Product yield for ECAE processing

Halle

et al. 2010

MSF

Abstract. In the present work, the near-threshold fatigue crack propagation (FCP) at different load ratios is studied for an aluminium alloy processed by equal-channel angular pressing (ECAP). The conditions under investigation represent different stages of microstructural refinement as well as a ductility-optimized condition with superior crack growth properties, obtained by a combination of ECAP and aging. The results show a strong dependency of the threshold and its load ratio sensitivity on the grain size and grain size distribution. These observations can be rationalized on the basis of crack path tortuosity and the contribution of (roughness-induced) crack closure. Moreover, the experimental data is evaluated using the two-parametric concept of Vasudevan and Sadananda, which employs two necessary minimum conditions for crack growth, namely a critical cyclic ∆K * th , and a critical maximum stress intensity K * max . The application of this concept shows a strong interaction of both parameters for all ECAP-processed conditions, where the ductility-optimized condition reveals superior FCP properties compared to the "as-processed" conditions.

Section: Methodsmentioning

confidence: 99%

Near-Threshold Fatigue Crack Propagation in an ECAP-Processed Ultrafine-Grained Aluminium Alloy

Halle

et al. 2010

MSF

“…The friction conditions inside the tooling are optimized by two movable walls in the inlet channel and a moving bottom slider in the outlet channel [18]. The ECA-extrusions were performed at 25 mm·min -1 , following route E [19]. To ensure homogeneous deformation and to prevent from cracking, controlled BPs up to 300 MPa were applied via the moving bottom slider.…”

Section: Figmentioning

confidence: 99%

Combining Equal-Channel Angular Extrusion (ECAE) and Heat Treatment for Achieving High Strength and Moderate Ductility in an Al-Cu Alloy

Meyer

Krüger

2008

MSF

Abstract. The effect of equal-channel angular extrusion (ECAE) on mechanical properties of an AA2017 produced by powder metallurgy is investigated. Special attention is given to the influence of heat treatment, processing temperature and backpressure on the workability for achieving high strength and moderate ductility. This is of special interest, since it is often reported that Al-Cu alloys have low ductility and therefore are prone to cracking during severe plastic deformation. It is shown that ECAE at high temperatures (>220°C) does not necessitate backpressure to ensure homogeneous deformation but leads to a significant sacrifice in strength due to in-situ precipitation. Thus, most of the extrusions are done at considerably low temperatures. Performing room temperature-extrusion is most effective in achieving high strengths but also requires high backpressures. Due to severe strain hardening during processing, the strength increase is combined with a reduction in ductility. Recently it was reported that a post-ECAE aging of pre-ECAE solution treated material is effective in enhancing the ductility of aluminium alloys. This approach was successfully transferred to the current alloy. A high-temperature, short-time aging after only one extrusion, for example, doubles the failure strain to a value of ~13%. Compared to the naturally aged condition with coarse grains that serves as reference (T4), an increase of 15 % in yield stress (YS) was obtained while retaining the ultimate tensile stress (UTS). Another effective approach is the combination of a pre-ECAE solution treatment with subsequent under-aging prior to ECAE. It is shown that performing ECAE at medium temperatures (160-180°C) enables a better workability and additionally gives higher strengths and better ductility compared to the processing in the water quenched condition. A remarkable YS of 530 MPa and an UTS of 580 MPa combined with a moderate failure strain of 11.6 % were achieved.

AIP Conference Proceedings

“…The ECAE plate was obtained by extruding AZ31B-H24 through a die using a hybrid 4E route [10]. The nominal grain size resulting from the ECAE process was approximately 3 μm.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

Microstructural effects on the spall properties of ECAE and SWAP magnesium alloys: AZ31B-4E and AMX602

Williams¹,

Farbaniec²,

Kecskes³

et al. 2017

Abstract. The effects of microstructure on the spall properties of two magnesium alloys fabricated via Equal-Channel Angular Extrusion (ECAE) and Spinning Water Atomization Process (SWAP) were investigated. The Hugoniot Elastic Limit (HEL) for both AZ31B-4E and AMX602 magnesium alloys were found to be approximately 0.181±0.003 GPa and 0.187±0.012 GPa, respectively. The spall strengths extracted from the free surface velocity profiles were found to decrease by approximately 4% for AZ31B-4E between 1.7 GPa to 4.6 GPa shock stress. Although this reduction in spall strength may lie within the experimental error, the microstructure of the post-shocked magnesium alloy show that manganese intermetallic inclusions in the AZ31B-4E magnesium were perhaps responsible for the reduction in spall strength as a function of shock stress. On the contrary, the spall strength for AMX602 was found to be random for the same shock stress range studied. This random behavior of the AMX602 was likely due to the incomplete sintering during mechanical processing. The fracture surfaces of both materials were dominated by nanovoids and the AMX602 fracture surface was found to be striated. A more in-depth study is needed to better understand the spall behavior of both materials.