Effect of Cr–Mo Addition on the Microstructure and Mechanical Properties of Medium-Carbon Steel

Herein, the effects of Chromium–Molybdenum (Cr–Mo) addition on the microstructural evolution and mechanical properties of medium-carbon steel after spheroidization annealing are systematically studied through scanning electron microscopy, electron backscatter diffraction, and tensile testing. Cr–Mo addition hinders the proeutectoid ferrite + pearlite transformation, thereby promoting the bainite transformation. Moreover, it refines the pearlite lamellar spacing as well as decreases the average carbide diameter, increases the number of carbides per unit area, and hinders ferrite recrystallization. Compared with those in the B1 steel annealed for 8 h, the size of carbides and their number per unit area in the CM1 steel are 30% lower and 2.2-fold higher, respectively. Due to finer ferrite grains, smaller carbides, and a higher amount of carbides, the strength of steel improves, and the plasticity slightly reduces after Cr–Mo addition. After 2 h of annealing, the yield strengths of Cr–Mo steels are 77.5–109.5 MPa higher than those of base steels; the elongations are above 20%. The contributions of the strengthening mechanism of steel to the yield strength are as follows (from high to low): grain boundary, precipitation, solid solution, and dislocation strengthening.     

Effect of Bonding Temperature on Microstructure and Mechanical Properties of WC–Co/Steel Diffusion Brazed Joint

In this work, the diffusion brazing of AISI 4145 steel to WC–Co cemented carbide using RBCuZn-D interlayer with bonding temperature values of 930, 960, 990 and 1020 °C was studied. The microstructure of the joint zone was evaluated by scanning electron microscope (SEM) and X-ray diffraction (XRD). Vickers microhardness and shear strength tests were performed to investigate mechanical behaviors of the brazed joints. The XRD and SEM results indicated that with increase of bonding temperature, the elements readily diffused along the interface and formed various compounds such as γ, α and β and Co₃W₃C. The results also showed that with the increase of bonding temperature from 930 to 960 °C, a sound metallurgical bond was produced, however in higher bonding temperatures (990 and 1020 °C) a decrease in mechanical properties of the joints was observed which could be due to the excessive zinc evaporation, interface heterogeneity and voids formation. The maximum shear strength of 425 MPa was obtained for the bond made at 960 °C.     

Understanding the Effect of a Paint Bake Cycle on the Microstructure–Mechanical Properties Relationship of a Resistance Spot Welded Advanced High Strength Steel

Metallurgical and Materials Transactions A - The effect of an automotive paint bake (PB) thermal cycle on the microstructural evolution and the mechanical properties of resistance spot welded...     

Microstructure and Mechanical Properties of the Ductile Al–Ti–Mo–Nb–V Refractory High Entropy Alloys

Metallurgical and Materials Transactions A - A number of non-equimolar refractory high entropy alloys (RF HEAs) from the Al–Ti–Mo–Nb–V system are synthesized, with the...     

Effect of V–Nb Composite Microalloying on Microstructure and Properties of Non-Quenched and Tempered Forged Steel

Herein, non-quenched and tempered forging steels containing V and V–Nb are designed, and the mechanical properties and microstructure of two steels are compared and analyzed. The comprehensive mechanical properties of V–Nb containing steel are as follows: the yield strength is 525.1 MPa, the impact energy A_kV is 62.1 J at ambient temperature, and the elongation is 26.1%. It is shown in the results that the addition of Nb element can refine the grain size (17.2 μm), increase the ferrite content (54.1%), and refine the lamellar spacing of pearlite (274 nm). The formation of V (C, N) particles on MnS inclusions can promote fine ferrite nucleation and growth, and Nb element can further promote ferrite nucleation by forming coarser (V, Nb) (C, N) particles. The difference of yield strength and hardness between the two steels is mainly caused by the difference of precipitation strengthening, the precipitation-strengthening increment of V–Nb containing steel is 18.31 MPa higher than that of V containing steel, which is because the coarser-size (V, Nb) (C, N) particles produce stronger precipitation-strengthening effect. But the large-sized MnS inclusions are beneficial to the increase of crack driving force and reduce the plasticity and toughness.     

