PSI - Issue 13

Shuai Wang et al. / Procedia Structural Integrity 13 (2018) 1940–1946 Author name / StructuralIntegrity Procedia 00 (2018) 000 – 000

1941

2

As a widely used metal material, austenitic stainless steel has a significant hardening after cold working [4-7]. In the 1960s, Armijo has studied the cold work hardening of 304 austenitic stainless steels at different temperatures. With the advancement of technology, great progress has been made in the study of the cold working of stainless steel[8]. The work hardening of types 316L and 316LN austenitic stainless steels was analysed by Soussan et al, the results show that the monotonic work hardening of 316L and 316LN austenitic stainless steels can be modelled by the modified Ludwik model proposed by Ludwigson [9]. Effect of plastic deformation induced by cold rolling or surface machining on the susceptibility to chloride-induced stress corrosion cracking at ambient temperature of 304L austenitic stainless steel was investigated, the results show that crack propagation in cold worked sample was along the slip lines and cracking occurred much earlier than in the solution annealed sample [10]. The microstructures, true stress-true strain curves and micro-hardness of two stainless steels, containing 1.0%N and 316L, after compressive deformation were measured. It was found that the mechanical twinning and sliping participated together in the deformation for the two steels under the deformation less than 20%, but sliping turned to be dominant for 316L when the deformation was increased to 50%, the high nitrogen steel still remained the above two mechanisms [11 12]. Tensile tests of cold rolled and annealed AISI301L and AISI304 stainless steel sheet samples with 2 mm in thickness were performed at different strain rates. The results show that the amount of strain induced α '-martensite in AISI301L is much higher than that in AISI304 when both steels are deformed at the same strain rate [13-14]. At present, the research on the cold work hardening of austenitic stainless steels mainly focuses on the effect of cold working deformation on the microstructure transformation and the mechanical properties of the materials. There are relatively few researches on the specific performance parameters of the materials under different cold working amounts. To obtain the preliminary data of the mechanical parameters with different cold deformation, the relation of the cold deformation and mechanical parameters of 316L austenitic stainless steel is analyzed by combining the theoretical analysis, numerical simulation and uniaxial tensile testing in this paper.

2. Experimental Process 2.1. Experimental materials and methods

The experimental adopts 316L austenitic stainless steel sheet provided by Shanxi Taigang Stainless Steel Co., Ltd. In accordance with the standard of GB/T24511-2009, the sheet surface dressing of plate shall be kept to a minimum. The plate tensile specimen thickness is 2mm, geometrical shapes as show in Fig.1. The chemical composition of 316L stainless steel as shown in Table 1.

Table 1. Chemical composition of 316L stainless steel (%).

C

Si

Mn

P

S

Cr

Ni

Mo

0.03

0.75

2.00

0.03

0.02

16.07

12.01

2.12

Fig.1. Plate tensile specimen

2.2. Uniaxial tensile test of 316L stainless steel tensile specimens To ensure the data reliability of the uniaxial tensile experiment, the same batch of 4 plate tensile specimens were used using PLD-50KN type microcomputer tensile test machine to stretch the specimens respectively 2mm, 4mm, 6mm, 8mm (predeformation amount 10%, 20%, 30%, 40%). Samples with different amounts of cold work are obtained, and the pre-fabricated samples are re-stretched until the samples are broken to compare the mechanical properties of the materials after cold work hardening. Tensile process of plate specimen as shown in Fig.2.