Optimization of Sigma Phase Precipitates with Respect to the Functional Properties of Duplex Cast Steel

The dry sliding wear behavior of heat-treated super duplex stainless steel AISI 2507 was examined by taking pin-on-disc type of wear-test rig. Independent parameters, namely applied load, sliding distance, and sliding speed, influence mainly the wear rate of super duplex stainless steel. The said material was heat treated to a temperature of 850°C for 1 hour followed by water quenching. The heat treatment was carried out to precipitate the secondary sigma phase formation. Experiments were conducted to study the influence of independent parameters set at three factor levels using the L 27 orthogonal array of the Taguchi experimental design on the wear rate. Statistical significance of both individual and combined factor effects was determined for specific wear rate. Surface plots were drawn to explain the behavior of independent variables on the measured wear rate. Statistically, the models were validated using the analysis of variance test. Multiple non-linear regression equations were derived for wear rate expressed as non-linear functions of independent variables. Further, the prediction accuracy of the developed regression equation was tested with the actual experiments. The independent parameters responsible for the desired minimum wear rate were determined by using the desirability function approach. The worn-out surface characteristics obtained for the minimum wear rate was examined using the scanning electron microscope. The desired smooth surface was obtained for the determined optimal condition by desirability function approach.

Section: Introductionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 96%

Dry Sliding Wear Behavior of Super Duplex Stainless Steel AISI 2507: a Statistical Approach

Davanageri

Narendranath

Kadoli

2016

“…Cracks in the high-carbon low-alloyed hypereutectic cast steels used e.g. for production of tools for metallurgy industry are most frequently revealed only during the final mechanical working of the heat-treated castings [3][4][5][6]. The material for examination comes from the cracked steel mill rolls of several tons weight, made of either L180HMF or L200HNM cast steel.…”

Section: Results Of Investigation and Their Discussionmentioning

confidence: 99%

Fracture Mechanisms in Steel Castings

Stradomski¹,

Stachura²,

Stradomski³

2013

The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.

“…The heat treatment consisted of the solution heat treatment carried out at 1120°C for 2 hours and subsequent annealing at the temperature of 800°C and at times ranging from 30 to 180 minutes. The scope of examination included examinationof microstructure, quantitative metallographic analysis and inspection of erosive and corrosive wear.Metallographic examination were carried out for specimens etched with Mi21Fe reagent (30 g of potassium ferrocyanide, 30 g of potassium hydroxide, and 60 ml of distilled water) by means of Neophot 32 optical microscope and SEM JOEL JSM 6610LV scanning electron microscope.The shape factor R of each σ phase precipitate were determined by means of ImageProPlus program, as shown in work [5].…”

Section: Materials and Methods Of Examinationmentioning

confidence: 99%

Kinetics of the σ Phase Precipitation in Respect of Erosion-corrosion Wear of Duplex Cast Steel

Brodziak-Hyska

Stradomski

Kolan

2014

Self Cite

The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3- 3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated up to 70°C and containing Cl' and SO4 ions and solid particles produce high erosive and corrosive wear.The work proposes an application of the σ phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material. The paper presents the results of examination of the kinetics of σ phase precipitation at a temperature of 800°C and at times ranging from 30 to 180 minutes. Changes in the morphology of precipitates of the σ phase were determined using the value of shape factor R. Resistance to erosion-corrosion wear of duplex cast steel was correlated with the kinetics of sigma phase precipitating.