消除奥贝球铁中锰的偏析和不利影响的研究

研究了消除奥贝球铁中锰的偏析及其不良影响的工艺措施。对含Mn0．8%左右的奥贝球铁,通过强化孕育处理,调整硅量或奥氏体化温度,以及等温淬火后进行回火处理,均可消除锰含量增高对组织和性能的不利影响。在此基础上,可扩大生铁含锰量允许范围、或利用锰提高淬透性,从而促进奥贝球铁的推广应用。     

Mn含量对0.15C-0.6Si-Mn TRIP钢组织和力学性能的影响

经过在两相区退火和贝氏体区等温处理，研究了两种不同锰含量的低硅TRIP钢的组织和力学性能，试验结果表明，低硅和低锰钢的残留奥氏体量少，力学性能差；增加锰含量，能提高残留奥氏体量及拉伸强度和伸长率，其力学性能与常规低碳Si-MnTRIP钢的水平相关，用电子探针测试了两相区退火钢中锰和硅的分布情况，发现锰在临界区退火时不发生再分配。     

锰硼抗磨白口铸铁组织及性能的试验研究

通过试验研究了锰硼抗磨白口铸铁的碳化物结构类型（M3C型）和锰含量及奥氏体化温度对其组织中残余奥氏体量的影响，试验结果表明：锰含量和奥氏体化温度提高，残余奥氏体量增加，材料硬度降低，冲击韧度提高。     

高碳硅锰铸钢中夹杂物的形成与控制

对高碳硅锰铸钢中夹杂物的主要类型进行了详细研究,发现高碳硅锰铸钢中除了常见的硫化物夹杂外,还存在含硅夹杂物、含铝夹杂物、含钙夹杂物和稀土夹杂物等。采用钢液高温出炉、吹氩处理以及吹氩后静置处理等工艺措施,可以明显减少高碳硅锰铸钢中的夹杂物,夹杂物含量可以控制在0.1%以下。高碳硅锰铸钢经吹氩去夹杂物处理后,韧性明显改善,尤其是冲击韧性提高21.2%,达到16.6J/cm2。     

覆膜砂离心铸造球墨铸铁管性能的研究

论述了以覆膜砂离心铸造和用含锰及微量元素含量较高的再生铁进行球化处理浇注球铁管的方法，研究了模内孕育，随流孕育和金属铋孕育对铸态球铁管塑性的影响，考察了锰，硅和碳当量及衬砂层厚度对铸态球铁管塑性的影响规律。     

碳锰含量对低碳(锰)钢过冷奥氏体形变过程转变动力学的影响

提高低碳(锰)钢中碳含量，低碳(锰)钢形变强化相变孕育期明显延长，转变动力学曲线整体向高应变方向移动．提高锰含量，相变孕育期有所延长，转变动力学过程明显变缓．提高碳、锰含量，钢中铁素体形核率增大，晶粒细小，碳的影响程度比锰显著．过冷奥氏体形变过程铁素体转变分三个阶段，第一阶段符合Cahn的“位置饱和”机制，第二、三阶段不符合“位置饱和”机制。     

部分元素对紧固件钢性能的影响

正1.碳(C):随含碳量的增加,强度增加,塑、韧性下降,碳对钢材的冷镦性影响最大,也影响焊接性和热处理性(淬透性、淬硬性、开裂和畸变等)。生产中碳大于0.28%时,冷变形前要进行球化退火处理。2.锰(Mn):提高钢件强度(抗拉、抗弯强度)、提高淬透性(增加淬硬层深度)。锰还能改进表面质量。但锰量过高,对冷塑性变形、延展性和焊接性不利,并会影响电镀时镀层的控制。热处理水淬易开裂。     

碳硅含量对锰系白口铸铁性能的影响

探讨碳硅含量对锰系白口铸铁组织与性能的影响，以扩大锰系白口铸铁的应用范围。     

硅锰稀土元素对铸态锌基合金组织性能的影响

采用正交组合回归设计实验方法，研究硅、锰元素对持态锌基合金力学性能的影响规律。结果表明，硅、锰元素对锌合金的室温硬度、100℃硬度、抗压强度和冲击韧性都有显著影响。适当控制硅、锰含量、并加入稀土元素进行变质处理，可得到具有较高强韧性的耐磨锌合金。     

