อิทธิพลของวัตถุดิบและพารามิเตอร์การหล่อต่อคุณสมบัติของเหล็กกล้าแมงกานีสสูง

Effect of Raw Materials and Casting Parameters on Properties of High Manganese Steel

Name: อมรศักดิ์ เร่งสมบูรณ์

Name: Amornsak Rengsomboon

Organization : มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี. คณะพลังงานสิ่งแวดล้อมและวัสดุ. สายวิชาเทคโนโลยีวัสดุ

keyword: โครงสร้างงานหล่อ

Abstract: High manganese steel is a special class of steels having austenite matrix after heat treatment due to high manganese content. Major properties of this steel are good toughness, low crack propagation rate and high work hardening rate. It is therefore widely used where wear resistance and high impact strength are required. It is normal practice in melting high manganese steel to used some scraps in charge materials. It is often found that the greater the amount of scraps, the worse the properties of castings. Wear resistance is reduced and the propensity to cracking increase without apparent reasons. The purpose of this research is to study the influence of scrap content of charge materials, section size, and pouring temperature on microstructure and properties of high manganese steel. Macroscopic study of cylindrical workpieces revealed 3 zones of the structures : chill zone, columnar zone and equiaxed zone. The grain size and carbide quantity in chill zone are almost the same for all the casting being 30 microns and 1.3%, respectively. In columnar zone the grains were found to be approximately of the same width but varying in length depend on the amount of scrap used the amount of carbide were found to be about 2.7-4.2% by area. Dendrite arms spacing were about 80microns over the columnar zone. In equiaxed zone the grain sizes were found to be dependent on the amount of scraps used. However, carbide quantity and dendrite arms spacing were the same for each specimen. The amount of impurities was found to be increased with increased scrap content. Two kinds of impurities were observed :manganese sulfide and manganese silicate. ?Increasing scrap content from 0% to 100% leads to lowering the strength by 22% and elongation by 38% as compared to that with no scrap. The hardness values were slightly decreased when higher amount of scrap was used. Section size also affects microstructure. The grain size of 50 mm. casting was greater than those in 25 mm. but the amount of carbide, impurities and dendrite arm spacing were found to be approximately equal. The hardness of 25 mm. casting was greater than that of 50 rnm. one but the elongation was lower. At pouring temperature of 1,510 O C ,large and long columnar grains were obtained at the surface and larger equiaxed grains at the center compared with those in the casting poured at 1,470 O C. Besides, the size of carbide and length of dendrite arm were also greater in the castings poured at higher temperature. Tensile strength and hardness of the casting poured at 1,470 ? C were higher but the elongation was less compared with those poured at 1,5 10 ? C.

มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี. สำนักหอสมุด

Address: กรุงเทพมหานคร

Email: info.lib@mail.kmutt.ac.th

Name: ปัญญา ศรีจันทร์

Role: อาจารย์ที่ปรึกษา

Created: 2544

Issued: 2007-01-19

Modified: 2007-03-12

วิทยานิพนธ์/Thesis

ISBN: 9749551188

CallNumber: MT161

tha

DegreeName: วิศวกรรมศาสตรมหาบัณฑิต

Level: ปริญญาโท

Descipline: เทคโนโลยีวัสดุ

Grantor: มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

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3	MT161ab.txt	3.09 KB	8	2018-05-10 17:04:09

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