.2.25 Of Cr-1mo Steel Tig Surfacing Fe <sub> 3 </ Sub> Al Intermetallic Compounds

In this paper, a rational technological process of Fe~AL intermatallics deposited on 2. 25Cr條Mo steel surface by TIC is determined, on the basis of which, the microstructures and fracture appearances of weld overlays are observed and analyzed in detail by means of optical microscope (OLM),X梤ay diffraction instrument and scanning electronic microscope(SEM). Furthermore, through the hardness test for weld overlay and hend test, effect of Al content in weld overlay on mechanics performances, especially ductility is investigated. At last, some significant results are obtained and have an important guiding significance for the application of Fe1Al intermetallics in production and service of boiler steam pipes in high梩emperature condition. The results are as follows: 1. In condition of dilution no more than 20%, the heat input of 8. 3k.J/cm or so is suggested. When using filler metal with 39. 4~52. Oat.%Al contents and a preheat of 200C and postweld heat of 700C for one hour, the weld overlays with 2l.63?9.O3at.% Al contents which can he free of cracks, will he obtained. 2. Measured restil ts show that the hardness of Fe桝] alloy weld overlay is higher than that of the 2.25Cr條Mo matrix and rises with the increase of Al content. Moreover, embrittlement of weld overlay also rises with the increase of content. 3. The macro梖eature of Fe.1A1 weld overlay fracture is brittle and the micro梖eature of that is cleavage. With the increase of?Al content, the mixture frcture feature of cleavage and intercrystalline appears in weld overlay.