Methods To Avoid The Appearance Of Cold Cracks During Welding Metal June 2, 2014 at 6:40 am
The method of IMET-4 to evaluate resistance against the formation of cold cracks alloys after treatment at various temperatures and strain, for example, after quenching, the thermal cycle of welding (for HAZ) thermomechanical processing, etc. Processing is performed in a special car IMET-4: flat samples of the base metal was adjusted to the desired temperature by programmed heating current in the cooling process load in the required temperature range and then kept at a constant tensile load to failure. Sample CMEA-19HT (GOST 26388-84) – welding set of three flat rectangular composite samples with thickness of 12 40 mm varying the total length of welded elements 100, 150 and 300 mm, rigidly fixed at both ends. To fix the samples to them pre-welded to a special limit switches. Before welding, the samples installed in the clamping device, which is a massive plate with slots, in which the clamping bolt is fixed limit switches. Perform single-pass welding test joints.
Weld together all three samples. After welding test kept in the allocated position for 20 h. After release from adaptation in the samples reveal the cold cracks of different control methods. oa quantitative measure propensity to cold cracking take the maximum length of welded elements where cracks. Indicator is the result of welding two identical three samples.
Sample "Tekki" (GOST 26388-84). Flat rectangular sample thickness of 5 = 12 40 mm is longitudinal slit in the center, issued in the form of a U-shaped cuts. Sample welded in a free state and allowed to stand 20 hours after welding Welding tests are performed manually coated electrodes, submerged arc or gas shielded. Cracks formed in the root of the weld. Mandatory condition test – the presence of lack of fusion in the weld root, which serves as a stress concentrator. Cracks identify the different control methods, including etching acid solution followed by a break of the sample. As a quantitative indicator of resistance to fracture can be a percentage of the total length of cracks in the length of the seam or area of cracks to cross-sectional area seam. Quantitative indicator can also be heating temperature at which no longer cracks.