scholarly journals Effect of Processing Parameters on Interphase Precipitation and Mechanical Properties in Novel CrVNb Microalloyed Steel

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 107
Author(s):  
Andrii Kostryzhev ◽  
Chris Killmore ◽  
Elena Pereloma

Novel steel microalloyed with 0.73 (Cr + V + Nb) has been subjected to thermomechanical processing (TMP) with varying parameters to simultaneously maximise the steel strength and ductility. Optical and electron microscopy studies coupled with uniaxial tensile testing were carried out to analyse the processing-microstructure-properties relationship. For the suggested steel composition, the simultaneously highest yield stress (960 MPa), ultimate tensile strength (1100 MPa), and elongation to failure (25%) were achieved following simulated coiling at 650 °C and holding for 30 min. The variation in the finish rolling temperature affects the ferrite grain size and the ratio of precipitates formed in austenite and ferrite. If a significant amount of solute is consumed for precipitation in austenite and during subsequent growth of strain-induced precipitates, then a lower fraction of interphase and random precipitates forms in ferrite resulting in a lower strength. Extended time at a simulated coiling temperature resulted in the growth of interphase precipitates and precipitation of random ones in ferrite. Fine tuning of TMP parameters is required to maximise the contribution to strength arising from different microstructural features.

Author(s):  
A. S. Atamashkin ◽  
E. Yu. Priymak ◽  
N. V. Firsova

The paper presents an analysis of the mechanical behavior of friction samples of welded joints from steels 30G2 (36 Mn 5) and 40 KhN (40Ni Cr 6), made by rotary friction welding (RFW). The influence of various temperature conditions of postweld tempering on the mechanical properties and deformation behavior during uniaxial tensile testing is analyzed. Vulnerabilities where crack nucleation and propagation occurred in specimens with a welded joint were identified. It was found that with this combination of steels, postweld tempering of the welded joint contributes to a decrease in the integral strength characteristics under conditions of static tension along with a significant decrease in the relative longitudinal deformation of the tested samples.


Author(s):  
C. San Marchi ◽  
L. A. Hughes ◽  
B. P. Somerday ◽  
X. Tang

Austenitic stainless steels have been extensively tested in hydrogen environments. These studies have identified the relative effects of numerous materials and environmental variables on hydrogen-assisted fracture. While there is concern that welds are more sensitive to environmental effects than the non-welded base material, in general, there have been relatively few studies of the effects of gaseous hydrogen on the fracture and fatigue resistance of welded microstructures. The majority of published studies have considered welds with geometries significantly different from the welds produced in assembling pressure manifolds. In this study, conventional, uniaxial tensile testing was used to characterize tubing of type 316L austenitic stainless steel with an outside diameter of 6.35 mm. Additionally, orbital tube welds were produced and tested to compare to the non-welded tubing. The effects of internal hydrogen were studied after saturating the tubes and orbital welds with hydrogen by exposure to high-pressure gaseous hydrogen at elevated temperature. The effects of hydrogen on the ductility of the tubing and the orbital tube welds were found to be similar to the effects observed in previous studies of type 316L austenitic stainless steels.


2002 ◽  
Vol 62 (1) ◽  
pp. 73-81 ◽  
Author(s):  
J. M. García Páez ◽  
A. Carrera ◽  
E. Jorge Herrero ◽  
I. Millán ◽  
A. Rocha ◽  
...  

2001 ◽  
Author(s):  
M. A. Haque ◽  
M. T. A. Saif

Abstract We present a MEMS-based technique for in-situ uniaxial tensile testing of freestanding thin films inside SEM and TEM. It integrates a freestanding thin film specimen with MEMS force sensors and structures to produce an on-chip tensile testing facility. Cofabrication of the specimen with force and displacement measuring mechanisms produces the following unique features: 1) Quantitative experimentation can be carried out in both SEM and TEM, 2) No extra gripping mechanism is required, 3) Specimen misalignment can be eliminated, 4) Pre-stress in specimen can be determined, and 5) Specimens with micrometer to nanometer thickness can be tested. We demonstrate the technique by testing a 200-nanometer thick Aluminum specimen in-situ in SEM. Significant strengthening and anelasticity were observed at this size scale.


