of force and function of connect of weld time research. Cross section of intercept of center of connect of the edge after solder, use observation of microscope of 4XB-TV convert metallographic to solder contact is different macroscopical form appearance and metallographic organize section cross section, contact uses solution of 4% nitric acid to corrode; Use INSTRON5543 profile to expect experiment machine checks the biggest dead load; Use WT-401MVD number to show microscopical what sclerometer measures cross section to go up is microscopical hardness. The organization of appearance of form of combinative welding line, metallographic, biggest dead load and contact hardness analyse the performance of spot welding connect. 3 tests result and analysis 3.

Cross section of head of butt joint of 1 craft parameter passes trial test before the influence solder of form appearance, use different craft parameter to undertake building receiving a trial to sample, every groups prepare 3 sample (× of 25mm × 5mm 0.

3mm) , measure the most greatly dead load takes its average, define soldering optimal parameter scope through contrast, pass the hardness of the metallographic organization, biggest dead load and connect, will obtain good craft parameter. Through sample macroscopical gold phasor discovers, when electrode pressure and weld time particular case falls, solder the influence of head of voltaic butt joint is shown 1 times like the graph, solder electric current (2.

1~2.

4kA) increase, current density greatens, hot input is big, the material in spot welding process can better fusion, check the generation of blemish; Electric current is too small, heat insufficient, cause not frit nucleus; Electric current is too big (> 2.

5kA) can stick caustic electrode, solder the process builds those who become material to burn caustic and splash, solder bond greatens, bring about contact pull cut force to become poor. Should solder below the circumstance with electric current and changeless weld time, the effect of head of electrode pressure butt joint is apparent also, if the graph is shown 2 times, solder pressure is too little, the interface decrescent of material, local be heated is inhomogenous, easy generation shrinkage cavity, shrinkage cavity can become crackle source, bring about the generation of crackle, influence connect is pulled cut strength; Electrode pressure is too great, impress is deeper, frit nuclear radius greatens, of contact pull cut force to reduce. Solder heat time and solder voltaic action is similar, weld time is too long bring about grain to greaten, affect contact intensity. The impact that head of butt joint of pressure of electric current, electrode, weld time solders in process of small resistance welding is very big, obtain optimal parameter through optimizing an experiment, i=2.

3kA, F=160N, T=3cyc. 3.

The microstructure of 2 connect pursues 3 for times lower the microstructure that contact solders below microscope, contact figuration is good, small resistance welding solders plating nickel steel piece welding line does not have visible defect, solder nucleus is in-house with columnar brilliant is given priority to, crisscross is arranged; Solid state metal expands because of heating, below the action of electrode pressure the metal produces plasticity to be out of shape and squeeze to board seam, brought about board seam happen become warped from, did not affect joint mechanical function; Solder nucleus and hot influence have clear plasticity link to surround solder nucleus between the area. The microcosmic organization of Nextpage mother capable person is like graph 4a, test data passes rolling processing, give priority to with grain of lumpish ferrite matrix, there is clear boundary line between grain, lump has petty carbide to distributing on ferrite grain, grain along rolling direction stretchy; Graph 4b is the welding line near bond and hot influence area, electrode electrify stops, liquid state metal begins cooling crystallization, weld junction is in liquid state metal to be in super-cooling above all, with fusing the grain of condition is off-the-peg surface partly, many form nucleus, with branch brilliant form along with medicinal powder the way with opposite heat center of Xiang Rong nucleus grows, branch brilliant is outspread all the time till each other encounter, form board the interface between, annulus of this process plasticity is accompanying frit nucleus to be brought up ceaselessly. Because weldment is ultrathin material to come loose hot rate is rapid, frit nucleus center arises without grain waiting for an axis; Graph 4c manages an organization for position of frit nucleus center, can see from inside the graph, in frit nucleus bulky and columnar brilliant mutual crisscross distributings, have inside brilliant acicular ferrite and organization of martensite of attrib wattle shape. 3.

The mechanical function of 3 connect chooses the sample with better by nature 3, take its average to come to those who evaluate sample pull trim function. 0.

Steel of 3mm plating nickel piece small resistor spot welding receives a data of mechanical function test to see subordinate list. Pull cut an experiment to rupture place affects an area in heat mostly, of contact pull clipping to crack formal edge solder all round the dot " button " shape is torn off, solder nucleus was not out of shape, if the graph is shown 5 times, the element of sample connect intensity analyses: In fast and cooling process, the organization of contact produces change, martensite reachs aggrandizement action since the tensile strength of head of occurrence butt joint; And extend in what there is combinative line in frit nucleus area, metallic plasticity is poor near spot welding bond, transfer as a result of the dimension of grain in cooling crystallization process faster, contact suffers concentration of the stress when carrying, form rupture crackle, the home that brittleness destroys. Frit nucleus brim touchs tension to cut force small, easy form crackle source, as pull those who cut force to increase crackle to be able to be in along combinative line patulous, organize near weld junction distributing inhomogenous, crystal orientaton is different, bring about contact rupture. Graph the hardness graph of 6 indication connect, can see from inside the graph, integral hardness differs apparently, the hardness of mother capable person is apparent under frit nucleus area, reach the organization between mother capable person through frit nucleus area knowable, small resistance welding the organization of frit nucleus area, the edge is columnar crystal boundary grows extend brilliant inside acicular ferrite and martensite of attrib wattle shape; Because film nickel is right,at the same time the metallurgy process of bath has certain effect, refine organization of welding line metallographic, increase acicular ferrite and first the volume amount of eutectoid ferrite is compared, improved joint microscopical hardness, brought about hardness of frit nucleus area to rise significantly thereby, drop cold-short transition temperature at the same time, raise the tenacity of contact; In frit nucleus center place hardness curve drops somewhat, corresponding a relatively low cost, this is main end crystallizes at refrigeration degree of supercooling of center of nucleus of the frit in the process is small, the content of martensite is reduced relatively, accordingly hardness has apparent reducing; The effect that suffers temperature nearly from frit nucleus is big, hardness lifts gradually near hot influence area, basically be in the carbide in cooling process little grain has action of aggrandizement of the 2nd photograph and the change that stand by the organization on weld junction, make this area hardness increases; And grain of mother capable person is bulky, it is matrix with lump ferrite, hardness on the low side. 4 last words 4.

1 use small resistance welding to 0.

Steel of 3mm plating nickel piece when undertaking spot welding, its are best craft parameter is to solder electric current 2.

3kA, solder when 3cyc of pressure 160N, weld time, solder right now contact is obtained the biggest bear the weight of force. 4.

Head of butt joint of 2 craft parameter is mechanical the influence rule of function: Solder voltaic impact is the biggest, solder pressure take second place, weld time is the least. 4.

3 frit nucleus with bulky columnar brilliant is given priority to, appear inside brilliant acicular ferrite and attrib wattle martensite, mother capable person is matrix with lumpish ferrite, increase gradually to the hardness of frit nucleus from mother capable person; Metallic plasticity is poor near bond, contact suffers concentration of the stress when carrying, easy form rupture crackle, bring about contact pull cut force to reduce. CNC Milling CNC Machining