EBSD Study of Microstructural and Textural Changes of Hot-Rolled Ti-6Al-4V Sheet After Annealing at 800 °C

In this paper, electron backscatter diffraction and various other characterization and analysis techniques including X-ray diffraction, electron channeling contrast imaging and energy-dispersive spectrometry were jointly employed to investigate microstructural and textural changes of a hot-rolled Ti-6Al-4V (TC4) sheet after annealing at 800 °C for 5 h. In addition, the hardness variation induced by the annealing treatment is rationalized based on revealed microstructural and textural characteristics. Results show that the TC4 sheet presents a typical dual-phase (α?+?β) microstructure, with α-Ti as the major phase and short-rod-shaped β-Ti (minority) uniformly distributed throughout the α matrix. Most of α grains correspond to the un-recrystallized structures with a typical rolling texture (c//TD and <11-20>//ND) and dense low angle boundaries (LABs). After the annealing, the stored energy in the as-received specimen is significantly reduced, along with greatly decreased LABs density. Also, the annealing allows recrystallization and grain growth to occur, leading to weakening of the initial texture. Furthermore, the water quenching immediately after the annealing triggers martensitic transformation, which makes the high-temperature β phases be transformed into submicron α plates. The hardness of the annealed specimen is 320.5 HV, lower than that (367.0 HV) of the as-received specimen, which could be attributed to reduced LABs, grain growth and weakened texture. Nevertheless, the hardening effect from the fine martensitic plates could help to suppress a drastic hardness drop.     

Typical Microstructural Characteristics of Ti-5Al-5Mo-5V-3Cr-1Fe Metastable βTi Alloy Forged in α+β Region

In this study, typical microstructural characteristics of a metastable β Ti alloy (Ti-5Al-5Mo-5V-3Cr-1Fe) forged in a dual-phase region (strain of 54% at 820 °C) were investigated in detail by the combined use of X-ray diffraction, energy dispersive spectroscopy, electron channeling contrast imaging and electron backscatter diffraction techniques. Results show that the microstructure of the forged alloy is composed of bulk α grains, α plates and β matrix. The bulk α grains correspond to retained primary α phase (α_p, average grain size~2.4 μm), while the α plates are secondary α phase (α_s, width~70 nm) precipitated from the β matrix during air cooling. During forging, the β matrix experiences dynamic recovery with many subgrains and significant orientation gradients formed. Analyses of the orientation relationship between the α and β phases show that the Burgers orientation relationship is not maintained between some α_p and β phases, which should be related to thermal deformation-induced changes of their orientations. In contrast, all of the α_s plates are found to maintain well the Burgers orientation relationship with the β phase.     

Designing Rules of Laser-Clad High-Entropy Alloy Coatings with Simple Solid Solution Phases

The criteria of process parameters(μ≤4),atomic size difference(ε≤5.8,δ≤11 and α≤2),thermodynamic(-14.5 ≤△H_(mix)≤6.5 and Ω≥ 1.8) in the prediction of the phase stability for laser-clad high-entropy alloy coatings are studied in detail.Besides,the criteria of valence electron concentration(VEC) applied to distinguish the stability of different solid solution phases are as follows:VEC7.65 for simple BCC,VEC≥7.65 for simple face-centered cubic(FCC),7.14 VEC 7.78 for dual-phase BCC and FCC.Among them, μ and ε proposed firstly separate the phase stability of laserclad high-entropy alloy coatings quite precisely.The other modified criteria(δ,α,△H_(mix),Ω,VEC) are proved to be different from those of the high-entropy alloys synthesized by the traditional casting and smelting processes.     

Different Mechanisms of ε-M and α'-M Variant Selection and the Influencing Factors of ε-M Reversion During Dynamic Tension in TRIP Steel

The variant selection of martensites(ε-M and α'-M) and ε-M reversion in dynamic tensile high-manganese TRIP steel were investigated. α'-M variant pairs with a zigzag morphology frequently formed, and the pairs of neighboring α'-M variants were examined in terms of mechanical work and strain energy reduction. The occurrence of a primary α'-M variant is determined by mechanical work, but high products of mechanical work and strain energy reduction are essential for secondary variant selection. In contrast to α'-M variant pair selection, ε-M variant selection can be attributed to the highest mechanical work. During ε-M→α'-M transformation, the mechanical work of ε-M reversion is higher than that of α'-M variant, thereby implying that ε-M reversion in h110 icgrain is possible. e-M plate distribution also affects the feasibility of ε-M reversion.     