Effect of Yttrium on Mechanical Properties and Microstructure of Ceramets

ＥｆｆｅｃｔｏｆＹｔｔｒｉｕｍｏｎＭｅｃｈａｎｉｃａｌＰｒｏｐｅｒｔｉｅｓａｎｄＭｉｃｒｏｓｔｒｕｃｔｕｒｅｏｆＣｅｒａｍｅｔｓＬｉｕＮｉｎｓ（刘宁）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇ，ＡｎｈｕｉＩ...     

Development of TiMicroalloyed 600 MPa Hot Rolled High Strength Steel

 A high strength steel with tensile strength on the order of 710MPa had been development successfully with only addition of titanium alloy element based on a low carbon steel. The results show the hot deformation accelerates ferrite and pearlite transformation and retards bainite transformation under continuous cooling condition. The microstructure of this steel is mainly composed of fine-grained ferrite and carbides distributed along the ferrite grain boundaries. The yield and tensile strengths of steels are about 620～650MPa and 720～740MPa, respectively, and the values of strain hardening exponent (n) and plastic strain ratio (r) are 0.12 and 0.80, respectively, thus providing well-matched strength with toughness. In short, the fine-grained ferrite and TiC nano-precipitates play an effective role in strengthening the steel.     

Effect of the Intercritical Annealing Temperature on the Mechanical Properties of 10 Pct Mn Multi-phase Steel

Intercritically annealed 10 pct Mn steel has been shown to exhibit an excellent combination of strength and ductility due to the plasticity-enhancing mechanisms of mechanical twinning and strain-induced martensite transformation occurring in sequence. This mechanical behavior is only achieved for a multi-phase microstructure obtained after annealing within a specific intercritical temperature range. A model for the selection of the optimal intercritical annealing temperature was developed to achieve a high strength-ductility balance for 10 pct Mn multi-phase steel. The model considers the room temperature stacking fault energy and the thermodynamic stability of the retained austenite.     

Effect of Adding Nitrogen on Microstructure and Property of Vanadium Microalloyed Reinforcing Bar Steel

Worldwideattentionhasbeenpaidtomicroal loyedsteelwhichhasbeendevelopedrapidly .Manyadvantagesofmicroalloyedsteelhavebeenrecog nizeddeeply .Firstly ,themicroalloyedsteelhashighstrengthand goodcomprehensiveproperties .Sec ondly ,highprofitscanbegainedduetolowerpro ductionandapplicationcost .Themicroalloyingele mentsareaddedtomicroalloysteelsforgrainrefin ingandprecipitationstrengthening[1] .　　Theabilityofsecondphaseparticlestomaintainfinegrainsizesathightemperaturebypinningmi gratingboundarie…     

Effect of RE-Modifier on Microstructure and Mechanical Property of High-Carbon Medium-Manganese Steel

Ｌｉｎｉｎｇｐｌａｔｅｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｗｅａｒ ｒｅｓｉｓｔａｎｔｃｏｍｐｏｎｅｎｔｓｏｆｂａｌｌｍｉｌｌｓ .Ｉｔｍｕｓｔｍｅｅｔｖａｒ ｉｏｕｓｒｅｑｕｉｒｅｍｅｎｔｓｆｏｒｔｈｅｍａｃｈｉｎｅｓａｃｃｏｒｄｉｎｇｔｏｏｐ ｅｒａｔｉｎｇｃｏｎｄｉｔｉｏｎｓ .Ｒｅｃｅｎｔｌｙ ,ａｓｅｒｉｅｓｏｆｗｅａｒ ｒｅｓｉｓ ｔａｎｔｍａｔｅｒｉａｌｓｈａｓｂｅｅｎｄｅｖｅｌｏｐｅｄｆｏｒｄｉｆｆｅｒｅｎｔｂａｌｌｍｉｌｌｓｉｎＣｈｉｎａ ,ｅ .ｇ .ｈｉｇｈ ｃａｒｂｏｎｍｅｄｉｕ…     

