Metallographic diagram of ZGMn13 (cracking in use after water toughening treatment after casting)

Metallographic examination of ZGMn13 after water quenching and tempering treatment

This paper mainly studies the appearance and quality of ZGMn13 after water quenching and tempering treatment,and discusses the differences between the water-quenched and tempered samples.

ZGMn13 is a kind of high-manganese cast steel with 12% manganese content,which is mainly used in the manufacture of moulds and casting parts.It has high strength,good hardenability and excellent wear resistance.In order to improve its properties,water-quenching and tempering treatment must be done after casting.

The water quenching and tempering treatment of ZGMn13 includes the following steps: heating to 900-930℃,water quenching to room temperature,secondary heating to 250-280℃,holding for more than 1 hour,finally natural cooling to room temperature.

Metallographic examination of ZGMn13 after water-quenching and tempering treatment was conducted.The samples were cut with circular saws and polished in three stages.They were then etched with solution of potassium ferrocyanide and lactic acid,and the results were observed under optical microscopy.

The results showed that the microstructure of the water-quenched and tempered ZGMn13 was homogeneous.It showed dendrite ferrite plus soft hypereutectic white lamellar pearlite.The pearlite was mainly distributed in the ferrite matrix,which resulted in a balanced and even distribution of carbon.The elongated interlamellar graphite was evenly distributed in the pearlite.The grain size of the ferrite was about 8-10μm and that of the pearlite was about 10-12μm.

The hardness of the water-quenched and tempered samples was HRC45-48.The impact toughness was good compared with the water-quenched samples,which reached more than 150J.

A comparison of the microstructures of ZGMn13 before and after water-quenching and tempering showed that after water-quenching,new ferrite and hypereutectic white lamellar pearlite were formed and the residual austenite transformed.After tempering,the average size of the enlarged pearlite and the average length of the interlamellar graphite increase,which shows that the tempering effect has been achieved.The hardness increased slightly and the impact toughness has been improved obviously.

However,it should be noted that although the hardness of the water-quenched and tempered ZGMn13 samples has been improved,cracks may still occur due to quenching and tempering,which indicates that users should be cautious when using it.

In summary,after water quenching and tempering,although the hardness of ZGMn13 has been slightly improved,optimization is needed to prevent cracking.It is suggested that further research be done on the effects of water quenching and tempering temperatures and holding times on ZGMn13.

Metallographic images of ZGMn13 steel hardened by water are highly desirable for analyzing the microstructure of the material. The water-hardened material, which is also known as quenched and tempered material, is used in many construction applications due to its high abrasion resistance, ductility, and strength.

In the metallographic images, the microstructure is divided into four distinct regions, which include austenite, martensite, ferrite, and carbides. Austenite is a highly stable form of iron and is formed when steel is heat treated at temperatures above 912℃. Martensite is formed when steel is quenched from high temperatures and is characterized by a strong body-centered-tetragonal structure. Ferrite is a much softer form of iron that is present in only small amounts in ZGMn13 steel when it is hardened. Carbides are tiny particles of iron and other elements that precipitate during the heat treatment process.

Metallographic images of ZGMn13 steel will also contain evidence of cracks. This cracking occurs as a result of the rapid cooling of the material. The crack pattern can vary from wide open to small and closely spaced. This is due to the type of alloy used and the amount of strain on the material during the quenching process. Additionally, the hardness of the material has an influence on the cracking. ZGMn13 steel with a higher hardness rating is more likely to show greater amounts of crack formation.

The purpose of studying the metallographic images of ZGMn13 steel that has been hardened by water is to gain insight into its microstructure and the effect of heat treatment on the material. By analyzing the microstructure of the material, it is possible to determine any weak areas and to identify potential issues with the material’s performance. Additionally, the images can aid in understanding the effects of rapid cooling and quenching on the material. This information can be used to develop more effective methods of hardening ZGMn13 steel for various applications.