30CrMnsi联接环断裂失效分析

对断裂的联接环进行了化学成分、机械性能、显微组织核验，指出回火工艺不当、锻造缺陷以及原材料化学成分不合格，是造成断裂事故的主要原因．在此基础上．提出了改进措施．     

As,Sb,Sn对30CrMnSiA钢力学性能的影响

在３０ＣｒＭｎＳｉＡ钢中加入不同量的Ａｓ，Ｓｂ，Ｓｎ元素，研究了这些元素单独存在及复合存在时对钢的强度，塑性，冲击韧度及韧脆转变温度的影响规律，并用扫描电镜及俄歇能谱分析了Ａｓ，Ｓｂ，Ｓｎ导致晶界脆化的机理。     

Strain-rate dependence of low cycle fatigue behavior in a simulated BWR environment

The strain-rate dependence of low cycle fatigue behavior of ASTM A533B low-alloy steel was investigated in a simulated BWR environment. Fatigue resistance of the steel was found to be closely dependent on cyclic strain rate in high-temperature water. A tortuous cracking morphology was dominant at high strain rate and typical fan-like or quasi-cleavage cracking patterns were frequently observed on the corresponding fracture surface. An entirely straight cracking morphology, however, became dominant at low strain rate. Evidence of crack arrest was found on the fracture surface rather than fan-like or quasi-cleavage cracking patterns. The above cracking behavior in simulated BWR water may be attributed to a strain-rate-induced change in the dominant environmentally assisted cracking (EAC) mechanism from hydrogen-induced cracking to film-rupture/slip-dissolution-controlled cracking.     

EFFECT OF AGING ON HYDROGEN EMBRITTLEMENT SUSCEPTIBILITY OF STEEL Cr21Ni6Mn9N

Effects of 650℃ aging for 1—1000 h on structure and hydrogen embrittlement susceptibility(HES)of steel Cr21Ni6Mn9N have been investigated.The results show that M_(23)C_6 typecarbide precipitates at grain boundaries and Cr-depletive region appears beside them duringaging.The precipitates grow and connect each other as the aging time prolongs.Meanwhile,the degree of Cr-depletion aggravates first and then recovers gradually while the aging time isvery long,i.e.,1000 h.The HES of the steel increases with increasing aging time but does notreduce with the recovery of Cr content at the Cr-depletive region.That implies that the ex-isting of carbides at grain boundaries might be the main reason which promotes the HES ofsteel during aging.     

金属陶瓷防腐蚀涂层替代镀镉或镉−钛工艺的研究

针对钢制零件采用镀镉、镀镉?钛工艺存在氢脆、镉脆风险及不利于环境保护的现状,研究采用涂覆IPcote9183或IPcote9183+IPseal9184形成金属陶瓷防腐蚀涂层(MCAC)的替代工艺。对比结果表明:上述2种金属陶瓷涂层的氢脆性和耐蚀性优于镉及镉?钛镀层,其他性能相当,能够完全替代它们应用于起落架钢制零件的表面防护。     

Sintered stainless steels: Fatigue crack propagation resistance under hydrogen charging conditions

Monophasic and multiphasic (two and three phases) sintered stainless steels were prepared both considering premixes of AISI 316LHC and AISI 434LHC stainless steels powders and using a prealloyed duplex stainless steel 25% Cr, 5% Ni, 2% Mo powder. Their fatigue crack propagation resistance was investigated both in air and under hydrogen charging conditions (0.5 M H₂SO₄ + 0.01 M KSCN aqueous solution; applied potential = −700 mV/SCE), considering three different stress ratios (R = 0.1; 0.5; 0.75). Fatigue crack propagation micromechanisms were investigated by means of fracture surface scanning electron microscope (SEM) analysis.For all the investigated sintered stainless, fatigue crack propagation resistance is influenced by hydrogen charging and an increase of crack growth rates dependent on the steel microstructure is obtained. Experimental results also allow to identify the sintered stainless steel obtained from the prealloyed 25% Cr, 5% Ni, 2% Mo powder as the most resistant to fatigue crack propagation in air and under hydrogen charging conditions.     

Hydrogen embrittlement of high strength steel electroplated with zinc-cobalt alloys

Slow strain rate tests were performed on quenched and tempered AISI 4340 steel to measure the extent of hydrogen embrittlement caused by electroplating with zinc-cobalt alloys. The effects of bath composition and pH were studied and compared with results for electrodeposited cadmium and zinc-10%nickel. It was found that zinc-1%cobalt alloy coatings caused serious hydrogen embrittlement (EI 0.63); almost as severe as that of cadmium (EI 0.78). Baking cadmium plated steel for 24 h at 200 °C gave full recovery of mechanical properties but specimens plated with zinc-1%cobalt and then baked still failed in 89% of the time of unplated controls. It was shown that hydrogen uptake and embrittlement could be controlled by depositing thin layers of cobalt or nickel at the steel/coating interface. For example, the least embrittlement was caused by zinc-10%nickel (EI 0.037) due to a nickel rich layer with very low hydrogen diffusion coefficient that formed during the initial stages of electroplating. Similarly, a 0.5 μm nickel layer was effective in lowering the embrittlement caused by zinc-1%cobalt to that of zinc-10%nickel. Furthermore, a 0.5 μm cobalt layer deposited before a zinc-1%cobalt coating gave virtually 100% recovery of mechanical properties after baking.     

7175铝合金锻件毛坯高温均匀化处理工艺研究

对7175铝合金大型锻件生产过程中的关键工艺－－高温均匀化处理进行了研究；分析了锻造毛坯经过高温处理和未经高温处理的锻件的组织、性能差别及其机理。     

乏燃料运输罐体旋转凹槽开裂原因分析

某乏燃料运输容器壳体的旋转凹槽在制造过程中发生开裂,为了确定失效原因,防止此类失效事件再次发生,实验对该旋转凹槽的化学成分、力学性能、金相组织和断口形貌进行了分析,确定了断裂原因。结果表明,旋转凹槽的失效模式为氢致延迟开裂,材料中H含量偏高和材料脆化是导致旋转凹槽发生氢致开裂的主要原因。     

STUDY OF MECHANISM OF RQ EMBRITTLEMENT OF Fe_(73.5)Cu_1-Nb_3Si_(13.5)B_9 NANOCRYSTALLINE SOFT MAGNETIC ALLOY

Rapidly quenching embrittlement (RQE) sometimes appears in Fe73.5Cu1Nb3Si13.5B9 nanocrystalline soft magnetic alloy (FINEMET) during production process. As a re-sult of RQE the ductility of the as-quenched ribbon drops seriously. The mechanism of RQE has been elucidated in the recent works of current authors. It was believed that RQE is due to the structural relaxation but not related to a-Fe(Si) crystallization. In this paper, the high resolution TEM (HRTEM) method and image digital processing were applied to analyze the HRTEM images of two FINEMET rapidly quenched ribbons with different thicknesses in detail. In the thinner ductile sample, the ordering domains with the size of about 3nm are observed. In the thicker RQE sample, the metastable nanocrystalline domains with the size of 18nm are observed along with the structural relaxation. These domains seem to have Fe3B-like metastable phase struc-ture on nanometer scale. The result indicates that the local atomic ordering regions extend when RQE induced