Effect of Microstructure and Mechanical Properties of Al–Mg Alloy Processed by ECAP at Room Temperature and Cryo Temperature

This research primarily focuses on improving the strength of Al 5083 alloy by both the ECAP and Cryo ECAP methodology. Equal Channel Angular Pressing (ECAP) is one of the best technologies that enable the direct transformation of conventional macro grained metals into sub-micron, ultra-fine and nano grained materials. Fine grain size increases the strength and the fracture toughness of the material and provides the potential for super plastic deformation at moderate temperatures and at high strain rates. The microstructure evolution in Al 5083, subjected to Room Temperature ECAP and Cryo ECAP were analysed. ECAP was carried out using an optimized die with Channel angle ‘?’ = 90°and corner angle ‘Ψ’ = 20° through processing route A and C up to four passes. The results were thoroughly studied using TEM, SEM, and optical microscopic images. Initially the annealed sample had the grain size of 80 µm with the equi-axed grains. In Room Temperature, the hardness values and the mechanical strength were found to be increased from 88 to 410 HV and 306 to 453 MPa after four passes in route A and in route C the strength increased from 390 to 416 MPa after four ECAP passes. Moreover, in Cryo Condition, the sample was processed up to four ECAP passes at route A and route C. The hardness of 153 HV was obtained after four passes in route C and 164 HV obtained after four passes on route A. Additionally, fracture behaviour using SEM, grain size using TEM and crystallite size by X-ray diffraction studies were analyzed. It was observed that the Cryo ECAP showed marginal improvements in mechanical properties relative to the RT ECAP in case of Al 5083.     

Effect of Ageing at 700 ℃ on Microstructure and Mechanical Properties of S31042 Heat Resistant Steel

 To investigate the effect of high temperature ageing on the microstructure and mechanical properties of S31042 steel, solid solution treatment at 700 ℃ was carried out for various time from 10 to 6000 h. Experimental results showed that the change of mechanical properties is closely related to the amount of precipitated phases. During ageing from 10 to 300 h, precipitation in the tested steel increases rapidly, and correspondingly, the high temperature yield strength and room temperature hardness of tested steel increase rapidly. Meanwhile, the thickness of the secondary phase on grain boundaries widens sharply and the room temperature Charpy impact absorb energy decreases. Ageing beyond 300 h, the precipitation in the steel increases gradually and the precipitates coarsen to a certain extent. The high temperature yield strength of the steel keeps stable, and the room temperature Charpy impact energy and hardness decrease slowly. Ageing beyond 3000 h, the mechanical properties of the steel tend to be stable. The main precipitates are M23C6, NbCrN and NbC in the tested steel.     

Effect of the Rare Earths on the High Temperature Properties of Deformed Leaded-Brasses

The effect of the rare earths on the high temperature properties of deformed leaded-brasses has been stu-died with the high temperature tensile test.The results show that the rare earth additives can increase elongationof alloys at high temperature,but they had little effect on the maximum flow stress.With the help of SEM.X-ray diffraction instrument,quantitative metallography analysis instrument,etc.,the effect of the rare earthelements on the mierostrueture of alloys has also been examined.     