高强度高塑性TWIP钢的组织和性能

研究了一种高强高塑的汽车用TWIP钢。TWIP钢的锰含量为15％～30％，抗拉强度为600～1100MPa，断后伸长率高达95％。介绍了孪晶诱发相变的微观机理，层错能对TWIP效应的影响以及显微组织对钢的力学性能的影响。锰含量为15％～30％时，钢的塑性得以提高的机理主要是γ→ε→α相变诱发的TRIP效应；随着锰含量增加，孪晶形成逐渐起主导作用。     

非合金奥贝球铁的成分组织和性能研究

本文研究了Ｓｉ、Ｍｎ对非合金奥贝球铁组织和性能的影响,Ｍｎ增加组织中的白亮区,使奥贝球铁的塑性和韧性显著下降,但Ｍｎ可提高淬透性。对含Ｍｎ０．８％非合金奥贝球铁,使适量的Ｓｉ能减少组织中的白亮区,部分抵消Ｍｎ的不利影响。     

Embrittlement of cast Mn–Ni–Al bronzes

Abstract

A review of the literature of Mn–Ni–Al bronze alloys reveals a sensitivity of these alloys to slow cooling conditions, which has a markedly detrimental effect on impact resistance and failure of large cast components. Investigations of the cause of failures as described in this review have not resulted in solutions. This paper presents a metallurgical study of the phenomenon of the embrittlement of the Mn–Ni–Al bronzes. The study is based on investigations on material of an experimental casting containing 18–21 wt-% manganese and on material of failed ship propeller castings with 11–15 wt-% manganese. The investigations revealed the appearance of a hard and brittle phase in the structure of the material depending on cooling conditions and manganese content. This phase can be identified with the Mn(β) type phase in the Fe–Mn– Al alloys. The Mn(β) type phase has a hard and brittle nature and is assumed to be the cause of embrittlement of the Mn–Ni–Al bronzes.     

Corrosion Behaviour of Manganese-Containing. Stainless steels. I. Galvanostatic measurements in H2SO4 solutions

The results of galvanostatic polarization experiments on four 17.3% Cr / 5.3% Ni stainless steels containing increasing amounts of Mn (upto 13.9%) are compared with those of an 18/8 stainless steel. All alloyes exhibit an initial step for the dissolution of Fe. A second arrest is recorded in dilute acid solutions and/or when applying high currents, and is related to the oxidation of the Cr. With an alloy containing traces of N₂, a third arrest is observed in dilute acid solutions; it is attributed to the oxidation of Cr₂N. The incorporation of Mn in CrNi steels is detrimental to their anti-corrosion characteristics. The content of this metal should be kept as low as feasible.     

Effect of Trace Additions (Be,Cr, Mn and Co) on the Mechanical Properties and Fracture Toughness of Fe-containing Al-7Si-0.3Mg Alloy

Abstract

The detrimental effect of iron impurity on the mechanical properties and fracture toughness of Al-7Si-0.3Mg alloy has been widely reported. It is also quite evident that Fe forms the intermetallic compound β-FeSiAl₅, which exists as needles/plates in the interdendritic regions, thereby lowering the mechanical properties. However, very little is known about the methods of counteracting this detrimental effect. The present study has shown that trace additions of Be, Cr, Mn and Co, individually or combined, tie up the iron to form new phases with altered morphology which significantly influence the mechanical properties. Among the trace additions, Be is found to be most effective in neutralising the detrimental effect of Fe on tensile properties. Hardness, tensile and yield strengths, ductility, dynamic fracture toughness (K_d and, K_jd remain constant with an increase in Fe from 0.1 to 0.93% where Be additions are present. Be additions in combination with Mn and/or Cr are also found to nullify the detrimental effect of Fe. However, Be and Mn, when added together, seem to be most effective in providing better tensile properties, than does a Be addition alone or with other additions. The probable reason for good mechanical properties, even in the case of higher-Fe-containing alloys containing a Be addition can be explained as follows: The Be-Fe phases are present inside the α-Al dendrites and act as a preferential site for crack nucleation rather than the Si particles. However, these nucleated cracks are arrested when they approach the α-Al dendrites.     

