{'fraction_non_alphanumeric': 0.016597510373443983, 'fraction_numerical': 0.021784232365145227, 'mean_word_length': 5.892857142857143, '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}}
Effect of Heat Treatment on Microstructural Evolution of 13Cr Martensitic Stainless Steel

13Cr martensitic stainless steels are widely used in gas industry, which are usually manufactured by quenching-tempering treatment. Microstructural study of 13Cr steel through various heat treatments was carried out for determining the optimum parameters for industry manufacture. After quenching treatment at 975 °C for 20 min, precipitation-free martensitic structures were formed. During tempering, recovery of martensite through grain boundaries migration and dislocations annihilation was found to soften the steel. In addition, transformation of needle-like Cr7C3 carbides to the irregular shaped Cr23C6 carbides was observed when tempering temperature is above 710 °C. The phase transformation induced precipitation strengthening is discussed. The optimum heat treatment parameters of 13Cr steel for avoiding over tempering and the precipitation hardening are found.