Author(s):  
Dongil Kwon ◽  
Jong Hyoung Kim ◽  
Ohmin Kwon ◽  
Woojoo Kim ◽  
Sungki Choi ◽  
...  

The instrumented indentation technique (IIT) is a novel method for evaluating mechanical properties such as tensile properties, toughness and residual stress by analyzing the indentation load-depth curve measured during indentation. It can be applied directly on small-scale and localized sections in industrial structures and structural components since specimen preparation is very easy and the experimental procedure is nondestructive. We introduce the principles for measuring mechanical properties with IIT: tensile properties by using a representative stress and strain approach, residual stress by analyzing the stress-free and stressed-state indentation curves, and fracture toughness of metals based on a ductile or brittle model according to the fracture behavior of the material. The experimental results from IIT were verified by comparing results from conventional methods such as uniaxial tensile testing for tensile properties, mechanical saw-cutting and hole-drilling methods for residual stress, and CTOD test for fracture toughness.


2012 ◽  
Vol 271-272 ◽  
pp. 17-20
Author(s):  
Shu Yan Wu ◽  
Ze Sheng Ji ◽  
Chun Ying Tian ◽  
Ming Zhong Wu

This work is to study the influence of heat treatment on microstrudture and mechanical properties of AZ31B magnesium alloy prepared by solid -state recycling. AZ31B magnesium alloy chips were recycled by hot extruding. Three different heat treatments were conducted for recycled alloy. Mechanical properties and microstructure of the recycled specimen and heat treated specimen were investigated. 300°C×2h annealing specimen exhibits finer grain due to static recrystallization, and microstructure of 400°C×2h annealing specimen becomes more coarse. 300°C×2h annealing treatment improves obviously strength and ductility of recycled alloy. Ultimate tensile strength of alloy decreases and elongation to failure increases after 400°C×2h annealing. Grain size, dislocation density and bonding of chips have an effect on the elongation of recycled materials. 190°C×8h ageing has no influence on microstructure and mechanical properties of recycled alloy.


2000 ◽  
Author(s):  
T. Jesse Lim ◽  
Wei-Yang Lu

Abstract In this work, uniaxial tensile testing of a 63Sn-37Pb alloy with different specimen sizes and aging conditions had been carried out. Although the stress-strain responses of different specimen sizes and aging conditions differs, the ultimate strength of the specimens with 16 hours, 100°C aging are similar for the sizes tested. The specimens with 25 days, 100°C aging have different stress-strain response with different sizes, and have a lower ultimate strength and higher failure strain compared to 16 hours, 100°C aging specimens.


2021 ◽  
Vol 7 ◽  
Author(s):  
Alexandra Glover ◽  
John G. Speer ◽  
Emmanuel De Moor

The addition of a tempering or austempering step to the double soaking of a 0.14C–7.17Mn (wt pct) steel was investigated in the present contribution. The double soaking heat treatment is a two-step intercritical annealing heat treatment, which generates microstructures of athermal martensite, retained austenite and ferrite when applied to medium manganese steels. Microstructures following double soaking and (aus)tempering contained a combination of retained austenite, athermal or tempered martensite, and blocky or bainitic ferrite. X-ray diffraction, dilatometry and transmission Kikuchi diffraction were utilized to investigate microstructural changes which occurred during tempering or austempering. The resulting mechanical properties were measured using uniaxial tensile testing. The double soaking plus tempering heat treatment was shown to generate an ultimate tensile strength of 1,340 MPa in combination with 28 pct total elongation while the double soaking plus austempering heat treatment resulted in an ultimate tensile strength of 1,675 MPa and total elongation of 22 pct. Overall, both novel heat treatments produced a combination of strength and ductility desired for the third generation of advanced high strength steels.


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