共查询到18条相似文献,搜索用时 171 毫秒
1.
借助于X射线衍射,研究了C、Mn、Cr和Ni 含量对304奥氏体不锈钢拉伸力学性能和应变诱发 马氏体相变倾向的影响。结果表明:C、Mn、Cr和Ni在允许的成分范围内变化,应变诱发α′马氏体相变倾向差异很大,这导致屈服强度和抗拉强度复杂的变化,尽管应变诱发α′马氏体相变使加工硬化速率提高,相变可以诱发塑性,但相变速率较快,相变倾向较大的钢塑性反而下降,此外,由于室温变形还增大热诱发马氏体相变倾向,从而限制了C、Mn、Cr和Ni下限钢在高精度和低温环境下构件的应用。 相似文献
2.
借助于X射线衍射技术,研究了304亚稳奥氏体不锈钢应变诱发马氏体相变倾向对化学成分的敏感性。液氮温度拉伸结果表明:C、Mn、Cr和Ni从标准范围的上限变化到下限,马氏体相变倾向显著增大,加工硬化明显提高。应变诱发α′马氏体相变倾向对C、Mn、Cr和Ni含量很敏感,要控制马氏体相变的发生,可通过优化C、Mn、Cr和Ni含量来实现。 相似文献
3.
304奥氏体不锈钢热诱发马氏体相变研究 总被引:1,自引:0,他引:1
借助X射线衍射技术,研究了304奥氏体不锈钢热诱发马氏体相变倾向.结果表明:C、Mn、Cr和Ni接近标准规范下限,304不锈钢的稳定性急剧下降,致使液氮内冷却后接近1/3的奥氏体转变为α'或ε马氏体,室温拉伸即形成应变诱发ε和α'马氏体,而且较小的室温变形显著增大随后液氮内冷却的热诱发α'马氏体相变倾向,但随室温预应变增大快速形成应变诱发α'马氏体,致使随后在液氮内发生热诱发α'马氏体倾向下降.此外,研究表明ε马氏体的形成及消失与α'马氏体的累积量有关. 相似文献
4.
本文研究了18Ni(2450MPa级)马氏体时效钢的相变超塑性。通过冷变形量、应力以及冷却速度对相变应变影响规律的研究,开发了该合金的相变超塑性成形工艺。当冷变形量为60%时,在最佳工艺条件下,经14cyc γ?α’循环相变,可获得320%的极限延伸率。经TEM观察发现,该合金应力诱发马氏体形态为块状马氏体。 相似文献
5.
用X射线衍射分析、扫描电镜观察以及应变疲劳试验研究表明,Fe-Mn-Si形状记忆合金在承受正负交变应力作用时,可相应地发生应力诱发γ(←→)ε马氏体相变及其逆相变.Fe-Mn-Si形状记忆合金循环变形过程中的应力诱发γ(←→)ε马氏体相变及其逆相变能降低应力集中,抑制塑性滑移变形,减少疲劳裂纹的形成和扩展,使合金具有较高的应变疲劳强度.其弯曲疲劳断口类呈脆性断裂.Fe-17Mn-5Si-10Cr-5Ni试验合金在应变幅值为±1.5%下的应变疲劳寿命达1300次,是U71Mn轨钢和1Cr18Ni9Ti不锈钢的10倍左右. 相似文献
6.
7.
采用OM、EBSD、TEM、XRD和拉伸实验等方法,研究了γ-奥氏体/ε-马氏体双相Fe-19Mn-0.0017C(质量分数,%)合金在拉伸变形过程中的组织演变和加工硬化行为。结果表明,Fe-19Mn发生了变形诱导马氏体相变,并且随着变形量的增加,相变过程由以γ→ε相变为主转变为以ε→α’相变为主。对比分析加工硬化率的变化与相含量的变化,表明ε→α’相变比γ→ε相变具有更高的加工硬化能力。同时,在变形过程中,ε-马氏体不仅发生了位错滑移,还形成了■孪晶,以满足ε-马氏体的变形协调。在γ→ε和ε→α’双重相变引起的相变诱导塑性(TRIP)效应、γ-奥氏体/ε-马氏体/α’-马氏体中的位错滑移,以及ε-马氏体的孪生变形等机制的共同作用下,Fe-19Mn的抗拉强度和总延伸率分别达到722 MPa和31%,显示出良好的强塑性匹配。 相似文献
8.
