Preheating Temperature Effect on Crystal Structure and Texture of Martensitic Stainless Steel

Abstract

Theoretically, the preheating temperature refers to the start martensite temperature (Ms), and the martensite transformation can be considered as the conservation of the invariant habit-plane in the lattice structure. The habit-plane is the interface plane between austenite and martensite as measured on a macroscopic scale. From the calculation, Ms = 252 °C. The martensite formation can be affected by temperature or stress treatment. In this experiment, temperature treatment was conducted. The sample was treated at 250 °C ± 10 °C. Before and after the pre-heat treatment, the sample was characterized using the neutron diffraction method. BATAN's Texture Diffractometer (DN2) with a neutron wavelength of 1.2799Å was used to characterize the sample. Analysis of the crystal structure showed that there are three phases before the preheating. The lattice parameters (a) obtained were as follows: for the -phase, a = 2.8501 ± 0.0004 Å; for the α'phase, a= b =2.517 ± 0.003 Å, and c= 3.581 ± 0.002 Å; for the -phase, a= 3.5884 ± 0.0004 Å, Rwp = 17.94%, and  = 1.33. After preheating, only the -phase appears with a = 3.5830 ± 0.0005 Å, Rwp = 26.03%, and  = 1.17. The orientation distribution function is modeled by the sample symmetrization model based on triclinic to orthorhombic sample symmetry. It shows that, before being preheated, the -phase has {100} <001> with texture index (F 2 ) between 0.701 m.r.d. to 3.650 m.r.d., the α-phase has a texture index between 0.923 m.r.d. to 1.768 m.r.d., and the '-phase has a texture index between 0.910 m.r.d. to 1.949 m.r.d. After being preheated, the -phase also has {100} <001> with a texture index between 0.846 m.r.d. to 3.706 m.r.d. It can be concluded, that because of the high preheating temperature, a phase change from martensite to austenite occurred that allowed the sample to be welded easily. After preheating, the -phase has the same cubic type orientation {100} <001>, and the texture index is nearly the same as that before preheating, with not martensite present. AbstrakPengaruh Suhu Pemanasan-Awal pada Struktur Kristal dan Tekstur Baja Tahan Karat Martensitik. Secara teoritis, suhu pemanasan awal mengacu pada suhu martensit awal (Ms), dan transformasi martensit dapat dianggap sebagai konservasi dari habit-plane invarian dalam struktur kisi. Habit-plane adalah bidang antarmuka antara austenit dan martensit yang diukur pada skala makroskopik. Dari perhitungan, Ms = 252 °C. Pembentukan martensit dapat dipengaruhi oleh suhu atau perlakuan tekanan. Dalam percobaan ini, perlakuan suhu dilakukan. Sampel diperlakukan pada 250 °C ± 10 °C. Sebelum dan sesudah perlakuan pemanasan-awal, sampel dikarakterisasi menggunakan metode difraksi neutron. Difraktometer Tekstur BATAN (DN2) dengan panjang gelombang neutron 1,2799 Å digunakan untuk mengkarakterisasi sampel. Analisis struktur kristal menunjukkan bahwa ada tiga fase sebelum pemanasan awal. Parameter kisi (a) yang diperoleh adalah sebagai berikut: untuk fasa-α, a = 2,8501 ± 0,0004 Å; untuk fasa-α', a = b = 2,517 ± 0,003 Å, dan c = ...

Development of Automatic Data Processing for Batan’s HRPD and FCD/Td Using Python Code

“…FCD/TD, on the other hand, can obtain texture data to analyze the crystalline orientation. A recent example is the texture of Stainless Steel SS420 [3]. This is possible due to the four-circle configuration that refer to four rotation axis consisting of two instrument rotation axis, which are 2-theta (2 ) and theta ( ) or omega ( ), and 2 sample angular rotation axis which are pi ( ) and chi ( ).…”