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The Welding of Aluminum & Its Alloys Part 6

Tham khảo tài liệu 'the welding of aluminum & its alloys part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Table 5.1b Fatigue life prediction for welded items from BS 8118 96 The welding of aluminium and its alloys cannot be done then thickening the component will reduce the stress experienced by the weld. The fatigue life of the weld can be improved by inducing compressive stresses at the toe of the weld. Overstressing the joint or hammer peening the weld toe will both do this although great care needs to be taken that an over-enthusiastic application of either technique does not introduce defects. Dressing of the weld toes has been found to be an effective method but once again over-enthusiastic grinding can reduce rather than improve fatigue life. If the weld toes are ground this should be carried out by fully trained personnel. Grinding should be performed transverse to the weld toes in order that the grinding marks are parallel with the principal stress. 6 TIG welding 6.1 Introduction Tungsten arc inert gas shielded welding EN process number 144 abbreviated to TIG TAGS or GTAW USA is an arc welding process that uses a non-consumable tungsten electrode and an inert gas shield to protect the electrode arc column and weld pool as illustrated in Fig. 6.1. The welding arc acts as a heat source only and the welding engineer has the choice of whether or not to add a filler wire. The weld pool is easily controlled such that unbacked root passes can be made the arc is stable at very low welding currents enabling thin components to be welded and the process produces very good quality weld metal although highly skilled welders are required for the best results. It has a lower travel speed and lower filler metal deposition rate than MIG welding making it less cost effective in some situations. TIG tends to be limited to the thinner gauges of aluminium up to perhaps 6 mm in thickness. It has a shallower penetration into the parent metal than MIG and difficulty is sometimes encountered penetrating into corners and into the root of fillet welds. Recommended weld preparations .