铸钢和高合金铸钢焊接.pdf

STEEL CASTINGS HANDBOOK Supplement 7 Welding of High Alloy Castings Steel Founders Society of America 2004 Welding of high alloy steel castings by E. A. Schoefer Consultant Steel Founders’ Society of America Edited by M. Blair Steel Founders’ Society of America 1. Introduction Iron-base and nickel-base high alloys - by definition those containing eight percent or more of another element - are widely used for construction of industrial process equipment that must resist the deteriorating effect of a corrosive of high temperature environment. Both wrought and cast forms of such alloys may be welded during the manufacture of finished components so the weldability of the alloys often is a matter of concern to the user. The same welding processes are applied to wrought and cast products and, in general, similar techniques and practices are employed. Differences between wrought and cast alloys in chemical composition and microstructure, however, influence the welding characteristics of each form and must be given consideration. In addition, the high alloys differ markedly from carbon and low alloy steels in physical properties such as electrical resistance, thermal expansion and thermal conductivity. It is essential, therefore, to employ procedures allowing for all these factors when welding high alloy castings. 1.1 All the casting alloys have equal or better weldability than the corresponding wrought alloys, but there are variations from grade to grade in the ease with which satisfactory welds are obtained. The low-carbon, austenitic grades usually are considered easier to weld than high-carbon austenitic or straight-chromium ferritic or ma