{'fraction_non_alphanumeric': 0.03476245654692932, 'fraction_numerical': 0.038238702201622246, 'mean_word_length': 5.215827338129497, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Influence of Tempering Temperature on the Microstructure and Mechanical Properties of a Cr–Ni–Mo‐Alloyed Steel for Rock Drill Applications

This research investigates the mechanical properties of a Cr–Ni–Mo‐alloyed rock drill steel tempered at different temperatures from 150 to 550 °C. The highest strength, hardness, and impact energy occur when the steel is tempered at 180 °C. Strength, hardness, and impact energy decrease with increasing tempering temperature from 180 to 400 °C. For tempering temperatures higher than 400 °C, the steel exhibits: 1) an increase in impact energy; 2) an increase in strength and hardness when tempered at 420, 450, and 480 °C; and 3) a gradual decrease in strength and hardness when tempered at temperature higher than 480 °C. The mechanism of the changes of impact energy and hardness with tempering temperature is proposed.