共查询到20条相似文献,搜索用时 15 毫秒
1.
《Baosteel Technical Research》2010,(Z1):78
Traditionally,austenitic stainless steels 304 and 316 have been employed in coastal regions as roofing materials unfortunately,they are expensive and not fully resistant to pitting corrosion under severe coastal corrosive environment.A ferritic stainless steel B445R was developed.Compared with austenitic 316L,B445R is①less costly;②uperior corrosion resistant with minor maintenance for long-term service;③insusceptible to thermal distortion in the welding seam. B445R sheet shows a higher yield strength and lower tensile strength,lower elongation and lower work-hardening than austenitic 316L.It can be easily fabricated and deformed just like plain carbon steel.After bending 180o,there is no occurrence of "cracking" or noticeable "orange peel".The formability of the welding seam is also satisfactory.The pitting potential of B445R is 650 mV,larger than that of 304 and 316L,as shown in Fig.1. The corrosion rate of B445R submerged in 6%FeCl,solution is 0.3 -0.56 g/(m2 ? h-1),much lower than that of 316L,as shown in Fig.2.The superior pitting corrosion resistance of B445R can be ascribed to synergetic effect of higher Cr and Mo. Dull-finished B445R sheets have been employed as the roofing materials for Guangzhou Asian Games Arena,as shown in Fig.3.About 380 t of 1.0 mm B445R with dull finish was used for roofing panels.About 100 t of 0.8 mm B445R with hairline or fluororesin paint finish was used for side wall panels.The composite roof build-up (from up to bottom) includes:①shingles of ferritic stainless steel B445R;②Kalzip-type standing seam of austenitic 304;③water-proof DFM;④structural steel;⑤75 mm thick insulation;⑥secondary purlin of 150 mm×100 mm×4.5 mm of galvanizied Q235;⑦0.8 mm thick profile deck of galvanizied Q235;⑧acoustic insulation.The roofing shingles or panels with the same width but different length were formed by bending four sides and fixed to a "L" shape reinforcing frames of stainless steel by fasteners.The "L" frames was connected to ribs of the standing seam by a clamping fixture made of aluminum. 相似文献
2.
3.
《粉末冶金学》2013,56(4):290-293
AbstractDuplex stainless steels prepared from mixes of elemental powders with martensitic 410L steel have been shown to possess stable dual phase microstructures. Following heat treatment, the steels possess good mechanical properties. The addition of boron as a sintering aid reduces compressibility but promotes densification through transient liquid phase sintering; its effect on corrosion resistance is particularly favourable. 相似文献
4.
Eleven alloys similar to commercial A-286 but with small variations in chemistry were tested to assess whether the performance of this type of stainless steel, which shows a ductility (RA) loss of about 48 pct when hydrogen charged, could be improved. It was found that removal of Mn resulted in anRA loss of only 15 pct; low Mn plus a 5 pct increase in Ni gave further improvement to 11 pctRA loss. Reductions in C, Si and B had little effect on theseRA losses. None of the above changes had significant effect on strength. Other chemistry changes were unsuccessful: additions of Al, Ti, Ti + Mo, or decreases in Ni, increased the ductility loss. Extensive examination of thin foils permitted a structural rationale for behavior in hydrogen in terms of the effects of second-phase particles on ductile fracture, particularly as affected by the misfit between the austenite and the γ’ precipitates. This rationale was consistent with fractographic observations. 相似文献
5.
Eleven alloys similar to commercial A-286 but with small variations in chemistry were tested to assess whether the performance
of this type of stainless steel, which shows a ductility (RA) loss of about 48 pct when hydrogen charged, could be improved. It was found that removal of Mn resulted in anRA loss of only 15 pct; low Mn plus a 5 pct increase in Ni gave further improvement to 11 pctRA loss. Reductions in C, Si and B had little effect on theseRA losses. None of the above changes had significant effect on strength. Other chemistry changes were unsuccessful: additions
of Al, Ti, Ti + Mo, or decreases in Ni, increased the ductility loss. Extensive examination of thin foils permitted a structural
rationale for behavior in hydrogen in terms of the effects of second-phase particles on ductile fracture, particularly as
affected by the misfit between the austenite and the γ’ precipitates. This rationale was consistent with fractographic observations. 相似文献
6.