Element Segregation and Solidification Behavior of a Nb,Ti, Al Co-Strengthened Superalloy ЭК151

The as-cast microstructure, element segregation and solidification behavior of a multi-alloyed superalloy ЭК151 have been investigated. The results show that the severe element segregation leads to the complicated precipitations at the inter-dendritic region, including η-Ni_3(Ti, Nb), eutectic(γ + γ') and Laves, which shows the characteristics of both Ti, Al-strengthened and Nb-strengthened alloys. Differential thermal analysis, heating and quenching tests reveal the solidification sequence as follows: Liquids →γ matrix →(Nb, Ti)C →η-Ni 3(Ti, Nb) →eutectic( γ+γ') → Laves. The melting points are between 1250 and 1260 °C for(Nb, Ti)C, between 1200 and 1210 °C for η phase, between 1180 and 1190 °C for eutectic(γ+γ') and Laves. γ' initially precipitates from matrix at 1150 °C and achieves the maximum precipitation at 1130 °C. According to the microstructure evolution captured during solidification and composition analysis by an energy dispersive spectrometer and electron probe microanalyzer,(Nb, Ti)/Al ratio is put forward to explain the formation of η-Ni_3(Ti, Nb) and eutectic( γ+γ'). The solidification of γ matrix increased the Nb, Ti concentration in the residual liquids, so the high(Nb, Ti)/Al ratio would result in the formation of η-Ni_3(Ti, Nb); the precipitation of the phase consumed Nb and Ti and decreased the(Nb, Ti)/Al ratio in the liquid, which led to the precipitation of eutectic(γ + γ'). Laves formed by the sides of η-Ni_3(Ti, Nb) and in front of the eutectic( γ + γ') after Al, Ti were further depleted by the two phases and Cr, Co, Mo were rejected to liquids.     

Crystallographic Texture Evolution of ■-Fe_4N and Its Influences on Tribological Property of Nitrided Steel

The crystallographic texture of ■-Fe4 N in compound layer and its influences on the tribological properties of nitrided steel 38 Cr Mo Al are investigated in the study. The preferred orientation of(200)■ is produced by low-temperature nitriding in atmosphere with low nitrogen–hydrogen ratio and increases with the nitriding time. The preferred orientation of(220)■ appears after 72 h cyclic nitriding. The orientation relationships(0001)_ε//(101)_■ and [110]_ε//[111]_■,(111)_■//(0001)_ε and 011_■//[1■10]_g,(200)■//(110)_■ and [011]_■//[111]_■, as well as (1■03)_ε //(220)_■ and [0100]_ε//[1■0]_■ are established by first-principles method. The misfit of interatomic distance(δ), determining the phase transition resistance, is calculated. Accordingly, two reaction pathways during nitriding, ■→■ and ■→ε→■, are assumed, which determines the preferred orientations of ■-Fe_4 N. Results of wear tests demonstrate that the specimen with preferred orientation of(200)■ exhibits lower frictional coefficient and lower wear rate in comparison with the specimen with(220)■ preferred orientation.(111)■ texture usually relates to the lower frictional coefficient but higher wear rate due to the main slip system parallel to the sliding plane. Therefore, the(200)■ preferred orientation has a positive significance in improving the wear properties of steels.     

Creep-Induced Phase Instability and Microstructure Evolution of a Nearly Lamellar Ti-45Al-8.5Nb-(W,B,Y)Alloy

Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated. Tensile creep experiments were performed at 800, 850 and 900 °C under 150 MPa in air. Microstructures before and after creep tests were examined using scanning and transmission electron microscopy (SEM and TEM). Dislocations within the lamellar structure and β_o(ω) region and twin intersection in massive γ grains were investigated. Dislocation sliding played a critical role in the deformation of ω_o phase, which preferentially occurred on the (0002)ω_o plane. Possible deformation mechanisms were revealed. A stress-induced γ→α₂ phase transformation took place during the creep test at 850 and 900 °C. α₂ lamella could directly decompose into the ω_o phase at 850 °C. The instability of high-temperature microstructure can weaken the creep resistance and promote the plastic deformation of the lamellar matrix, thus could be detrimental to the creep properties. The correlations between creep properties and microstructure instability were discussed.     