9.
10.
11.
12.
The tensile properties of 22Cr–2Ni–4Mn–0.2N micro-duplex stainless steels with different Ni and Mn contents were investigated. Duplex stainless steels were vacuum induction melted and hot rolled, then annealed at 1,000–1,100 °C, at which temperature both the austenite and ferrite phases were stable. The volume fraction of the ferrite phase was markedly affected by the alloying elements of Mn and Ni; 1 wt% of Mn was equivalent to 0.4 wt% of Ni. All of the steels tested at room temperature showed the common strain-hardening behavior, while the steels tested at lower temperatures(-30 or-50 °C)showed a distinct inflection point in their stress–strain curves, which resulted from the transformation of the austenite to straininduced martensite. The onset strain(e0) of the inflection point in the stress–strain curve depended on the Md30 value of the steel. Testing at lower temperatures resulted in smaller e0 and consequently higher strengths and fracture strains(ef). The tensile behavior was examined from the perspective of austenite stability of the micro-duplex stainless steels with the different Ni and Mn contents. 相似文献
13.
用600℃时效微观组织变化和冲击韧性的变化评价了1Cr21Ni5Ti双相不锈钢的稳定性。结果表明:1Cr21Ni5Ti双相不锈钢稳定性对Ti/C极为敏感,低Ti/C(Ti/C=4.08)钢600℃时效快速析出富Cr的M23C6碳化物,降低奥氏体内的Cr和C含量致使时效后冷却过程中奥氏体转变为马氏体,并伴随着冲击韧性的严重恶化;而Ti/C适度的钢明显抑制了M23C6碳化物的析出和随后奥氏体向马氏体转变,长时间时效后冲击韧性高出低Ti/C钢近一倍。 相似文献
14.
Ejaz Ahmad Tanvir Manzoor Kanwar Liaqat Ali J. I. Akhter 《Journal of Materials Engineering and Performance》2000,9(3):306-310
A steel containing 0.32 wt.% C, 0.88 wt.% Mn, 0.99 wt.% Si, 0.9 wt.% Ni, and 0.9 wt.% Cr was intercritically annealed at different
temperatures from 775 to 870 °C and quenched in oil to produce dual-phase steel microstructure. Tensile testing of these samples
gave a series of strengths and ductilities. The tensile strength increased with the increased annealing temperatures and the
martensite percentage increased with a reduction in ductility. Microvoids were formed near the fracture surfaces. The morphology
of the microvoids changed with the martensite percentage from decohesion of the martensite particles to the intergranular
and transgranular cracks, which defined the ultimate fracture mode of the specimens. The change in the morphology of microvoids
may be due to a high percentage of carbon in the steel, which produced stresses in the matrix (ferrite) during phase transformation. 相似文献
15.
采用拉伸试验、X射线衍射、光学显微镜和透射电镜等研究了一种13Cr超级马氏体不锈钢(00Cr13Ni6Mo2)的高温力学性能和高温时效后的力学性能、物相组成及显微组织。结果表明:00Cr13Ni6Mo2钢在高温下可保持较高的屈服强度,但当超过Af(奥氏体转变完成点)温度后,屈服强度迅速下降;600℃时效后,马氏体基体中的位错密度明显降低,同时产生了一定量的逆变奥氏体,导致时效100 h后其屈服强度从824 MPa降至682 MPa(下降17.2%),而抗拉强度和伸长率变化不大;800℃时效过程中,试验钢的组织完全奥氏体化,在降温过程中组织转变为淬火马氏体,故其具有典型的淬火马氏体性能特征,时效100 h后抗拉强度从858 MPa升至1031 MPa(提高20.2%),同时伸长率从22.5%降至15.0%。 相似文献
17.
18.
By means of surface mechanical attrition (SMA), a nanostructured surface layer was formed on a 0Cr18Ni9Ti austenite stainless steel plate. A strain-induced martensite transformation was observed during SMA treatment, and a single magnetic martensite phase layer with thickness of about 30 μm was gotten. The grain growth and phase transformations in the nanocrystalline layer are investigated during heating. The grain growth exponent for nanocrystalline polycrystalline steel is estimated. The kinetics mechanism governing the grain growth in the nanocrystalline layer is discussed. The martensite in the surface layer is quite stable and the temperature at which the reverse transformation of martensite to austenite starts during heating is about 500 ℃. 相似文献