《Baosteel Technical Research》2010,(Z1):94
High-strength steels have been attracting more and more attention of people,Unfortunately.deterioration of ductility limited their applications.To solve this problem,a nano-structured stainless steel sheet is developed to combine high strength and high ductility.Processing of the surface mechanical attrition treatment(SMAT) was introduced to obtain a nano-grain layer on the double surface of the stainless steel sheet.The microstructure of the nanostructured steel sheet is characterized by an alternate distribution of coarse grained layer and nanocrystalline layer.Then the dual surface nano-crystallized stainless steel sheets were co-warm rolled at 500℃.The experimental results reveal that the mechanical properties of the nanostructured steel exhibit high yield strength in the range of 700 -950 MPa and tensi le strength higher than 930 MPa.Moreover,elongation to fracture reaches to 15%-48%, together with a uniform elongation stabilized to 13%-45%. 相似文献
7.
8.
9.
10.
11.
不锈钢AOD渣在冷却过程中由于晶格转变体积膨胀导致粉化,易造成粉尘污染。研究表明,出渣时喷入含硼改质剂能有效抑制AOD渣从β-C2S相向γ-C2S相的晶格转变,从而使粉化扬尘率降低90.1%。对无害化处理后的不锈钢AOD渣进行资源化利用探讨,结果显示,由于钢渣具有水硬胶凝活性,可作为水泥砂浆掺合料取代部分水泥,掺量范围应在0~30%之间。同时,对AOD渣及其水泥试块进行毒性浸出检测,结果表明,其中总铬、六价铬等浸出值均低于标准限值,不存在重金属浸出的问题,可进行后续资源化利用。 相似文献
12.
An alloy development program has been undertaken with the aim of identifying an Fe-Cr-Mn stainless steel with ferritic-martensitic
microduplex phase balance of sufficient stability to produce moderate strength and ductility, good impact resistance and acceptable
as-welded properties. A microduplex, low C and N, Ti stabilized composition of Fe-11.5 pct Cr-3 pct Mn has been found to provide
a yield strength of ⋍550 MPa, a tensile strength of ≃650 MPa, tensile elongation of 20 pct, a CVN impact transition temperature
of-115°C (at 0.33 cm gage) and good weldability as determined by bend, impact, and intergranular corrosion testing. The alloy
possesses general corrosion resistance roughly comparable to T405 and T430 ferritic stainless steels. The impact resistance
achieved with the mixture of ferrite and martensite is inconsistent with previous concepts of second phase toughening in microduplex
alloys, with the mixture apparently being significantly tougher than either of its components in bulk form.
J.R. WOOD formerly with Allegheny Ludlum Steel Corporation, Brackenridge, PA 相似文献
13.
讨论了B2101、B2304、B2205以及B2507双相不锈钢的焊接性.针对双相不锈钢的焊接实践推荐了合理的焊接方法、填充金属、热循环及焊接保护气体参数,并列出了双相不锈钢在不同焊接方法条件下的典型接头性能;针对特殊焊接方法推荐了合适的焊后热处理工艺.结果表明,双相不锈钢同常规奥氏体不锈钢一样具有较好的焊接性,但焊接过程须避免过大或过小的热输入以免造成接头腐蚀性能的下降;焊接保护气中添加一定含量的氮较纯氩气保护可以使接头获得更高耐蚀性能,同时适当温度范围内的短时热处理也可以明显改善接头耐点腐蚀性能.实践表明,通过合适的焊接方法和焊接工艺控制,可以获得具有优异综合性能的双相不锈钢焊接接头. 相似文献
14.
The mechanical properties and microstructures of commercial 11 to 29 pct Cr ferritic steels were examined as functions of
aging times to 1000 h at 371, 482, and 593°C. Of the properties evaluated, changes in impact transition temperatures were
the best measure of embrittlement. Embrittlement at 482°C occurs most rapidly in the 29 pct Cr alloy and somewhat more slowly
in the stabilized 26 pct Cr alloy. The stabilized 18 pct Cr alloy embrittles much more slowly while little, if any, embrittlement
was detected in a stabilizedll pct Cr alloy. Embrittlement at 482°C was characterized by a rapid change in properties followed
by a plateau region and then further property changes. The early property change is attributed to precipitation of interstitial
compounds and the later change to classic 475°C embrittlement. The onset of 475°C embrittlement in the two highest Cr alloys
was accompanied by clustering of Cr atoms along {100} planes indicative of spinodal decomposition. Concurrent with clustering
there was also a change from turbulent slip to a more planar slip along {110} planes. Some embrittlement was observed after
longer exposures at 371°C which was attributed to a combination of 475°C embrittlement and the precipitation of interstitial
compounds. Two of the alloys also embrittled at 593°C, accompanied by optically observable precipitates. The precipitate in
the stabilized 18 pct Cr alloy was identified as Laves (Fe2Ti) phase. One of the precipitates in the 29 pct Cr alloy was identified as sigma phase.
