CONTINUOUS-COOLING TRANSFORMATION CHARACTERISTICS AND HIGH-TEMPERATURE FLOW BEHAVIOR OF A MICROALLOYED SAE 1141 STEEL - Technical report - 1991

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NISTIR 3964 reports continuous-cooling transformation (CCT) characteristics and the high-temperature flow behavior of a microalloyed SAE 1141 steel. The study examines phase transformation kinetics during controlled reheating and cooling schedules, supported by metallography and hardness measurements. True stress–true strain curves are used to characterize deformation responses at elevated temperatures. The work also evaluates how recrystallization can be used to control austenite grain size, linking microstructure evolution to mechanical behavior.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages44

Reading Time1 h 51 min

AccessFree to download

I. INTRODUCTION

II. EXPERIMENTAL PROCEDURES

Continuous-Cooling Transformation (CCT) Characteristics

Metallography

Hardness Measurements

True Stress-vs.-True Strain Curves

Using Recrystallization to Control Austenite Grain Size

III. EXPERIMENTAL RESULTS AND DISCUSSION

IV. SUMMARIES AND CONCLUDING REMARKS

V. ACKNOWLEDGMENTS

VI. REFERENCES

√ NISTIR 3964 CONTINUOUS-COOLING TRANSFORMATION CHARACTERISTICSAND HIGH-TEMPERATURE FLOWBEHAVIOR OFA MICROALLOYEDSAE 1141 STEEL Yi-Wen ChengAvinoam Tomer NISTIR 3964 CONTINUOUS-COOLING TRANSFORMATION CHARACTERISTICSAND HIGH-TEMPERATURE FLOWBEHAVIOR OFA MICROALLOYEDSAE 1141 STEEL Yi-Wen ChengAvinoam Tomer* Materials Reliability Division Materials Science and Engineering LaboratoryNational Institute of Standards and TechnologyBoulder,Colorado 80303-3328 February 1991 *Guest researcher from Nuclear Research Center-Negev,Beer Sheva,Israel U.S.DEPARTMENT OF COMMERCE,Robert A.Mosbacher,SecretaryNATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY,John W.Lyons,Director CONTENTS Page ABSTRACT …………………………………………………………… ………………………………………………………………………………………vii I. INTRODUCTION …………………………………………………………………………………………………1 II. EXPERIMENTAL PROCEDURES ………………………………………………………………2 III. EXPERIMENTAL RESULTS AND DISCUSSION …………………………………3 Continuous-Cooling Transformation(CCT) Characteristics ………………………3 Metallography ………………………………………………………………………………………………………………………………5 Hardness Measurements ………………………………………………………………………………………………………8 True Stress-vs.-True Strain Curves……………………………………………………………………………8 Using Recrystallization to Control Austenite Grain Size ………………………………10 IV. SUMMARIES AND CONCLUDING REMARKS…………………………………11 V. ACKNOWLEDGMENTS ……………………………………………………………………………13 VI. REFERENCES ………………………………………………………………………………………………………14 LIST OF TABLES 1. Chemical composition of the microalloyed SAE 1141 steel(mass percent). 2 2. Experimental conditions…………………………………………………………………………………………………………3 3. Results of microhardness measurements. ……………………………………………………………………8 4. Values used to calculate Q and C in equation(4)…………………………………………………9 5. Computed austenite grain sizes after different deformation schedules…………11 LIST OF FIGURES 1. The CCT diagram of the microalloyed SAE 1141 steel after reheatedto 1218℃.F:ferrite;P:pearlite;B:bainite;M:martensite........ 16 2. The CCT diagram of the microalloyed SAE 1141 steel after reheatedto 1218℃ and compressed 50%at 900 ℃.F:ferrite;P:pearlite; B:bainite;M:martensite...................... . 17 3. The CCT diagram of the microalloyed SAE 1141 steel after reheatedto 1218℃ and compressed 50%at 1000℃.F:ferrite;P:pearlite; B:bainite;M:martensite........................ 18 4.The CCT diagram of the microalloyed SAE 1141 steel after reheatedto 1218℃ and compressed 50%at 1100℃.F:ferrite;P:pearlite; B:bainite;M:martensite.................................. 19 5.Strain distribution along AA'of a deformed specimen with a 50%height reduction.The original height of the specimen was 18 mm.There is small or no strains near the top(A)and bottom(A')surfaces.The strains are higher at locations close to themiddle(O).The strain is small near the point D.The strainis calculated using the grain height measurements explained infigure 6............................................... 20 6.The microstructural technique used to estimate the strain distributionafter a cylindrical specimen was compressed.The technique isapplicable only if the deformation is carried out at temperatureswhere no grain recrystallization takes place.................... 20 7. Picture of a production yoke.............................. 21 8. Microstructure of a yoke(MA SAE 1141 steel)produced with aproduction schedule................................ ··..... 21 9. Microstructure of a laboratory specimen(d0 condition)cooledat a comparable rate of a production yoke.The ASTM austenitegrain size number is 3.5................................... 22 10. Microstructure of a laboratory specimen(d0 condition) with a cooling time of 45.9s to cool from 800 to 500 ℃……………………………………………22 11. Microstructure of a laboratory specimen(d0 condition) with a cooling time of 24.8s to cool from 800 to 500 ℃……………………………………………23 12. Microstructure of a laboratory specime

FAQs

What material and processing route does the report focus on?

The report focuses on a microalloyed SAE 1141 steel subjected to continuous-cooling conditions following reheating and controlled cooling schedules.

How are transformation characteristics evaluated?

Transformation characteristics are evaluated using continuous-cooling transformation (CCT) characteristics supported by metallography and hardness measurements.

Which mechanical response is analyzed at high temperature?

High-temperature deformation response is analyzed using true stress–true strain curves measured at elevated temperatures and strain rates.

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