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我国内燃机气阀钢系列化发展趋势 总被引:9,自引:1,他引:8
根据我国汽车工业的发展形势预测气阀钢的发展趋势,并阐述气阀钢系列化的重要性,描述了世界各国气阀钢的系列概况,探讨了我国气阀钢系列化发展趋势,包括马氏体气阀钢、奥氏体气阀钢、气阀合金、低俣金进气阀用钢4部分。重点是马氏体和氏体气阀钢的发展。 相似文献
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结合某特钢厂R8 m二机二流不锈钢方坯连铸机的设备情况,介绍马氏体不锈钢气阀钢和奥氏体不锈钢气阀钢的设计特点、凝固组织和凝固特点。 相似文献
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为了研究42CrMoS4棒材淬火劈裂的原因,采用扫描电镜、金相显微镜和电子探针对试样组织形貌及成分进行了分析。结果表明:该棒材劈裂始于芯部,与芯部马氏体异常组织和聚集的硫化锰有关,而芯部马氏体的形成与带状偏析有关,其中Cr、Mo元素成分偏析严重。芯部马氏体与珠光体和铁素体共存,在应力条件下导致马氏体区开裂,而聚集的硫化锰又加速了裂纹扩展,造成整个棒材劈裂。 相似文献
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Cr12钢是一种含铬11~12%的廉价无奥氏体不锈钢。该钢具有铁素体一马氏体双相组织,通过添加微量合金元素,具有良好的焊接性、韧性以及耐蚀和耐磨性能,其截面厚度达30 mm的型材焊接后仍具有很好的韧性。这种钢材的商品形状有:中厚板、薄板、带卷材以及棒材和型材,可取代电镀锌钢 相似文献
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B7钢Φ22 mm热轧盘条在冷拔中断裂,采用断口观察、化学成分、显微组织检验以及能谱分析测试了断裂盘条。测试结果表明:Mn、Cr偏析导致盘条中心存在马氏体组织是造成拉拔断裂的原因。通过轧制吐丝温度由905~915℃降至840~850℃以及保温时间由285 s延长至420s,可有效减少心部马氏体的产生,消除了冷拔断裂现象。 相似文献
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欧光清 《金属材料与冶金工程》2011,39(5):10-14
在盘卷产品酸洗去除氧化皮后,表面发现多条短小裂纹缺陷,分析发现其来源于连铸坯表面,这种短小裂纹是冷镦钢致命的弱点,生产紧固件产品时容易引起冷镦开裂。在炼钢初期由于缺陷深度较深,较隐蔽,需要对连铸方坯表面进行全面扒皮修磨,以磨净缺陷为主。生产试验中,对修磨与未修磨的铸坯进行了对比轧制,以及对修磨后的轧制坯与连铸小方坯进行了对比轧制,发现大压下量轧制坯修磨工艺轧成的盘卷产品可以消除表面短小裂纹缺陷。 相似文献
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通过光学金相及扫描电镜等分析手段,对45钢油缸活塞杆在矫直过程中发生断裂的原因进行了分析。结果表明,断裂主要原因是中频回火时回火不充分,圆钢的表面淬硬层形成了硬且脆的回火马氏体组织。 相似文献
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A thermal model for the grinding of quenched alloy roll steels has been developed. The temperatures in the cutting area are calculated by this model, and the effect of grinding conditions on the structure and hardness of the surface layers of a roll steel quenched for martensite is studied. 相似文献
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Seok Su Sohn Byeong-Joo Lee Sunghak Lee Jai-Hyun Kwak 《Metallurgical and Materials Transactions A》2014,45(12):5469-5485
In the present study, effects of Mn addition on cracking phenomenon occurring during cold rolling of ferritic light-weight steels were clarified in relation to microstructural modification involving κ-carbide, austenite, and martensite. Four steels were fabricated by varying Mn contents of 3 to 12 wt pct, and edge areas of steel sheets containing 6 to 9 wt pct Mn were cracked during the cold rolling. The steels were basically composed of ferrite and austenite in a band shape, but a considerable amount of κ-carbide or martensite existed in the steels containing 3 to 6 wt pct Mn. Microstructural observation of the deformed region of fractured tensile specimens revealed that cracks which were initiated at ferrite/martensite interfacial κ-carbides readily propagated along ferrite/martensite interfaces or into martensite areas in the steel containing 6 wt pct Mn, thereby leading to the center or edge cracking during the cold rolling. In the steel containing 9 wt pct Mn, edge cracks were found in the final stage of cold rolling because of the formation of martensite by the strain-induced austenite to martensite transformation, whereas they were hardly formed in the steel containing 12 wt pct Mn. To prevent or minimize the cracking, it was recommended that the formation of martensite during the cooling from the hot rolling temperature or during the cold rolling should be suppressed, which could be achieved by the enhancement of thermal or mechanical stability of austenite with decreasing austenite grain size or increasing contents of austenite stabilizers. 相似文献
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主要研究了过时效温度和时间对冷轧低碳双相钢显微组织和磁性能的影响。结果表明,过时效温度对双相钢的显微组织和磁性能影响较大。随着过时效温度的升高,马氏体体积分数稍有降低,马氏体逐渐发生分解。透射电镜结果表明,当过时效温度达到380℃时,板条马氏体边界已变得模糊,同时观测到碳化物的析出。双相钢的磁性能对过时效温度非常敏感。矫顽力和磁滞损耗随过时效温度的升高逐渐降低,而最大磁导率、剩磁和10000A/m磁场下的磁感应强度则呈升高趋势。过时效时间对双相钢显微组织和磁性能有较弱的类似影响。 相似文献