【正文】 未來(lái)的焊接工藝，一方面要研制新的焊接方法、焊接設(shè)備和焊接材料，以進(jìn)一步提高焊接質(zhì)量和安全可靠性，如改進(jìn)現(xiàn)有電弧、等離子弧、電子束、激光等焊接能源；運(yùn)用電子技術(shù)和控制技術(shù)，改善電弧的工藝性能，研制可靠輕巧的電弧跟蹤方法。在近代的金屬加工中，焊接比鑄造、鍛壓工藝發(fā)展較晚，但發(fā)展速度很快。采用焊接工藝能有效利用材料，焊接結(jié)構(gòu)可以在不同部位采用不同性能的材料，充分發(fā)揮各種材料的特長(zhǎng)，達(dá)到經(jīng)濟(jì)、優(yōu)質(zhì)。焊接的密封性好，適于制造各類容器。角接頭承載能力低，一般不單獨(dú)使用，只有在焊透時(shí)，或在內(nèi)外均有角焊縫時(shí)才有所改善，多用于封閉形結(jié)構(gòu)的拐角處。丁字接頭上未焊透的角焊縫工作特點(diǎn)與搭接接頭的角焊縫相似。一般來(lái)說(shuō)，搭接接頭不適于在交變載荷、腐蝕介質(zhì)、高溫或低溫等條件下工作。在交變、沖擊載荷下或在低溫高壓容器中工作的聯(lián)接，常優(yōu)先采用對(duì)接接頭的焊接。厚度不同的兩塊鋼板對(duì)接時(shí)，為避免截面急劇變化引起嚴(yán)重的應(yīng)力集中，常把較厚的板邊逐漸削薄，達(dá)到兩接邊處等厚。坡口形式有單面施焊的坡口和兩面施焊的坡口。對(duì)接接頭焊縫的橫截面形狀，決定于被焊接體在焊接前的厚度和兩接邊的坡口形式。被焊接體在空間的相互位置稱為焊接接頭，接頭處的強(qiáng)度除受焊縫質(zhì)量影響外，還與其幾何形狀、尺寸、受力情況和工作條件等有關(guān)。重要產(chǎn)品焊后都需要消除焊接應(yīng)力，矯正焊接變形。這就需要調(diào)整焊接條件，焊前對(duì)焊件接口處預(yù)熱、焊時(shí)保溫和焊后熱處理可以改善焊件的焊接質(zhì)量。焊縫的兩側(cè)在焊接時(shí)會(huì)受到焊接熱作用，而發(fā)生組織和性能變化，這一區(qū)域被稱為熱影響區(qū)。釬焊是使用比工件熔點(diǎn)低的金屬材料作釬料，將工件和釬料加熱到高于釬料熔點(diǎn)、低于工件熔點(diǎn)的溫度，利用液態(tài)釬料潤(rùn)濕工件，填充接口間隙并與工件實(shí)現(xiàn)原子間的相互擴(kuò)散，從而實(shí)現(xiàn)焊接的方法。同時(shí)由于加熱溫度比熔焊低、加熱時(shí)間短，因而熱影響區(qū)小。各種壓焊方法的共同特點(diǎn)是在焊接過(guò)程中施加壓力而不加填充材料。壓焊是在加壓條件下，使兩工件在固態(tài)下實(shí)現(xiàn)原子間結(jié)合，又稱固態(tài)焊接。為了提高焊接質(zhì)量，人們研究出了各種保護(hù)方法。在熔焊過(guò)程中，如果大氣與高溫的熔池直接接觸，大氣中的氧就會(huì)氧化金屬和各種合金元素。熔焊時(shí)，熱源將待焊兩工件接口處迅速加熱熔化，形成熔池。s great affinity for oxygen and iron powder are doxycycline titanium rod can be protected in beneficial elements and silicon manganese oxide from into molten pool, cooling after welding quality.Bonding is pressurized conditions, make two workpiece in solid between atoms, realize the bination and solid welding. The pressure welding is used, when the current through the butt weld resistance when the two parts connected by resistance, and rising temperatures, the great when heated to plastic state, in the axial pressure connection bee one.Various pressure welding method is mon in welding process without pressure and filling materials. Most pressure welding methods such as diffusion welding and welding, cold welding are no melting process, thus not so good as welded alloy elements, and the harmful elements into burning weld question, thus simplifying the welding process, welding and improve the safety and hygiene conditions. At the same time as heating temperature, heating time is short of low penetration, heat affected zone. Many difficult welding materials with melting, often can use bonding welded with the base amount of quality connectors.Brazing is the low melting point of use than workpiece materials metal brazing alloy, the workpiece and metallurgical heated to higher brazing alloy melting temperature of melting, workpiece, using the liquid filling analyzed wet parts, and with workpiece interface between atomic interdiffusions of realization, thus realize welding method.Welding the formation of connecting the two are connected the weld seams called. When the welding seam by both in welding heat, and organization and performance variation, a region called the heat affected zone. When the welding workpiece materials for welding materials, welding current and welding in different welding and heat affected zone may cause overheating, improver, hardening or softening phenomenon, also make the welding performance deterioration, and weldability. It will need to adjust welding conditions, a former butt weld at preheating, welding and welding heat preservation can improve the welding quality of welding.In addition, welding is a local rapid heating and cooling process, welding workpiece due to the area around the body cannot free at expansion and contraction, after cooling occurs in the welding of welding stress and deformation. Important after welding products are necessary to eliminate the welding stress, deformation correction.Modern welding technology has a defect of internal and external welding is equal to or above, mechanical properties of welding is connected. In the space by welding welding joints, each place called the strength in doublequick weld quality, but also its geometric shapes, sizes, stress and working conditions. The basic form of joint have docking, lap, tshaped meet (are) and Angle handover etc.Butt weld joints of crosssectional shape, decided to be in before welding welding and thickness of the two forms of groove. Thicker steel welded to weld fully in the place of the open mouth, so slope shape more easily into the electrode wire or. Groove is onesided welding process of form of groove and welding process of both sides. Choose groove, except that the weld fully should also be considered welding process is convenient, the filler metal welding deformation quantity is little, small mouth and low processing cost.The two different thickness steel butt, to avoid to cause serious change sharply section stress concentration, the thick plate cutting edge gradually, to connect the two etc. The static strength and fatigue strength than other joints. In the alternative, shock, or in low pressure vessel in the work, often give priority to the docking joints welded.Lap joints of welding preparation work is simple, convenient, assembly welding deformation and residual stress on site installation, so smaller joints and not important structure often USES. Generally speaking, lap joints is not suitable for alternating load in corrosive medium, such as high and low temperatures under the working conditions.Using a tee and Angle joint structure is usually due to the need. Tee on the welding seam characteristics and the Angle of lap joint Angle of weld similar. When the vertical direction with external welding bee positive fillet weld seam, different surface shape can cause stress concentration, Welding the weld stress condition and joint Angle joint similar.Angle joint bearing capacity is low, generally not used alone, only in