Based On The Manual Electricarc And Argonarc Welding Of SS400Steel Welding On Heataffected Zone Study

Manual electric arc welding and argon arc welding are two kinds of welding methods,these two kinds of welding are widely used in engineering. With the development of iron andsteel smelting,breakthrough and progress ofrolling and heat treatment technology, high strengthlow alloy steel production and use more and more widely. However, this kind of steel due tothe reduction of second phase particle problem, rough texture softening of heat affected zone,brittle crack,cold fusion zone and over heated zone and serious appear easily in the process ofwelding heat affected zone, in-depth study of the temperature field, mechanical properties andstructural transformation is an important link to improve the welding the quality of the. Theselection of manual electric arc welding and argon arc welding two welding methodsrespectively, welding experiments were conductedon SS400ultra-fine grain steelsheet4mm.Use the quenching dilatometer simulation and the heat affected zone of SS400steelorganization critical phase transition temperature and drawing SH-CCT curve determination.Through the analysis of the microstructure and hardness, when the cooling rate at0.1℃/s~20C℃/s, occurs mainly ferrite+pearlite transformation, along with the increase of cooling rate,the pearlite content increasing, and the ferrite grain decreased, hardness increased; when thecooling rate at30℃/s~80℃/s, change of shellfish bainite; when the cooling rate is greaterthan100℃/s, the emergence ofa large number of martensite.Using K type thermocouple measurement of two methods of welding heat cycle curve, bythe thermal cycle curve can be seen, manual electric arc welding and argon arc welding seamfrom two points10mm and20mm, argon arc welding of heating rate and cooling rate werelower than that of manual electric arc welding, manual arc welding is higher than the peaktemperature of argon arc welding. The temperature change range of high temperature zoneargon arcwelding is less than the manual electric arcwelding.Blind hole method is used for measuring the residual stress after welding steel plate,obtained the vertical direction of welding and welding residual stress parallel to the direction ofthe distribution curve. The experimental results show that: manual electric arc welding in a maximum of387MPa residual welding stress zone vertical direction of welding, stress iscompressive in the weld seam on both sides, distance is12mm, the maximal compressivestreSS. Parallel to the direction of welding residual stress is tensile stress in the middleposition, stress is compressive in the workpiece side, close to the edge press stress increase.The maximum tensile argon arc perpendicular to the welding direction stress is328MPa, theweld on both sides of the distance is7mm, the maximal compressive stress. Parallel to thedirection of welding residual stress on the similar curve and manual electric arc welding, argonwelding deformation is smaller than the manual arc welding.In order to distribution method for welding different research joint microstructure andmicrohardness of the transformation by welding, manual arc welding and argon arc welding of2welding methods of low alloy4mm thick high strength steel welding, shooting organizephotos, the determination of hardness, the analysis of the microstructure in heat affected zoneand micro hardness. The experimental results show that: the fusion zone of manual electric arcwelding large than argon arc welding, with widmanstatten organization, argon arc weldingorganization is mainly coarse ferrite and pearlite. The extent of coarsening organization manualelectric arc welding in the overheated zone than argon arc welding, widmanstatten percentage isfar greater than the argon arc welding, argon arc welding in the area is mainly coarse ferrite,pearlite and a small amount ofbainite, brittle manual electric arc welding in the overheated zonethan argon arc welding. Manual arc welding and argon arc welding joint hardness curve alongthe weld center symmetry, maximum hardness greater than manual electric arc welding ofargon arc welding, the weld center hardness greater than argon arc welding, manual arc weldingin HAZ hardness values greaterthan argon arc welding.