Microstructural Instability of an Experimental Nickel-Based Single-Crystal Superalloy

Microstructural instability with the precipitation of topologically close-packed (TCP) phases of an experimental nickel-based single-crystal superalloy has been investigated. A significant amount of σ phases are distinguished in the interdendritic region of the as-cast samples after thermal exposure at 900 °C for 1000 h. The σ phases are preferentially precipitated at the periphery of coarse γ/γ′ eutectic, and their morphological evolution from needles to granules is observed. Microstructural analysis suggests that the local segregation of Cr and Ti at the periphery of coarse γ/γ′ eutectic accounts for the formation of σ phases in the as-cast samples. After heat treatment with low solution temperature and short holding time, the dendritic segregation of alloying elements (i.e., W, Re, Ti and Ta) and the volume fraction of γ′ phase in the interdendritic region are similar to that of the as-cast samples. However, no TCP phases are present in the interdendritic region of the heat-treated samples after thermal exposure, which is primarily ascribed to the elimination of local segregation of Cr and Ti near the coarse γ/γ′ eutectic. Moreover, small quantities of μ phases are precipitated in the secondary dendrite arm near the interdendritic region after thermal exposure, due to the increased volume fraction of γ′ phase and the concomitant enrichment of W and Re in the γ matrix.     

Effect of Co on Microstructure and Stress Rupture Properties of K4750 Alloy

The effects of substituting Co for Fe on the microstructure and stress rupture properties of K4750 alloy were studied.The microstructure of the alloy without Co(K4750 alloy) and the alloy containing Co(K4750-Co alloy) were analyzed.Substitution of Co for Fe inhibited the decomposition of MC carbide and the precipitation of η phase during long-term aging treatment.In K4750-Co alloy,the morphology of MC carbide at the grain boundary(GB) remained dispersed blocky shape and no η phase was observed after aging at 750℃for 3000 h.However,in K4750 alloy,almost all the MC carbides at GBs broke down into granular M_(23)C_6 carbide and needle-like η phase.The addition of cobalt could delay the decomposition of MC carbides,which accordingly restricted the elemental supply for the formation of η phase.The stress rupture tests were conducted on two alloys at 750℃/430 MPa.When Co is substituted for Fe in K4750 alloy,the stress rupture life increased from 164.10 to 264.67 h after standard heat treatment.This was mainly attributed to increased concentration of Al,Ti and Nb in γ' phase in K4750-Co alloy,which further enhanced the strengthening effect of γ' phase.After aging at 750℃for 3000 h,substitution of Co for Fe can also cause the stress rupture life at 750℃/430 MPa to increase from 48.72 to 208.18 h.The reason was mainly because MC carbide degradation and η phase precipitation in K4750 alloy,which promoted the initiation and propagation of micro-crack during stress rupture testing.     

Effect of Different Scale Precipitates on Corrosion Behavior of Mg–10Gd–3Y–0.4Zr Alloy

A large amount of directional and willow-like β' phase was precipitated in Mg-10 Gd-3 Y-0.4 Zr(GW103 K) alloy after solution treatment and subsequently aged treatment(T6). In order to explore the effect of the precipitates on the corrosion behavior of the GW103 K alloy, the alloy was subjected to solution treatment(T4) at 773 K for 4 h at first, subsequently aged at 498 K for 193 h(T6). The microstructure evolution of the GW103 K alloy after this treatment was investigated by scanning electron microscopy and transmission electron microscopy. The high-angle annular detector dark-field scanning transmission electron microscopy was used to observe the typical corrosion morphologies of the nanoscale precipitation phases(β') in the T6-treated alloy. The corrosion rate was measured by potentiodynamic polarization test. Combining with the potential measurement results by scanning Kelvin probe force microscopy, the effects of the skeleton-like Mg_(24)(Gd,Y)_5 andf precipitates on the corrosion behavior of GW103 K alloy were explored. The results showed that the corrosion rate of the GW103 K alloy in different conditions was ranked as: as-cast alloy T4-treated alloy T6-treated alloy,attributing to the fact that the relative potential differences of skeleton-like Mg_(24)(Gd,Y)_5 were lower than those of the matrix, therefore Mg24(Gd, Y)5 phase formed micro-galvanic coupling with the matrix and corrosion dissolution occurred.The nanoscale β' precipitates in T6-treated alloy can retard the cathodic process.     

