In this paper, the high chromium cast iron（HCCI）hardfacing layer is deposited on the surface of D32 low-alloy steel by electroslag surfacing method. Combined with the temperature field measurement of the heat-affected zone（HAZ）during the surfacing process, the microstructure and mechanical properties of the HAZ, composite interface and hardfacing layer are studied. The results show that: the heating and cooling rates are slower during the electroslag surfacing, and the temperature distribution in the low alloy steel substrate during the stabilizing stage is uniform; the maximum temperature gradient in the surfacing direction is 23.1 ℃/mm. The maximum thermal stress in the low-alloy steel substrate is 25.9 MPa,lower than its tensile strength, which effectively avoids the occurrence of cracks; the composite interface is smooth and clear,with an austenite band region, about 50 μm in width; The grains of HAZ have grown, whose microstructure is a mixture of ferrite and pearlite. The microstructure of HCCI hardfacing layer is composed of austenite, carbides and a small amount of martensite. The M 7 C 3 type carbides are small and uniformly distributed in austenite grain boundaries. The bonding strength of the composite interface is 96 MPa; the impact energy （53J） of the composite sample is significantly higher than that of the HCCI hardfacing layer（10.7 J）. During abrasion, the HCCI hardfacing layer undergoes martensitic transformation under a large load, the hardness is improved, and an excellent performance in wear resistance was obtained.

双相不锈钢耐点蚀、耐晶间腐蚀和耐氯化物应力腐蚀性能优良,是优良的海洋用金属材料,但其焊接接头常成为薄弱区而发生腐蚀问题.从材料因素综述了双相不锈钢腐蚀研究的进展.首先,总结了合金元素和热处理对双相不锈钢耐腐蚀性能的影响.合金元素分配及其引起的二次相析出及产生的元素贫化区、铁素体/奥氏体相比例的变化决定双相不锈钢的耐腐蚀性能,固溶处理可消除二次相及其周围的贫Cr区、改善铁素体/奥氏体相比例而提高钢的耐腐蚀性能.其次,分析了双相不锈钢焊接接头的腐蚀特点,综述分析了焊接方法、热输入、保护气体、焊后热处理对焊接接头耐蚀性的影响.钨极氩弧焊(TIG)焊接接头的耐局部腐蚀性能良好,采用合适热输入的多道焊,并控制好层间温度,可提高焊接接头的耐腐蚀性能.固溶处理虽可提高接头的耐腐蚀性能,但目前难以应用于管路等工程构件的焊接接头.最后,简要探讨了目前不锈钢腐蚀研究存在的问题和下一步的研究方向.

设计了一种新型多用途跌落试验机,克服了以往跌落试验机仅仅只能进行包装跌落、只能在低高度跌落和容易造成跌落过程中被试品翻滚的不足.本跌落试验机可以保证任意形状被试品裸机试验的固定,而且最高可支持5m的跌落高度,能避免在跌落过程中被试品翻滚的情况,保证被试品的着地姿态.具有结构简单、响应速度快、高度范围大、试验精度高、重复性好和运行稳定性强等特点.通过对比试验,验证了该跌落机在特定试验样品的试验中,对比手持跌落方法更优越.

In order to achieve sea target target simulation,digital echo storage and coherent transfer technology are used to construct a target echo simulator,complete the seeker’s signal reception,fre-quency conversion,and processing to generate multiple different delays,different doppler frequencies and phases.The target echo signals were combined and output,and a prototype was made to verify the sea test.The research results show that the device can simulate point targets and targets,solve broad-band and multi-system compatibility problems,and have flexible parameter settings and convenient op-eration and use.