高强度奥氏体不锈钢的热变形行为及其热加工图

从工业生产的不锈钢大型锻件上取样,在应变速率0.01～10s-1、变形温度850～1250℃条件下采用Gleeble3500热模拟试验机进行了压缩热变形试验,研究了一种高强度奥氏体不锈钢热变形力学行为和再结晶规律,测得热变形激活能为455kJmol,并列出了这种高强度奥氏体不锈钢的热变形方程ε=4.173·1016[sinh(α·σp)]4.06exp-455000RT。基于动态材料模型建立了其在常见形变量之下的热加工图(ProcessingMap)。试验结果说明,该奥氏体不锈钢具有较高的动态再结晶温度,在1150℃变形能量消耗效率达到最大值0.4。     

氮对半高速钢奥氏体冷却转变动力学的影响

研究加氮和不加氮的两种半高速钢（低合金高速钢）的奥氏体冷却转变动力学行为,建立并对比分析两种钢的连续冷却转变图（CCT图）。采用图象分析仪和扫描电镜以及能谱仪（EDS）分析了淬火加热的碳化物数量及成分的变化规律。结果表明,加氮的半高速钢中氮化物相对含有较多的V、W、Mo和较少的Cr元素,淬火加热时表现出较高的稳定性;氮的添加使Ac1和Ms／Mf温度下降,显著提高了淬透性。     

含氮Cr-W-Mo-V半高速钢回火过程中的沉淀析出行为

进行了Cr-W-Mo-V(%:46Cr-24W-24Mo-1.52.0V)系和Cr-W-Mo-V+N(0.05%0.10%)系半高速钢(Semi-HSS)1050℃淬火后分别在100~600℃两次回火沉淀析出行为的研究。采用透射电镜、扫描电镜及能谱仪和能量损失谱对碳化物形貌和成分进行分析,用X射线衍射法测定残余奥氏体的体积分数。结果表明,氮有增强钢的二次硬化的效果,氮促进碳氮化物在425~475℃回火析出,在550℃回火碳化物依附在氮化物表面而沉淀形成复合碳氮化物。Semi-HSS+N在淬火及400℃以下回火,残余奥氏体为15%~17%;随回火温度增加,残余奥氏体量急剧降低,在525℃回火残余奥氏体小于3%。     

固溶态316LN不锈钢的氧化行为

研究了固溶态316LN不锈钢在900～1200℃空气中的氧化行为。结果表明,316LN不锈钢在900～1200℃范围内氧化增重与氧化时间的关系遵从抛物线规律,氧化速率常数kT随温度的升高而增大;316LN不锈钢的高温氧化具有选择性,氧化首先发生于富Cr的晶界处;900℃时氧化轻微,氧化膜主要为Cr2O3,1000℃时氧化膜组成为Cr2O3和尖晶石结构的MnCr2O4,1200℃时除Cr2O3和MnCr2O4外,还存在少量的FeCr2O4。316LN不锈钢的氧化激活能为278.765 kJ/mol,氧化速率常数为8.05×105exp{-278265/(RT)}。     

Effect of rare earth elements on the thermal cracking resistance of high speed steel rolls

The effect of rare earth elements on the thermal cracking resistance of high speed steel (HSS) rolls was investigated. Laser rapid heating was used for thermal fatigue experiments. Thermal cracks and microstructure were observed using metalloscopy and scanning electron microscopy. The results showed that thermal cracks initiated from the interface between the matrix and eutectic carbides (including M6C and M7C3 type carbides),and propagated along the interface between the two phases. MC type carbides enriched with vanadium could prevent the propagation of thermal cracks. The presence of rare earth elements decreased the quantity of big eutectic carbides,and proportionally increased spherical and rod-shaped MC type carbide content. HSS0 (0.00% RE) had approximately three times the thermal cracking density of HSS3 (0.12 wt.% RE). Rare earth elements were shown to significantly improve the microstructure and thermal cracking resistance of HSS rolls.     

热处理对Cu-Cr-Zr合金抗拉强度的影响

研究了固溶和时效热处理对Cu-Cr-Zr合金抗拉强度的影响.结果表明：热处理对Cu-Cr-Zr合金抗拉强度有较大的影响,当CuCrZr合金经1040 ℃固溶处理后再经480 ℃保温4 h时效处理可获得较高的抗拉强度.     

改进型无限冷硬铸铁轧辊回火组织转变研究

通过对改进型无限冷硬铸铁轧辊不同回火温度和时间的系列回火试验,用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等分析手段,研究回火对铸态组织中亚稳残余奥氏体转变的影响,分析铸态下贝氏体在组织回火中的分解及碳化物析出行为。试验结果表明：改进型无限冷硬铸铁350℃以下温度回火后奥氏体仍然稳定存在;425～450℃温度问回火在下贝氏体针内部析出合金渗碳体,大部分奥氏体转变为上贝氏体组织;500℃回火后得到回火索氏体组织。     

高压多级离心泵接合面泄漏的消除

高压多级离心泵接合面密封的好坏,直接关系到泵的安全运行。接合面一旦出现泄漏,不仅损耗给水,脏污运行现场,而且容易导致泄漏处零件材料的冲损。一般虽经更换垫片就可以使用,但严重时就要焊补接合面、车床加工及研磨,这样都要被迫停役,解体检修,给检修工作带来了许多麻烦。     

Effect of RE on molybdenum partitioning and resultant mechanical and microstructuralbehaviorofaduplexstainlesssteelduringhotworkingcondition

The effect of rare earth(RE) on Mo partitioning and resultant mechanical and microstructural behavior of a duplex stainless steel during hot working condition was investigated. It was found that RE effect was sensitive to temperature. At the high temperature, the development of dynamic recovery(DRV) in α phase was slowed down while the dynamic recrystallization(DRX) process in γ phase was accelerated by RE, whereby both work hardening rate(at low strain) and dynamic softening rate(at high strain) increased and moreover, the discrepancy on the hardness of the both phase reduced. Whereas at the low temperature, the effect of RE was opposite as compared with those in the high temperature. Mo partitioning analysis by EPMA indicated that RE enhanced the partitioning of Mo in α phase while reduced Mo concentration in γ phase at higher temperature whereby the mismatch between two phases could be improved indicated by the elimination of voids and cracks at α/γ interface, but it was contrary to that at the low temperature. Mo partitioning was believed to be an important cause for the RE effect on the differences of mechanical and microstructural behavior. Also this result provided a reasonable evidence for micro-alloying of RE in DSSs.