Role of Ru on the Microstructural Evolution During Long-Term Aging of Ni-Based Single Crystal Superalloys

Two experimental alloys containing different contents of Ru were investigated to study the effect of Ru on the microstructural evolution during long-term thermal exposure. The increase in Ru promoted the formation of cubical, tiny, and even γ′ phase after full heat treatment. Moreover, the samples after full heat treatment were exposed at 1100 °C for different time. Based on the classical model by Lifshitz, Slyozov, and Wagner, the coarsening of γ′ phase of the alloy containing 2.5 and 3.5 wt.% Ru during the long-term aging was controlled by the interface reaction and diffusion, respectively. The γ/γ′ lattice misfit was more negative with the increment of Ru addition, which induced the formation of stable rafted γ′ phase in the alloy containing 3.5 wt.% Ru at the initiation of long-term aging. Besides, the increase in Ru reduced the diffusion coefficient, which could restrain the γ′ phase coarsening. The lower γ/γ′ lattice misfit of the alloy containing 2.5 wt.% Ru promoted the interface reaction, which induced the rapid coarsening of γ′ phase. Therefore, the increase in Ru improved the microstructural stability of the alloys. On the other hand, the raise of Ru induced “reverse partitioning” behavior, which was effective in suppressing the emergence of the topologically close-packed phase (TCP phase). The TCP phase occasionally occurred in the alloy containing 2.5 wt.% Ru, which was attributed to the high temperature and the supersaturation of the γ matrix. Moreover, the TCP phase was determined as μ phase, which had a high concentration of Co, Re, Mo, and W. A sketch map describing the evolution of the TCP phase was also constructed.     

Granular Carbides-Assisted Ultrafine-Ferrite Fabrication in the Pearlitic SteelWithout Severe Plastic Deformation and Annealing

The evolution of ferrite grain and cementite lamella during cold rolling in a granular carbide-pearlite steel has been investigated. Particular attention has been given to a quantitative characterization of changes in the ferrite grains. Electron back-scattered diffraction and transmission electron microscopy observations show that the ultrafine ferrite (~388 nm) can be produced through low equivalent strain cold rolling without severe plastic deformation (SPD) and annealing. The average grain size of ferrite depends on the volume fraction, shape and distribution of granular carbides as well as interlamellar spacing of pearlite. A general explanation of granular carbides-assisted grain refinement is that the embedded carbides between natural barrier will significantly facilitate dislocation nucleation during cold rolling. Dislocation reaction occurs more drastically and quickly near these granular carbides. Such reactions promote the formation of high-angle grain boundaries. The formation of ultrafine ferrite grains and subgrains in steel after cold rolling to ε=1.4 strain makes the strength and ductility increased simultaneously compared with ε=0.6 cold-rolled steel. The results suggest a new material design strategy to obtain ultrafine-grained structure via the granular carbides assistance.     

Tensile Properties of Cast Alloy IN625 in Relation to d Phase Precipitation

The relationship between the tensile properties and δ (delta) phase precipitation in cast alloy IN625 was investigated in this paper. Although the influences of δ phase on the mechanical properties have been pointed out in our previous work, the relationship is still not directly determined due to the coexistence of γ″ (gamma double prime) and δ precipitates. In order to exclude the effect from γ″ phase, various fractions of δ precipitates with few γ″ precipitates were obtained by a set of experimental alloys aging at 750 °C, and tensile tests were conducted in parallel. The results showed that both yield strength and ultimate tensile strength increased nearly in linear with increasing δ phase fraction, while the elongation was relatively and limitedly affected by δ precipitation when the area fraction of δ phase was above 10%.     