Formerly with Allegheny Ludlum Steel Corporation. 相似文献
15.
Ann M. Ritter Michael F. Henry Warren F. Savage 《Metallurgical and Materials Transactions A》1984,15(7):1339-1351
Nitronic 50 and Nitronic 50W, two nitrogen-strengthened stainless steels, were heat treated over a wide range of temperatures,
and the compositions of the ferrite and austenite at each temperature were measured with analytical electron microscopy techniques.
The compositional data were used to generate the (γ + δ phase field on a 58 pct Fe vertical section. Volume fractions of
ferrite and austenite were calculated from phase chemistries and compared with volume fractions determined from optical micrographs.
Weld solidification modes were predicted by reference to the Cr and Ni contents of each alloy, and the results were compared
with predictions based on the ratios of calculated Cr and Ni equivalents for the alloys. Nitronic 50, which contained ferrite
and austenite at the solidus temperature of 1370 °C, solidified through the eutectic triangle, and the weld microstructure
was similar to that of austenitic-ferritic solidification. Nitronic 50W was totally ferritic at 1340 °C and solidified as
primary delta ferrite. During heat treatments, Nitronic 50 and Nitronic 50W precipitated secondary phases, notably Z-phase
(NbCrN), sigma phase, and stringered phases rich in Mn and Cr. 相似文献
16.
R. F. Hehemann 《Metallurgical and Materials Transactions A》1985,16(11):1909-1923
The similarities and differences in the stress corrosion cracking response of ferritic and austenitic stainless steels in
chloride solutions will be examined. Both classes of materials exhibit a cracking potential: similar transient response (to
loading) of the potential in open circuit tests or the current in potentiostatic tests and similar enrichment of chromium
and depletion of iron in the film associated with localized corrosion processes. The ferritic steels are more resistant to
localized corrosion than are the austenitic steels, which is responsible for the difference in the influence of prior thermal
and mechanical history on cracking susceptibility of the two types of steel. Similarities in the fractography of stress corrosion
cracks and those produced by brittle delayed failure during cathodic charging of the ferritic steels indicate that hydrogen
embrittlement is involved in the failure process. 相似文献
17.
18.
John Wareing 《Metallurgical and Materials Transactions A》1977,8(5):711-721
Low cycle fatigue failures occur by the initiation and controlled growth of a surface crack. The development of crack propagation
models, based on continuum mechanics, have enabled successful predictions of fatigue life at both room and elevated temperatures.
This paper attempts to extend such models to cover the situations in which creep damage, introduced during periods of stress
relaxation, influences the rate of growth of the surface fatigue crack. Equations predicting fatigue life as a function of
hold period are in good agreement with experimental data, for Type 304 stainless steel, Type 316 stainless steel and Incoloy-800. 相似文献
19.
20.
Raghavan Ayer C. F. Klein C. N. Marzinsky 《Metallurgical and Materials Transactions A》1992,23(9):2455-2467
The effect of aging on the precipitation of grain boundary phases in three austenitic stainless steels (AISI 347, 347AP, and
an experimental steel stabilized with hafnium) was investigated. Aging was performed both on bulk steels as well as on samples
which were subjected to a thermal treatment to simulate the coarse grain region of the heat affected zone (HAZ) during welding.
Aging of the bulk steels at 866 K for 8000 hours resulted in the precipitation of Cr23C6 carbides, σ, and Fe2Nb phases; the propensity for precipitation was least for the hafnium-stabilized steel. Weld simulation of the HAZ resulted
in dissolution of the phases present in the as-received 347 and 347AP steels, leading to grain coarsening. Subsequent aging
caused extensive grain boundary Cr23C6 carbides and inhomogeneous matrix precipitation. In addition, steel 347AP formed a precipitate free zone (PFZ) along the
grain boundaries. The steel containing hafnium showed the best microstructural stability to aging and welding.
Formerly with Exxon Research and Engineering Company. 相似文献