ZCOOCr18Ni10 (solution treatment at 1100°C after casting) low magnification structure

Effects of Aging Treatments on THE Microstructure and Mechanical Properties of 18Ni-10Co-0.2C Cast Steel

Introduction

Cast steel is a metal material that consists of iron, carbon, and small amounts of other elements. As a common steel, it is widely used in modern engineering and the mechanical industry making components. 18Ni-10Co-0.2C cast steel alloys possess good oxidation resistance and high strength and hardness, making them a popular choice for use in engine parts and other components requiring high durability. However, cast steel components are often subject to low temperature aging treatments after forming, to improve mechanical properties.

In this study, the effects of aging treatments on the microstructure and mechanical properties of 18Ni-10Co-0.2C cast steel alloy were investigated. Four types of aging treatments were performed on cast steel specimens: a solution treatment at 1100°C, and three various aging treatments at 500°C, 600°C and 650°C, respectively.

Experimental Procedure

The 18Ni-10Co-0.2C cast steel specimens were solution treated in an electric furnace at 1100°C and then water quenched to obtain a homogeneous ferrite-pearlite morphology. The four types of specimens were then given aging treatments at 500°C, 600°C, 650°C and 1100°C, respectively.

The mechanical properties and microstructure of the specimens were evaluated using a metallographic microscope, X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The microstructure of the specimens was observed using the SEM, and their phase composition and lattice parameters were obtained using an XRD.

Results

The results of the SEM analysis and XRD analysis showed that aging treatments at 500°C, 600°C, and 650°C did not significantly change the structure of the 18Ni-10Co-0.2C cast steel alloy, while the solution treatment at 1100°C resulted in a homogeneous ferrite-pearlite morphology.

The hardness of the cast steel alloy after aging treatments was measured and is shown in Figure. It can be seen that the hardness of the specimens increased with an increase in aging temperature. The hardness of the material after aging treatment at 1100°C was highest, followed by those of the specimens aged at 600°C, 650°C and 500°C, respectively.

Discussion

The results of the mechanical properties and microstructure analysis showed that aging treatments of 18Ni-10Co-0.2C cast steel alloy at 500°C, 600°C, and 650°C did not significantly change the structure of the alloy, while the solution treatment at 1100°C resulted in a homogeneous ferrite-pearlite morphology. The hardness of the material was highest after the solution treatment at 1100°C and decreased with decreasing aging temperature.

The results of the present study demonstrate that the 18Ni-10Co-0.2C cast steel alloy after aging treatment at 1100℃ in the solutionizing process exhibited the best mechanical properties, with a microstructure of homogenized ferrite-pearlite morphology.

Conclusion

The effects of aging treatments on the microstructure and mechanical properties of 18Ni-10Co-0.2C cast steel were investigated. The results showed that the hardness of the material increased with an increasing aging temperature, with the highest hardness achieved after a solution treatment at 1100°C. The material had a microstructure of homogenized ferrite-pearlite morphology after solution treatment.

The present study provides an understanding of the effects of aging treatments on the microstructure and mechanical properties of 18Ni-10Co-0.2C cast steel alloy. This information will be useful for the design and optimization of components made of this material.

Solution heat treatment of ZCOOCr18Ni10 (cast hardened 1100°C) Low Magnification Microstructure

Solution heat treatment is a common method for heat treatment of ZCOOCr18Ni10 (cast hardening 1100°C). The most common alloy is an austenitic stainless steel material. If a part of this material is subjected to solution heat treatment, the objective is to dissolve from the solid solution all precipitates which are formed by a secondary heat treatment. This is done to increase the ductility and toughdness of the material.

The microstructure of ZCOOCr18Ni10 under the low magnification after solution heat treatment is mainly composed of austenite, which has a ferritic-austenitic structure with small grains of ferrite and austenite in a granulated matrix. The particles of ferrite that exist in the matrix have a square or angular shape. However, there is also some regional precipitation of secondary phases in the matrix, such as carbonates and carbides.

The microstructure of ZCOOCr18Ni10 under the low magnification after solution heat treatment shows almost no change, although there may be some localized precipitation of second phases in the matrix. The microstructure of ZCOOCr18Ni10 after solution heat treatment is mainly composed of austenite and ferrite, which form a ferritic-austenitic grain structure with small grains of austenite and ferrite in a granulated matrix. The grains of ferrite in the matrix have a square or angular shape.

In summary, solution heat treatment of ZCOOCr18Ni10 (cast hardening 1100°C) has a low magnification microstructure which is mainly composed of austenite and ferrite grains in a granular matrix. There is some localized precipitation of second phases in the matrix, but the overall structure is mostly unchanged. Solution heat treatment is therefore an effective way to improve the materials ductility and toughness.