Impacts of Microalloying Elements on the Hardening β"-Phase in Automotive AlMgSi Alloys

Microalloying elements play a crucial role in mechanical properties and phase stability of metallic alloys. In this work, we employ first-principles calculations and atomic-scale high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to find promising microalloying elements that will improve the stability and properties of β"/Al interface and β" phase in Al-Mg-Si alloys. First, we define a substitution energy for evaluating the stability of β" phase and β"/Al interface with microalloying elements doped. Then, experiments of HAADF-STEM imaging are carried out to verify the calculational results. Next, using the most stable structures doped with microalloying elements, the mechanical properties of the β" bulk and the β"/Al interface were calculated and analyzed. At last, we have figured out the effects of all considered microalloying elements and obtained a rule that the stable occupancy of solute atoms is related to their own radius and the radius of Mg, Si, and Al. These findings will provide some theoretical basis for future microalloying strategies of Al-Mg-Si alloys.     

Effect of δ Phase on Microstructure and Hardness of Heat-Affected Zone in TIG-Welded GH4169 Superalloy

The GH4169 superalloy with different content of δ-Ni₃Nb phase was welded by tungsten inert gas welding. A detailed study of microstructure and hardness of heat-affected zone (HAZ) was performed in both as-welded and aged state. The results show that the precipitation of δ phase, especially the intergranular δ phase, can lead to the enrichment of Nb and Mo elements, which promote the formation of γ/Laves eutectic constituent at grain boundaries in HAZ. In as-welded state, the hardness decreases first and then increases (exhibiting a “V” shape) with distance away from fusion line in HAZ, which is governed by grain size. After aging treatment, however, the γ″ phase plays a key role in hardness and leads to the “Λ” shape profiles of hardness in HAZ.     

Microstructure and Size-Dependent Mechanical Properties of Additively Manufactured 316L Stainless Steels Produced by Laser Metal Deposition

Metal additive manufacturing (AM), as a disruptive technology in the field of fabricating metallic parts, has shown its ability to design component with macrostructural complexity. However, some of these functionally complex structures typically contain a wide range of feature sizes, namely, the characteristic length of elements in AM-produced components can vary from millimeter to meter-scale. The requisite for controlling performance covers nearly six orders of magnitude, from the microstructure to macro scale structure. Understanding the mechanical variation with the feature size is of critical importance for topology optimization engineers to make required design decisions. In this work, laser metal deposition (LMD) is adopted to manufacture 316L stainless steel (SS) samples. To evaluate the effect of defects and specimen size on mechanical properties of LMD-produced samples, five rectangular sample sizes which ranged from non-standard miniature size to ASTM standard sub-sized samples were machined from the block. Tensile test reveals that the mechanical properties including yield strength (YS), ultimate tensile strength (UTS), and elongation to failure (ε_f) are almost the identical for samples with ASTM standard size. Whilst, relatively lower YS and UTS values, except for ε_f, are observed for samples with a miniature size compared with that of ASTM standard samples. The ε_f values of LMD-produced 316L SS samples show a more complex trend with sample size, and are affected by three key influencing factors, namely, slimness ratio, cluster of pores, and occupancy location of lack of fusion defects. In general, the ε_f values exhibit a decreasing trend with the increase of slimness ratio. Microstructure characterization reveals that the LMD-produced 316L samples exhibited a high stress status at low angle grain boundaries, whilst its location changed to high angle grain boundaries after plastic deformation. The grain size refinement and austenite-to-martensite phase transformation occurred during plastic deformation might be responsible for the very high YS and UTS attained in this study. The experimental works carried out in this study is expected to provide a guideline for evaluating the mechanical properties of LMD-produced parts with complex structure, where critical parameter such as a certain slimness ratio has to be considered.     

High-Temperature Structural Stabilities of Ni-Based SingleCrystal Superalloys Ni–Co–Cr–Mo–W–Al–Ti–Ta with Varying Co Contents

It has been recently pointed out that the compositions of industrial alloys are originated from cluster-plus-glueatom structure units in solid solutions. Specifically for Ni-based superalloys, after properly grouping the alloying elements into Al, Ni-like(■), r-forming Cr-like(■) and c-forming Cr-like(■), the optimal formula for single-crystal superalloys is established [Al–Ni_(12)](Al_1■~_(0:5) ■_(1:5)). The Co substitutions for Ni at the shell sites are conducted on the basis of the first-generation single-crystal superalloy AM3, formulated as [Al–■_(12)Co_x](Al_1Ti_(0.25)Ta_(0.25)Cr_1W_(0.25)Mo_(0.25)), with x = 1.5, 1.75, 2 and 2.5(the corresponding weight percents of Co are 9.43, 11.0, 12.57 and 15.71, respectively). The900 ℃ long-term aging follows the Lifshitz–Slyozov–Wagner theory(LSW theory), and the Co content does not have noticeable influence on the coarsening rate of c0. The microstructure and creep behavior of the four(001) single-crystal alloys are investigated. The creep rupture lifetime is reduced as Co increases. The alloy with the lowest Co(9.43 Co) shows the longest lifetime of about 350 h at 1050 ℃/120 MPa, and all the samples show N-type rafting after creep tests.     