Microstructure and Mechanical Properties of TRIP Steel with Annealed Martensite

The microstructure and mechanical properties of cold rolled TRIP steel containing C 0.2, Si 0.5, Mn 1.5, A1 1.3, and Nb-kV 0.13 （mass%） with annealed martensite （TAM steel） were investigated using optical microscopy, field emission gun scanning electronic microscope （FEG SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and mechanical testing. The mierostructure of the TAM steel mainly consisted of polygonal ferrite, bainite, annealed martensite and retained austenite. The martensite after annealing did not spheroidize, which consisted of annealed lath martensite structure and interlath second phase. Compared with the traditional TRIP steel with polygonal ferrite matrix （TPF steel）, the TAM steel has more excellent elongation rate over 32%. The TAM steel also has better strain hardening behavior than the TPF steel. The excellent elongation and strain harden- ing behavior of TAM steel result from high retained austenite stability of the TAM steel, which is attributed to its fine distribution and medium strength ratio of second phase to matrix.     

Effect of Flowing Lead–Bismuth Eutectic on the Mechanical and Structural Properties of Stainless Steel 304L

Stainless steel 304L is being considered as a structural material for a component in a critical facility in an environment of molten lead–bismuth eutectic (LBE) at a temperature between 250 and 350 °C. This paper gives results on the effect, of 10,000 h exposure to non-isothermal liquid LBE at temperatures of 250 and 350 °C, on the mechanical and structural properties of SS 304L. The dissolved oxygen concentration in the molten eutectic was 4 × 10^?10 wt% and flow velocity was 16 cm/s. In order to assess the changes in mechanical properties tensile tests were carried out in air at 25 °C and fractography of fractured surface was observed by scanning electron microscopy. The results showed no change in the mechanical properties of SS 304L after 10,000 h exposure to LBE at 250 and 350 °C. Electron probe microanalysis of the interface of SS 304L with LBE showed that there was no penetration of LBE into the grain boundaries nor preferential dissolution of any of the components of steel in LBE after 10,000 h exposure at either temperature. No oxide layer was observed on the surface of SS 304L.     

Effect of Melting Process on the Microstructure and Mechanical Properties of Fe–7 wt% Al Alloy

This article presents the effect of melting process on chemical composition, microstructure and mechanical properties of Fe–7 wt% Al alloy. The alloy ingot was prepared by air induction melting (AIM), air induction melting with flux cover (AIMFC) and vacuum induction melting (VIM) and cast into 50 mm diameter split cast iron mould. These cast ingots were hot-forged and hot-rolled at 1,373 K to 2 mm thick sheet. Hot-rolled alloys were characterized with respect to chemical composition, microstructure and mechanical properties. Ingots produced by AIM, AIMFC and VIM were free from gas porosity, however AIM ingots exhibited higher concentration of hydrogen as compared to AIMFC and VIM. The recovery of aluminium as well as reduction of oxygen during AIM is very poor as compared to AIMFC and VIM. AIMFC ingots exhibit low level of sulphur as compared to AIM and VIM ingots. The alloys produced by AIMFC and VIM exhibited superior tensile ductility compared to the alloys produced by AIM. The tensile properties of alloys produced by AIMFC are comparable to the alloys produced by VIM.     

Effect of Heat Treatment Process on Mechanical Properties and Microstructure of Modified CNS-Ⅱ F/M Steel

 Ferritic/martensitic (F/M) steels have been recommended as one of the candidate materials for supercritical water cooled reactor (SCWR) in-core components use for its high thermal conductivity, low thermal expansion coefficient and inherently good dimensional stability under irradiation condition in comparison to austenitic steel. CNS-Ⅱ F/M steel which has good mechanical properties was one of the 9-12Cr F/M steels designed for SCWR in the previous work. In this study a modified CNS-Ⅱ F/M steel was used and it′s ultimate tensile strength was 925 MPa at room temperature and 483 MPa at 600 ℃ after optimizing heat treatment parameter. The ductile to brittle transition temperature of modified CNS-Ⅱ F/M steel is -55 ℃. Those are at the same level or even higher than that of CNS-Ⅱ and some commercial F/M steels nominated for SCWR in-core component use. The transmission electron microscope (TEM) results showed that the mechanical properties of the tempered martensite was closely related to the decomposition stage of the martensite.