EFFECT OF Ce ON SOLIDIFICATION STRUCTURE OF LOW SULPHUR 16 Mn STEEL

采用定向凝固工艺考察了Ce对低硫16Mn钢一次结晶的影响.结果表明,Ce作为溶质元素的合金化作用,使胞晶间距增大,二次枝晶臂间距变小,柱状晶区缩短,等轴晶粒细化,并使Mn的显微偏析减少.采用此工艺可以排除晶体固一液界面附近的夹杂物对凝固形貌的影响.     

The influence of tempering temperature,minor alloying elements,and cathodic polarization on the low frequency fatigue resistance of 18% Ni maraging steel

The low frequency fatigue resistance of 18% Ni maraging steel (G110) under environmental conditions conducive to hydrogen embrittlement was altered by changes in the S, P, Mn and Cu minor element contents. The detrimental effect of increasing the S, P or Mn contents independently could be reversed when they were in combination, owing to beneficial interactions between Mn and S and Cu and P.Tempering the G110 maraging steel at higher temperatures (500–650°C) reduced the hardness and increased the amount of retained austenite, with a consequent improvement in the hydrogen embrittlement resistance.     

Effect of alloy grain size and silicon content on the oxidation of austenitic Fe-Cr-Ni-Mn-Si alloys in pure O2

Austenitic Fe-18Cr-20Ni-1.5Mn alloys containing 0, 0.6, and 1.5 wt.% Si were produced both by conventional and rapid solidification processing. The isothermal and cyclic oxidation resistance of the alloys were studied at 900°C in pure O₂ to elucidate the role of alloy microstructure and Si content on oxidation properties. The conventionally-processed, large-grained alloy that contained no silicon formed Fe-rich nodules during oxidation. The nodule formation was effectively eliminated by either reducing the alloy grain size by rapid solidification or by adding Si to the alloy. The lowest weight gains were achieved when a continuous silica layer formed between the alloy and the external chromia scale. The formation of the continuous silica layer required a ombination of fine alloy grain size and high Si content. The presence of S in the alloy was found to be detrimental to oxide scale adherence when the silica layer was continuous.     

Effect of Mn Content on Microstructure and Cryogenic Mechanical Properties of a 7% Ni Steel

The effect of Mn content on the microstructure and cryogenic mechanical properties of a 7% Ni steel was investigated within the Mn content range from 0.13% to 0.36%. The microstructure of the steel as determined by optical microscopy,scanning electron microscopy, transmission electron microscopy, electron backscattering diffraction and X-ray diffraction was presented, and the low-temperature mechanical properties were given. The size of prior austenite grain did not change a lot as Mn content increased. Film-like reversed austenite, having high stability, was found mainly in the specimens with lower Mn content; however, in the specimen with the highest Mn content, the role of Mn was not obvious in stabilizing reversed austenite. Besides, with increasing Mn content, the amount of reversed austenite at grain boundaries gradually decreased. The variable Mn content had a significant effect on cryogenic toughness, but not apparent on cryogenic tensile strength or yield strength. An excellent combination of cryogenic tensile and impact properties was obtained when Mn content of steel was 0.13%.     

Mn含量对共晶Al-2％Fe合金组织的影响

研究了含Mn量对共晶Al-2％Fe合金组织的影响。结果表明，在Al-2％Fe合金中加入Mn后，其组织中出现了先析相(FeMn)Al6，且随着Mn量的增加，先析相的数量增加,当Mn量增加到一定程度后，先析相出现发达的分枝。文中还对Mn的影响机理进行了探讨。     

Mn含量对Mg-Zn-Mn变形镁合金显微组织和力学性能的影响

通过对3种不同Mn含量的Mg-6Zn-XMn变形镁合金的微观组织的观察及力学性能的测定,研究了Mn含量对Mg-Zn-Mn镁合金显微组织和力学性能的影响。结果表明：Mn元素以单质形式弥散地分布于Mg-Zn-Mn合金中,起到阻碍晶粒长大的作用,即随着Mn含量的增加,晶粒尺寸减小;Mn含量的变化对合金的屈服强度有一定的影响,即随着Mn含量的增加,屈服强度增加,其中挤压态增幅最大,双级时效次之,增幅分别是14%和5%;而Mn含量的变化对T6、T4+双级时效后合金的抗拉强度和延伸率的影响规律不明显,其中含0.68%Mn(质量分数, 下同)的合金整体性能较优,经双级时效后具有最高抗拉强度,达到360 MPa,伸长率为5.2%