Synthetic Effect of Cr and Mo Elements on Microstructure and Properties of Laser Cladding NiCrxMoy Alloy Coatings

NiCr_xMo_y (x = 1, 1.5; y = 0, 0.1, 0.3) alloy coatings were prepared on the Q235 substrate by laser cladding under the protection of argon. The phase composition, microstructure, corrosion behavior, and mechanical properties of the NiCr_xMo_y alloy coatings were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electrochemical tests, X-ray photoelectron spectroscopy, microhardness, and nanoindentation tests. As the Cr content increased, the phase composition of the coatings changed from a single face-centered cubic (FCC) structure to a dual-phase structure coexisting with body-centered cubic (BCC) and FCC structures, while the addition of Mo promoted the precipitation of σ phase. The appearance of a homogeneous dual-phase structure and some amount of σ phase played a positive role in the corrosion resistance of NiCr_xMo_y coatings. Cr³⁺ ions and Mo⁶⁺ ions in the passive film enhanced the stability of the coatings. The nanoindentation tests showed that the nanohardness (6.71 GPa) and elastic modulus (184.40 GPa) of BCC phase were higher than those of the FCC phase (5.19 GPa and 155.26 GPa, respectively). Overall, the BCC phase and σ phase improved the mechanical properties of the coatings.     

高铌TiAl/Ti600合金电子束焊接头组织与性能

对高铌TiAl/Ti600合金进行了电子束焊接试验以便对高温钛合金与高铌TiAl合金高质焊接提供理论及试验依据,采用金相显微镜、扫描电子显微镜及X射线衍射仪等设备对焊接试样进行了分析.结果表明,高铌TiAl/Ti600接头极易产生裂纹缺陷.接头焊缝主要形成细针状α₂-Ti₃Al相及α-Ti相,而高铌TiAl侧热影响区呈现板条状及等轴组织形貌,Ti600侧热影响区为针状α'相.接头焊缝区硬度最大,达到586 HV,Ti600侧向高铌TiAl侧过渡过程中硬度逐渐增大,由焊缝到两侧热影响区硬度过渡梯度较大.高铌TiAl/Ti600电子束焊接头室温抗拉强度可达516 MPa,且接头断裂于偏高铌TiAl侧焊缝区,断裂性质为典型的脆性解理断裂,呈现穿晶断裂特征.     

Effect of Ag on the Microstructure,Mechanical and Bio-corrosion Properties of Fe–30Mn Alloy

In the current work, biodegradable Fe–30 Mn– X Ag( X = 1, 2, 5, 10 wt%) alloys were prepared by the rapid solidifi cation with copper-mold-casting technology. Phase analysis demonstrates that Fe–30 Mn– X Ag alloys consist of austenite γ phase with a fcc structure and martensite ε phase with a hcp structure. The yield strength of the samples increases with increasing Ag contents. Compared with Fe–30 Mn alloy, the degradation rates of Fe–30 Mn– X Ag in Hank's solution are signifi cantly improved. Cytotoxicity evaluation reveals that the Fe–30 Mn–1 Ag and Fe–30 Mn–2 Ag alloys perform less toxicity on the Human Umbilical Vein Endothelial Cells(HUVEC), while Fe–30 Mn–5 Ag and Fe–30 Mn–10 Ag alloys perform no toxicity on it. The contact angles of deionized water on the Fe–30 Mn– X Ag alloy surface were ranged from 55° to 69°, which is benefi cial to the adhesion and growth of the cells. Besides, the addition of Ag leads to a much lower M/H slope, particularly for the Fe–30 Mn–5 Ag alloy exhibiting a non-magnetic property as SS316 L. Therefore, the present Fe–30 Mn– X Ag alloys would be potential candidates for degradable metals.