Optimization of Heat Treatment process and Quenching cycles for Hadfield steel

Abstract

Hadfield steel is widely used in heavy-duty applications involving high impact loads and abrasive wear, such as mining and stone crushing equipment, due to its high toughness, ductility, and work-hardening ability. However, the as-cast microstructure contains carbide precipitation and chemical segregation, particularly along grain boundaries, which causes embrittlement and reduce service performance. Therefore, proper heat treatment followed by rapid quenching is essential to dissolve carbides and retain fully austenitic microstructure.

The aim of this thesis was to investigate and optimize heat treatment and quenching cycles for different Hadfield steel Grades, with focus on thermal gradients in thick sections, carbide dissolution, grain size, and hardness.

Two steel Grades were studied, GRADE A and GRADE B, using different sample geometries. Thick blocks were used to study thermal gradients between the core and surface, where plate samples were used to compare different heat treatment cycles.

The results showed significant differences between the surface and core temperature during the quenching, demonstrating the challenge of heat-treating thick Hadfield steel components due to the material’s poor thermal conductivity. Among the heat treatment cycles investigated, the temperature step-down method prior to quenching and the two-step heat treatment showed promising results of carbide-free microstructure while maintaining refined grain size.

Overall, this thesis highlights the importance of optimizing the heat treatment and quenching parameters according to section thickness and chemical composition.

Popular Abstract

Improving Heat Treatment of Tough Steel Components

Large steel components used in mining and rock-crushing equipment undergoes heavy impacts and
severe wear; therefore, the material used should withstand these conditions. Hadfield steel is well
suited for these applications, but the steel must be heat treated properly to obtain these properties.
High-manganese steel, also known as Hadfield steel, is commonly used in demanding applications
such as rock crushing because it is tough, ductile, and has the ability to become harder during service. However, these desirable properties depend on achieving a carbide-free microstructure.

In the as-cast condition, the material contains carbides that forms during solidification, these carbides make the steel brittle and reduce its performance. Therefore, the steel component must be heated to a high temperature to dissolve the carbides and then rapidly cooled in water to obtain the desired microstructure.

This process becomes more challenging for thick components. The surface of a large part heats and
cools faster than the core, creating temperature differences inside the component. If the cooling is too slow, carbides may form again, especially in the core region. Large temperature difference may also increase the risk of thermal cracking. This thesis investigated this challenge by monitoring heat treatment and quenching processes and by studying how different heat treatment and quenching
methods affect the microstructure and hardness of Hadfield steel.

Two Hadfield steel grades with different chemical compositions were studied to evaluate how
alloying elements influence the heat treatment. K-type thermocouples were placed at different depths
inside thick steel blocks to measure temperate changes inside the blocks during heating and
quenching. Samples were taking from different regions of the blocks to study microstructural
variations. Smaller plates were also treated using different heat treatment methods and examined
using optical microscopy, grain size measurements and Vickers hardness testing.

The results showed that the temperature difference between the surface and core was relatively small
during heating, but much larger during quenching. This indicates that quenching is the main limitation when heat treating thick Hadfield steel components. The core required twice as long to cool compared with the surface region, making it difficult to achieve a uniform microstructure throughout the part.

Among the tested methods, stepping down the temperature to 1000°C before quenching showed
promising results. This method reduced the amount of heat that had to be removed during quenching,
while still producing a carbide-free microstructure. The two-step heat treatment was also successful
in achieving its goals for one steel grade. However, the two grades behaved differently in some cycles due to difference in chemical composition.

Overall, the work helped in evaluating different heat treatment cycles and showed that the heat
treatment of Hadfield steel should be optimized according to both section thickness and chemical
composition. The results can help improve heat treatment effectiveness to support the production of
more reliable thick components for the demanding industrial applications.

• author: Alsebaie, Abdullah
• supervisor: Mats Andersson; Latifa Melk
• organization: Production and Materials Engineering
• course: MMTM05 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Hadfield Steel, heat treatment, quenching, thermocouple.
• other publication id: LUTMDN/(TMMV-5392)/1-93/2026
• language: English
• id: 9233259
• date added to LUP: 2026-06-11 15:00:21
• date last changed: 2026-06-11 15:00:21