16mn钢板焊接（16Mn steel plate welding）.docVIP

16mn钢板焊接（16Mn steel plate welding） A material introduction The following table 1. chemical composition of Q345 (%): C Si = P = S = Mn = Al = V Nb Ti The content of 0.2 0.035 0.035 0.015 0.55 1.0-1.6 0.02-0.15 0.015-0.06 0.02-0.2 The mechanical properties of Q345C are listed in the following table (%): The mechanical performance index of elongation (%) test temperature of 0 DEG C tensile strength yield point MPa = MPa Numerical 8 5 J = 34 B = 22 sigma sigma (470-650) s (324-259) The wall thickness is 16-35mm, s = 325Mpa; the wall thickness is 35-50mm, s or 295Mpa. 2. welding characteristics of Q345 steel 2.1 carbon equivalent (Ceq) calculation Ceq=C+Mn/6+Ni/15+Cu/15+Cr/5+Mo/5+V/5 The calculation of Ceq=0.49%, more than 0.45%, visible Q345 steel welding performance is not very good, need to develop strict measures in welding process. Easy to appear in the 2.2 issue of Q345 steel welding 2.2.1 heat affected zone hardened tendency Welding of Q345 steel in the cooling process, the heat affected zone is easy to form the quenching microstructure of martensite, the weld hardness increases, the ductility decreases. The results lead to the occurrence of crack after welding. 2.2.2 cold crack sensitivity The welding crack of Q345 steel is mainly cold crack. Two, welding process Preparation, spot welding, preheating, welding in the mouth, backgouging (carbon arc gouging welding), outside the mouth mouth, welding, inspection / special inspection, heat treatment after welding, nondestructive testing (weld quality grade) Three, the choice of the welding parameters Based on the analysis of weldability of Q345 steel. The measures are as follows: 1. welding material selection Due to the cold crack of Q345 steel tends to be larger, the selection of welding material should be low hydrogen type, taking into account the welded joint and base metal should be strong principle, using E5015 (J507) type electrode. Chemical composition table (%): Mn Si S P Cr element C Mo V Ti 0.071 1.11 0.53 0